EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: Electro Fan on February 05, 2015, 03:39:49 am
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Here is an example of an eBay spectrum analyzer for under $1k.
http://www.ebay.com/itm/Tektronix-496P-Programmable-Spectrum-Analyzer-1-8GHz-/361202642579?pt=LH_DefaultDomain_0&hash=item54195aee93 (http://www.ebay.com/itm/Tektronix-496P-Programmable-Spectrum-Analyzer-1-8GHz-/361202642579?pt=LH_DefaultDomain_0&hash=item54195aee93)
There are the Tektronix 490 and 2700 series, and the HP 8500 and 3500 series, and probably others. The only spec I have nailed down so far is more bandwidth (from as low as possible to as high as possible) is good :). Realistically up to 1.8 GHz will do and whatever the low end can be within the budget will suffice.
Anyone have any recommendations on the best value model for a used spectrum analyzer assuming the unit is in good operating condition? Anything you've found to be a favorite? How feasible is it to get a decent used spectrum analyzer along with a tracking generator for under $1k?
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Here is an example of an eBay spectrum analyzer for under $1k.
http://www.ebay.com/itm/Tektronix-496P-Programmable-Spectrum-Analyzer-1-8GHz-/361202642579?pt=LH_DefaultDomain_0&hash=item54195aee93 (http://www.ebay.com/itm/Tektronix-496P-Programmable-Spectrum-Analyzer-1-8GHz-/361202642579?pt=LH_DefaultDomain_0&hash=item54195aee93)
There are the Tektronix 490 and 2700 series, and the HP 8500 and 3500 series, and probably others.
These were very good SAs in their days but now they are pretty much antiques which usually require a lot of care and which come with lots of unobtainium parts.
Unless you really need the bandwidth on a shoestring budget I wouldn't invest in such an dinosaur.
The only spec I have nailed down so far is more bandwidth (from as low as possible to as high as possible) is good :). Realistically up to 1.8 GHz will do and whatever the low end can be within the budget will suffice.
Anyone have any recommendations on the best value model for a used spectrum analyzer assuming the unit is in good operating condition? Anything you've found to be a favorite? How feasible is it to get a decent used spectrum analyzer along with a tracking generator for under $1k?
Well, you said tracking generator so you want an old-style swept SA which are still somewhat expensive. However, if you can do without a tracking generator then there are quite a few options in the form of Vector SAs (VSA).
For example, have a loot at the Agilent E7495A/B. These are portable Base Station Test Sets which means you not only get a SA (500kHz to 2.7GHz, span from zero to full bandwidth) but also an RF generator (200MHz to 2.7GHz), a power meter, and (which is why many people want a tracking gen in the first place) a cable tester and TDR fault locator. It also has a GPS clock source. All in a sturdy ruggedized box that can take two rechargeable batteries and doesn't take much space on the bench (size-wise like a modern mid-range scope). They are a great bargain if you can find one with the right options below $1k (which with some patience is possible).
If I find the time I'll do a review of my E7495B over the weekend.
There are other alternatives, i.e. Anritsu MT8802A and Rohde & Schwarz CMU200. I have the latter, and it's a great device (mine has two RF gens, the audio analyzer, and the Reference OXCO).
There's also the Agilent E4406A which is a vector SA which goes to 4GHz but it only offers 10MHz span which is pretty poor. And it's essentially a SA only so it doesn't have any RF generator or other functionality.
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There's also the Agilent E4406A which is a vector SA which goes to 4GHz but it only offers 10MHz span which is pretty poor. And it's essentially a SA only so it doesn't have any RF generator or other functionality.
Seems to be normal for a vector SA, since for VSAs it probably goes like that: Input*LO => IF => some filtering => ADC => FFT. So 20MS/s sample rate ADC to get 10MHz span. Any higher sample rate, and the dynamic range goes down and price goes up significantly.
If you have the space, then buy a 8566/8568. Best SA for the price (less than 500$ w/o shipping if you can wait and pick it locally). The Tek 7L14 I had before my HP 8568B were crap (everything cramped inside that 3 plugin wide box, therefore everything is very small, difficult to disassemble and probe, no nice CF readout, drifty YIG, because not phase locked in higher span ranges). Since the 494P is related to the 7L14, I personally wouldn't buy it.
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I would look for either the HP 8560E series or the 8590E series. I have several pieces of HP gear going back to the early 80's that is run daily and has never been repaired or needed it. They're like the Timex of test equipment. I have only used Tek gear for oscilloscopes.
The engineers I have been associated with said "Tek make's scopes, HP makes everything else". It has served me well.
I had to look up the E7495 and from what little I could find the specs are only guaranteed from 375 MHz to 2.7 GHz. For what I do it would be almost worthless as most of my work is in the HF, VHF, & UHF range. It doesn't show a calibrated signal generator nor audio generators. It seems to me to be a very highly specialized cell test gear. I will be looking forward to your testing.
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One of the problems with the 8566/8568 is an aging CRT. These are getting a bit long in the tooth now and the CRTs get dim and unreadable at EOL. It is possible to rejuv the CRT and get some additional usable life. There are available LCD retrofits, however, that give new life to them and even add color.
Cons: big and heavy, CRTs are getting old
Pros: Complete service doc available, good specs, common faults repairable, LCD replacement available.
It is possible to find a display and an rf section and upgrade the display for somewhere around $1K.
If you do go for one of these, try to get a set with the interconnect cables included. They are often separated and the cables go for around $200/set when you can find them. It's possible to make up your own, but the connectors alone for the BNC cable run around $80, unless you find a deal on surplus parts. The bus interconnect cable is not a 1:1, but the pinout info is available in the service docs. It's a 50 conductor cable, though so it's a real pita to make up.
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There's also the Agilent E4406A which is a vector SA which goes to 4GHz but it only offers 10MHz span which is pretty poor. And it's essentially a SA only so it doesn't have any RF generator or other functionality.
Seems to be normal for a vector SA
It's not. Both the E7495A/B as well as the CMU200 are also Vector SAs but both offer a frequency span from zero to the full bandwidth, and still offer reasonable high refresh rates. As do most newer VSAs.
The reason the E4406A only supports 10MHz span is because it's awfully slow processing. I guess Agilent thought it's ok for the intended purpose (looking at GSM and CDMA signals) but then other comms testers don't suffer from this problem.
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If you have the space, then buy a 8566/8568. Best SA for the price (less than 500$ w/o shipping if you can wait and pick it locally).
Agreed, these are still the best SA for the price if you just want an old school analyser with high RF performance. I have one of each here but there are plenty of downsides IMO. They are very big and heavy and there is a lot of fan noise. As PaulAm says, the CRT ageing is also a significant problem. Also, overall reliability is becoming a serious issue with these old flagship analysers from HP.
I wouldn't consider buying any traditional spectrum analyser from Tek unless it was cheap and I was only needing mediocre performance.
I have always avoided the HP859x series of analysers and so has the company I work for. We have plenty of HP8560E thru 8563E and these are nice analysers although they are becoming very dated. However, They still cost well over £1500 (used) here in the UK even for a basic 8560E. So maybe these analysers are not in the running here because they typically cost a lot more than $1000.
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I have an old Advantest TR4172 here as well from the 1980s. It is an 1800MHz spectrum analyser with a tracking generator and it also has a factory option to allow impedance measurements with an external bridge from Wiltron. So it can be used as a basic VNA as well. I bought the first one about 10-12yrs ago for £400 and bought a 'spares' one for £250 about a year ago which is fully functional. It is a very good analyser but it is even bigger and heavier than the HP8568B. So it needs a very sturdy bench or trolley!
It was a serious contender against the legendary HP8568B in its day with quite similar performance :)
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Another con with the 8566/68 is if you need a tracking generator, you have to find an 8444a with option 059. These seem to have a minimum price of around $300-400 and it's another piece of gear to stack up
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I had to look up the E7495 and from what little I could find the specs are only guaranteed from 375 MHz to 2.7 GHz. For what I do it would be almost worthless as most of my work is in the HF, VHF, & UHF range. It doesn't show a calibrated signal generator nor audio generators. It seems to me to be a very highly specialized cell test gear. I will be looking forward to your testing.
I already mentioned the frequency range, and I suggested the E7495 only because the OP was asking for something up to 1.8GHz.
A bandwidth of up to 2.7GHz (E7495B, A variant is 2.5GHz) is also more than enough for lots of tasks as it covers a lot more than just cell phones (WiFi b/g/n, Bluetooth and other ISM stuff, ZigBee, DASH-7 and so on).
As to the E7495, the RF gen is certainly calibrated, and stability is pretty much excellent thanks to the built-in GPS reference. It doesn't have audio (but then the OP didn't ask for it!) but so don't standalone SAs. What it has is a Power Meter (requires an external measurement head, most Agilent standard types should do) which can be pretty handy. And unlike many other Comms Testers (i.e. Agilent 8960 Series 10) the E7495 is not "highly specialized", in fact unless you start one of the cell phone specific applications it looks and handles like any normal VSA, RF gen and Power Meter. The cable tester is useful as well, not only for profiling loss over the covered bandwidth but also for localizing defects (it can do 1-port and 2-port measurements). It can also measure Return Loss of cables, antennas and other RF parts. It runs Linux, and comes with USB, a PCMCIA and a CF slot, as well as a LAN interface, and Agilent offers some free program to control it remotely. The case is ruggedized for adverse environments and can certainly take some abuse.
The R&S CMU200 I also have is a bench/rack device, not a portable one like the E7495B. Mine does have audio (generator for up to 20 tones simultaneously plus THD and noise analyzer), the Reference OXCO option, two calibrated RF gens which also support various modulation types, a vector SA (10Mhz to 2.7GHz), a Power Meter (built-in), and aside from standard measurements can do a lot of other stuff. It also can be upgraded with various hardware options (i.e. I-Q analysis, Bluetooth analyzer).
Considering that the E7495B is from around 2010 I think it's a very good alternative to buying an old boat anchor like a HP 8568 which most certainly has long passed the zenith of its lifetime, and then invest even more money to keep it functioning. Don't get me wrong, these SAs were great in their days, but they are cheap because they are fragile and suck lots of power. This aside, even basic things like taking a screenshot is a pain in the arse with these old SAs. If you need the bandwidth (over 3GHz there aren't much alternatives if your budget is low) then it may be worth it, but certainly not if the requirement is 1.8Ghz of bandwidth.
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Since the E7495 asking prices seems to be around $2.5k, how relevant is this to the OP's question?
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IMO, if one really needed a proper SA, get a hp 8566/8568, deal with the space requirements and get a unit in good condition even if the cost is higher. These SA's remain excellent in many ways. Find a way to deal with the space requirements as any good SA is complex and large. If a portable is really needed, choose hp again.
Used the Tek 492 series when they were new. They were OK, just OK. Performance wise the hp SA's were simply better. These were "portable" and were originally designed to meet a US military contract requirement for a portable SA. Don't like Tek SA's in general.
What matters in SA's is noise performance, display dynamic range (must be over 100 db to be useful IMO) stability and lack of spurious response in the display.
Not impressed by low cost made in Asia offerings.
Bernice
'If you have the space, then buy a 8566/8568. Best SA for the price (less than 500$ w/o shipping if you can wait and pick it locally).
Agreed, these are still the best SA for the price if you just want an old school analyser with high RF performance. I have one of each here but there are plenty of downsides IMO. They are very big and heavy and there is a lot of fan noise. As PaulAm says, the CRT ageing is also a significant problem. Also, overall reliability is becoming a serious issue with these old flagship analysers from HP.
I wouldn't consider buying any traditional spectrum analyser from Tek unless it was cheap and I was only needing mediocre performance.
I have always avoided the HP859x series of analysers and so has the company I work for. We have plenty of HP8560E thru 8563E and these are nice analysers although they are becoming very dated. However, They still cost well over £1500 (used) here in the UK even for a basic 8560E. So maybe these analysers are not in the running here because they typically cost a lot more than $1000.
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Another con with the 8566/68 is if you need a tracking generator, you have to find an 8444a with option 059. These seem to have a minimum price of around $300-400 and it's another piece of gear to stack up
You can make your own tracking generator for and 8568 with some microwave lego from Mini Circuits a 1025MHz signal source and a 2-4GHz isolator.
Parts required are a frequency doubler to get 2050MHz from the signal source, a mixer (at least 2-3.5 GHz RF and LO, IF down to DC), the isolator (eBay) and some attenuators. You get 70dB or so dynamic range. Depending on your signal source, you may need a amplifier to drive the frequency doubler. The isolator is used to isolate the SA's 1st LO output or noise feeds back from the mixer and raises the noise level on the SA. I used the PA0KLT Kit E from sdr-kits for my signal source along with an amplifier to drive the frequency doubler. The Mini-Circuits parts have SMA connectors, so you also need an assortment of SMA and BNC adapters/cables.
I looked up the mini Circuits part numbers that I used:
Mixer: ZX05-C42-S+
X2 Multiplier: ZX90-2-11-S+
Broadband AMP: ZX60-43-S+
However, looking at the prices of these parts, finding an 8444A option 59 might be the better option. They can be found for less than $200 if you are patient.
It would be nice to sell the 8568 and get the Rigol DSA815, but the 8568 is so much better.
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One of the problems with the 8566/8568 is an aging CRT. These are getting a bit long in the tooth now and the CRTs get dim and unreadable at EOL. It is possible to rejuv the CRT and get some additional usable life. There are available LCD retrofits, however, that give new life to them and even add color.
The LCD upgrade is/will be available here: www.simmconnlabs.com/2001/2094.html (http://www.simmconnlabs.com/2001/2094.html)
I have a beta VGA version. Xu, the creator of this kit has done an incredible job. The display is way better than I'd expect for VGA resolution in its native mode. There is a video on the site that shows the different modes. It is also about one third of the price of the original LCD kits from other vendors! Last I heard, these kits should be available this month.
Disclaimer: no relationship other than being a very happy tester of this upgrade.
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Proving those Tek portable SA's did not stand the test of time.
Those hp Spectrum Analyzers work..
Bernice
I have a 496P. Front end mixer was blown (replaced with Mini-Circuits part). Phase lock was bad. Bad caps.... After repairs, works alright for what it is. Doubt you could get parts for it now. Would not pay $1000 for one. Make sure you can really check the thing out if you do go this route.
Also have an old HP8569A. Not good for low freq work. Made a converter for mine. Weighs a lot. GPIB control is pretty limited compared with the 496P.
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Since the E7495 asking prices seems to be around $2.5k, how relevant is this to the OP's question?
Who cares about the asking price? What matters is for what items are actually sold:
http://www.ebay.com/sch/i.html?_odkw=E7495B&LH_Complete=1&_from=R40&LH_Sold=1&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.A0.H0.XE7495&_nkw=E7495&_sacat=0 (http://www.ebay.com/sch/i.html?_odkw=E7495B&LH_Complete=1&_from=R40&LH_Sold=1&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.A0.H0.XE7495&_nkw=E7495&_sacat=0)
Only the ones which have the W-CDMA option fetch higher prices, but that option is irrelevant for using an E7495 as a standard SA/RF gen.
Finding one at a good price may require some patience but the same is true if you're shopping for an old boat anchor that doesn't already come as fixer-upper.
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Get a $10 tv stick from ebay and load up a sdr package - you have a spectrum analyzer.
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The E4406A are good because there were so many dumped on the second hand market that they are cheap and readily available. Good close in performance for looking at modulation, it's a shame that the span is limited to 10MHz
I've also got a pile of HP8594E. They are ok, but I really should develop a tracking generator for them. The 856X is a better analyzer but they're typically twice the price.
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Dang, I feel old.. more like a dinosaur, having a HP 141T :-[
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For example, have a loot at the Agilent E7495A/B. These are portable Base Station Test Sets which means you not only get a SA (500kHz to 2.7GHz, span from zero to full bandwidth) but also an RF generator (200MHz to 2.7GHz), a power meter, and (which is why many people want a tracking gen in the first place) a cable tester and TDR fault locator. It also has a GPS clock source. All in a sturdy ruggedized box that can take two rechargeable batteries and doesn't take much space on the bench (size-wise like a modern mid-range scope). They are a great bargain if you can find one with the right options below $1k (which with some patience is possible).
If I find the time I'll do a review of my E7495B over the weekend.
There are other alternatives, i.e. Anritsu MT8802A and Rohde & Schwarz CMU200. I have the latter, and it's a great device (mine has two RF gens, the audio analyzer, and the Reference OXCO).
The E7495B looks to be remarkable value if you can sometimes get them for around $1000. But I think you are being harsh against the HP8566/8 analysers.
These were fabulous analysers in their day and could be used for serious RF design work. I used both the 8568 and the TR4172 as design tools in the 1990s and the SFDR and close to carrier noise was superb on both of them. They are still very good even by today's standards.
Your two E7495B and CMU200 analysers would have been pretty much useless for the work I was doing back then if they had been sent back in time to me. It would be a bit like trying to dig up a concrete road with a plastic spoon because the close to carrier phase noise and SFDR are going to be pretty dire on both of them. So the analyser noise and SFDR would be far worse than the measurements I was trying to make.
But your E7495B analyser is portable and can do some modern tricks that the older analysers can't.
So when making a choice, a lot depends on what the analyser is going to be used for.
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The E4406A are good because there were so many dumped on the second hand market that they are cheap
Well, apparently not *that* cheap:
http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=agilent+e4406a&LH_Complete=1&LH_Sold=1&rt=nc (http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=agilent+e4406a&LH_Complete=1&LH_Sold=1&rt=nc)
More or less around the same as an E7495. I guess it depends if the additional 1.5GHz/1.3Ghz bandwidth are worth the bandwidth limit and the absence of RF gen.
Also, the E7495 is still supported by Agilent, while the E4406A isn't.
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The E7495B looks to be remarkable value if you can sometimes get them for around $1000. But I think you are being harsh against the HP8566/8 analysers.
These were fabulous analysers in their day and could be used for serious RF design work. I used both the 8568 and the TR4172 as design tools in the 1990s and the SFDR and close to carrier noise was superb on both of them. They are still very good even by today's standards.
I know very well how good they were (heck, I spent over a decade writing test software for RF ATEs which usually involved a HP 8566A/B).
But all the great specs don't change a fact that these devices have long been obsolete and that any of those that are still in working condition will very likely fail sooner rather than later. The 8568A is from around 1978, that's 37 years ago! Old HP kit was durable but there's a limit to what can be achieved after that time. Aside from the increased failure probability, there's a lot of stuff that doesn't age well, and unlike modern devices these SA's do actually require adjustment to stay within their specs.
BTW, if I remember right the 8568A/B goes to 1.5GHz only anyways, so wouldn't even fit the OP's requirement (1.8GHz).
Your two E7495B and CMU200 analysers would have been pretty much useless for the work I was doing back then if they had been sent back in time to me. It would be a bit like trying to dig up a concrete road with a plastic spoon because the close to carrier phase noise and SFDR are going to be pretty dire on both of them. So the analyser noise and SFDR would be far worse than the measurements I was trying to make.
That's all very interesting but I believe we're trying here to suggest something that's right for the OP and not something that would have worked for you some 20 odd years ago, so frankly it's irrelevant if you could have made your measurements with the suggested kit modern back then or not. Back in the day I probably would have said take the HP kit but the OP lives in the here and now and clearly has different requirements, which seems to be a limited budget and 1.8Ghz required bandwidth, so he has to deal with the decision if he wants something modern (which means VSA) or an 25+ year old swept SA which due to the age alone comes with its own problems.
And quite frankly, if I compare the specs of the HP 8568A and the E7495B then the latter actually looks pretty good compared to the old kit:
http://www.dudleylab.com/hp8566-s.pdf (http://www.dudleylab.com/hp8566-s.pdf)
https://www.atecorp.com/ATECorp/media/pdfs/data-sheets/Agilent-E7495A_Specs.pdf (https://www.atecorp.com/ATECorp/media/pdfs/data-sheets/Agilent-E7495A_Specs.pdf)
For example, frequency stability or displayed average noise level is better with the E7495. Much better.
The CMU200's specs also don't look too shabby:
http://cdn.rohde-schwarz.com/pws/dl_downloads/dl_common_library/dl_brochures_and_datasheets/pdf_1/CMU200_dat-sw_en.pdf (http://cdn.rohde-schwarz.com/pws/dl_downloads/dl_common_library/dl_brochures_and_datasheets/pdf_1/CMU200_dat-sw_en.pdf)
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And quite frankly, if I compare the specs of the HP 8568A and the E7495B then the latter actually looks pretty good compared to the old kit:
http://www.dudleylab.com/hp8566-s.pdf (http://www.dudleylab.com/hp8566-s.pdf)
https://www.atecorp.com/ATECorp/media/pdfs/data-sheets/Agilent-E7495A_Specs.pdf (https://www.atecorp.com/ATECorp/media/pdfs/data-sheets/Agilent-E7495A_Specs.pdf)
For example, frequency stability or displayed average noise level is better with the E7495. Much better.
The CMU200's specs also don't look too shabby:
http://cdn.rohde-schwarz.com/pws/dl_downloads/dl_common_library/dl_brochures_and_datasheets/pdf_1/CMU200_dat-sw_en.pdf (http://cdn.rohde-schwarz.com/pws/dl_downloads/dl_common_library/dl_brochures_and_datasheets/pdf_1/CMU200_dat-sw_en.pdf)
But look at the phase noise:
8568B is -100dBc at 3kHz, -107dBc at 30kHz.
E7495 is -85dBc at 30kHz; compare against the Rigol DSA815's -80dBc at 10kHz.
8566B is -90dBc at 10kHz but it's unfair to compare the '66B since that spec is for center frequency to 5.8GHz.
I look at these and stick with the 8568A. If I want frequency accuracy, I can hook up the GPSDO to the 8568A and use its internal frequency counter. FWIW, the 8568A/B will go over 1.7GHz with reduced accuracy and there is an option, H17 that makes the 1.7GHz limit official.
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And quite frankly, if I compare the specs of the HP 8568A and the E7495B then the latter actually looks pretty good compared to the old kit:
It's risky and often misleading to look at shortform datasheets when assessing a spectrum analyser. Also, it depends which parts of the spec matter. If you want to check the close to carrier noise on a VHF synthesiser then the 37 year old HP8568 is still a very good analyser because it was designed for stuff like this. Your analysers are not. eg the HP8568 typically manages a close to carrier noise performance of about -112dBc/Hz at a 300Hz offset at the lower part of its frequency range. This makes it an extremely powerful tool for synthesiser design, testing or faultfinding. I'd expect your analysers to be of limited use for this type of work.
Your analysers would also not be very good in terms of harmonic or IM distortion or general spurious performance.
To get reasonably accurate measurements of harmonic distortion the analyser's own internally generated harmonic distorion term needs to be about 15-20dB lower than the level of the harmonic to be measured. So stuff like this ideally needs a very strong analyser front end in order to keep measurement uncertainty within reasonable limits if trying to measure fairly low levels of harmonic distortion fairly accurately.
But your analyser(s) still might still be a better overall choice for the OP. It depends on what type of measurements and features (eg stuff like portability) matter most. I'm just offering my professional opinion based on many years' experience of using many of the classic high end spectrum analysers found in RF labs over the last 25 years or so right up to using the latest offerings from Agilent/KS.
Some of these 'classic favourite' analysers are available for very little money today (which is what this thread is about). I paid £125 for my HP8568B about 6-8 years ago.
I paid £400 for my Advantest TR4172 over 10 yrs ago and recently bought another for £250 as a backup or for a cheap source of spares.
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But look at the phase noise:
8568B is -100dBc at 3kHz, -107dBc at 30kHz.
E7495 is -85dBc at 30kHz; compare against the Rigol DSA815's -80dBc at 10kHz.
8566B is -90dBc at 10kHz but it's unfair to compare the '66B since that spec is for center frequency to 5.8GHz.
Yes, the phase noise is better on the 856xB. How critical this is depends on what you want to do, though. And the better phase noise is simply worthless if the bandwidth is too low for the OP's requirements.
Also, don't forget that the HP 85xx Series is mostly analog, and while these SAs had very good specs when they were new there's a good chance that after 30 odd years many of the units offered on ebay need at least serious re-alignments to reach their original specifications, or even component replacement. I certainly wouldn't blindly trust a 30yr old SA unless it has been recently calibrated, no matter who built it.
If I want frequency accuracy, I can hook up the GPSDO to the 8568A and use its internal frequency counter.
Which means another box and investment for the OP who already said he's on a tight budget.
FWIW, the 8568A/B will go over 1.7GHz with reduced accuracy and there is an option, H17 that makes the 1.7GHz limit official.
But 1.7GHz is still not the 1.8GHz the OP wants, and even if it were it's no good if the SA's bandwidth ends right at the upper frequency you want to look at.
It's risky and often misleading to look at shortform datasheets when assessing a spectrum analyser.
I am well aware that the specs aren't telling everything but what they do show is that the modern kit does noticeably better in certain aspects that the oldtimer. Other problems like scale fidelity also don't even exist on the modern kit.
Your analysers would also not be very good in terms of harmonic or IM distortion or general spurious performance.
I'm not sure they would be that bad (the specs I found for the E7495 seem to be a bit sparse so I have no hard figures). In some areas they might not be as good as these old HP SAs but they seem to be still better than cheaper modern SAs like the Rigol DSA800, which are widely used despite performing worse in some areas than the mentioned HP 8568s. And at the moment we don't really know what the OP wants to do, all we know is that he's looking for an SA covering 1.8GHz and at below $1k, which isn't much information.
But your analyser(s) still might still be a better overall choice for the OP. It depends on what type of measurements and features (eg stuff like portability) matter most.
Indeed. I think the OP should be a bit clearer in what he actually wants to do with the SA, as so far it's more a game of guess as to what properties would be the most important.
I'm just offering my professional opinion based on many years' experience of using many of the classic high end spectrum analysers found in RF labs over the last 25 years or so right up to using the latest offerings from Agilent/KS.
Some of these 'classic favourite' analysers are available for very little money today (which is what this thread is about).
As I said, I know very well how good these old HPs were (as you, RF is part of my work for over 25 years, although mostly in higher bands so I'm more familiar with the 8566B than with the 8568 SAs). But I also do know very well how fragile these old SAs are (they already were back in the days!), and am under no illusion that for someone who wants something that "just works" on a shoestring budget these old dinosaurs can quickly turn into a huge money pit. If you're prepared for that and have the means to fix it then fine, but I didn't get the impression that the OP was able or willing to dive into a fixer-upper project.
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Looks like it's more sane to buy DSA815, then spend on used bulky equipment. I see only one issue with DSA815 : it starts from 9 KHz, so you can't really use it for audio applications =(
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Looks like it's more sane to buy DSA815, then spend on used bulky equipment. I see only one issue with DSA815 : it starts from 9 KHz, so you can't really use it for audio applications =(
I struggle to see how they could get the phase noise that poor.
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The Advantest R3131 could also be a good option (9kHz to 3GHz).
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Looks like it's more sane to buy DSA815, then spend on used bulky equipment. I see only one issue with DSA815 : it starts from 9 KHz, so you can't really use it for audio applications =(
Well, I see two other issues: the DSA815 goes to 1.5GHz only when the OP wanted 1.8GHz, and the price is roughly $1500 when the OP's limit is $1k.
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The Advantest R3131 could also be a good option (9kHz to 3GHz).
They're good units, and the last few I had sold quickly, but I see very few of those for sale in the wholesale market.
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How good are HP 8562A ? They appear to be about 15 years old and should still hold up well; they aren't quite boat anchors either.
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A Spectrum Analyzer is probably the last bit of bench gear, I have always wanted by have never gotten around to getting.
And, now I can't decide if I should get a used HP/Agilent or just get a RIgol.
The used HP/Agilents are going for about $1500, and you can get a new Rigol for the same thing with the tracking generator included, lots of computer connectivity etc..
I think the prices on the HP/Agilents need to come down. It wont be long before people realize that there is a better option at that price level than the old HP boat anchors. If the prices come down to $500-$1000(with a TG included) maybe I might consider a good used one, otherwise I will plan on getting a new rigol.
Heck in a coupe of year, Rigol will probably have new models that blow the existing ones out of the way and the used gear will look even more expensive in comparison. You might even start to see some used Rigols on the market too pushing the prices down.
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Very little wrong with the hp 141T system, had a system decades ago complete with storage normalizer, tracking gen, preselector and several RF plug ins including the LF plug in. It served fine as the lab SA for a very long time.
It is so very easy to discount and discard the capability of older SA systems like this when in fact the still are extremely useful and good instruments in every way. One thing memorable about the hp 8555A, 0.01 to 18 Ghz plug in was low noise and the signal ID switch, even if one had to keep track of the numerous spurious response blips that appeared which had to be verified as real.
While newer SAs offer better performance in some areas and automation with abilities to interface to a computer, these features do not make them automatically better than older SAs like the 141T system. It depends on what the measurement needs are.
As for fragile SA inputs, user needs to be aware and careful to prevent input mixer and related damage. Often this is just not that difficult to prevent zapping the SA input.
Bernice
Dang, I feel old.. more like a dinosaur, having a HP 141T :-[
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Curious, how bad is the phase noise (real world conditions, not as spec'ed) is the DSA815?
Sweep-ed spectrum analyzers are not the ideal choice for audio-low frequency work. There are far better ways and instruments for that measurement need today.
Bernice
Looks like it's more sane to buy DSA815, then spend on used bulky equipment. I see only one issue with DSA815 : it starts from 9 KHz, so you can't really use it for audio applications =(
I struggle to see how they could get the phase noise that poor.
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Thanks for the good discussions – it’s very informative and helpful. I appreciate all the posts and hopefully they will help others here read or search in the future for spectrum analyzer advice.
Regarding the budget, this is for an amateur/educational endeavor so the budget is driven by what is feasible/practical and not by an absolute figure ($1k is just a benchmark). The budget could be higher and of course it would be nice to go lower but it isn’t going to provide a financial return on investment (as a professional application would) so this spectrum analyzer goes in the nice/want to have bucket vs. the need to have bucket. - So maybe we could set the price aside for a while and look at possible specs and features. Plus, others might have a different budget so I’m inclined not to rule out anything on price just yet – at least until I can better understand the price/performance tradeoffs. Having said that, in my case it’s hard to imagine spending over $2k and at that I would have to have my head examined. :palm:
Regarding bandwidth, 1.8 GHz is not an absolute, it could be 1.5 GHz or elsewhere in the 1-2 GHz range. However, if it were possible to get to 2.5 GHz that would reach the Wifi range and if BW could get to 5 GHz that would be even better for Wifi. (Although perhaps with harmonics even more BW is needed?) Obviously, as the bandwidth goes up so does the price – but let’s set the price aside for the time being.
Regarding RBW, it would be good to get smaller increments than 9 kHz. Getting to below 100 Hz would be great to cover audio. On the other hand, if the price uplift (I know I said we were going to set that aside) is too great to cover audio then maybe a separate solution (PC sound card?) might make sense for audio. I had a sense for these tradeoffs before my original post but all the discussions have now surfaced these tradeoffs and more with better clarity.
Regarding possible equipment it seems there isn’t a lot confidence in some of the vintage models. The Tek 49x series looks cool but it doesn’t get a lot of love here. Likewise for the Tek 27xx series? Perhaps as avvidclif said "Tek make's scopes, HP makes everything else". I’m not ready to rain on Tektronix’s parade (I love their analog scopes) but I get the idea that not everything has to be Tek.
The HP units seem to come in at least 3 possible series: 856x, 859xE, and 859xL.
There is also Wuerstchenhund’s Agilent E7595A/B which looks very interesting; I’m inclined to set it aside for a moment and declare it a finalist that can be compared against one or a few other finalists. I’m also inclined to put the Rigol DSA815-TG in the final consideration bucket too. Let's put Rupunzell's HP 141T on the finals table too - it looks gorgeous in a vintage kind of way. :) So the question is what other used equipment might outperform these two models on value (ie, price, functionality, and performance; reliability will also ultimately become an important consideration to be made – but for now let’s assume that a good working condition used unit can be found if someone searches hard enough).
In the 859xL series are some contenders:
8590L 9 kHz – 1.8 GHz
8594L 9 kHz – 2.9 GHz dc coupled (100 kHz – 2.9 Ghz ac coupled) - probably going to stress the budget
According to the HP specs both offer RBW of 1 kHz to 3 MHz in a 1,3,10 sequence.
In the 859xE series are some contenders:
8591E 9 kHz - 1.8 GHz
8594E 9 kHz - 2.9 GHz
8595E 9 kHz - 6.5 GHz
According to the HP specs all three offer RBW of 30 Hz to 3 MHz with 10 Hz Nominal.
In the 856X series are contenders:
8560A 50 Hz – 2.9 GHz - probably going to stress the budget
8561B 50 Hz – 6.5 GHz - probably going to break the bank
According to the HP specs both offer RBW of 10 Hz to 1 MHz in a 1,3,10 sequence and 2 MHz.
Any thoughts on the tradeoffs among the above models? (The 8591E, 4E, and 5E look like very good price performers.)
Beyond frequency range and RBW are a bunch of other specs and considerations. Phase and SFDR measurement performance seem to be worthy considerations. Any other considerations on buying criteria and potential models are very welcome.
Thanks, EF
PS, I'm kind of in the same boat with what nixfu says in his post above - I'm betting there are others in this boat too so the wisdom from the experienced users is definitely appreciated.
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For audio I'd get an audio analyser or a scope with a good FFT function. An audio analyser is likely to include features like determining harmonic distortion (THD) etc.
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I think the prices on the HP/Agilents need to come down. It wont be long before people realize that there is a better option at that price level than the old HP boat anchors. If the prices come down to $500-$1000(with a TG included) maybe I might consider a good used one, otherwise I will plan on getting a new rigol.
The Rigol DSA800 is primarily one thing - cheap. If you want a brand new device then the DSA800 is certainly worth considering. But aside from the price there's nothing spectacular on the Rigol. It's specs are somewhat OK, and feature-wise it's pretty simple. As others said any of the old HP boat anchors will (when working) easily out-perform the Rigol DSA.
Heck in a coupe of year, Rigol will probably have new models that blow the existing ones out of the way and the used gear will look even more expensive in comparison.
I don't think so. Rigol's main feature has always been the price, and they are pretty successful with their kit. It never has been performance, though, aside from the fact that most Rigol kit suffers from some or several firmware problems that seem to be pretty standard with Chinese brands' kit. Just look at their pathetic offerings on mid-range scopes. Or the DSA1000 Series of Spectrum Analyzers.
I can see Rigol pushing down prices somewhat for other entry level gear but not for second hand mid-range and high-end kit.
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For audio I'd get an audio analyser or a scope with a good FFT function. An audio analyser is likely to include features like determining harmonic distortion (THD) etc.
Indeed. An audio analyzer can also be found in some Communication Testers. For example, R&S CMU200 I have came with the optional two channel audio analyzer which also includes two separate LF generators (multi-tone capable).
Below are some screenshots showing the main menu, the analyzer with a 10kHz sine on applied (via a crappy BNC lead), the multi-tone analyzer and the THD analyzer.
Much more useful for audio stuff than a SA in my opinion.
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Late to the party but a comment on the Tek 2700 series mentioned by the OP.....
I own a Tektronix 2710 SA and was initially pleased with it. My Advantest SA's at that time were the R4131D units and I used the 2710 for TV signal work. The 2710 then suffered corruption in the character generator so some display text was unreadable.Such a fault is common on these units. This failure was soon followed by PSU failure. After a Re-cap and the failure of several PSU key components, I have to recommend against buying an elderly 2710 SA.
My 2710 is presently sat under my bench in disgrace as I can't get the enthusiasm to dive into the PSU to repair it. It will likely end up sold on ebay as a project for someone else.
Aurora
UK
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Don't forget to include the old TR4172 in the mix... This was the mega expensive flagship analyser from Advantest/TR that could compete with the best from HP in the 1980s. It covers up to 1800MHz and has a tracking generator. It also has an internal preamp option (not a particularly good one though), a 1000 x 1000 data point display (via CRT) and it has a 'real' frequency counter built in at the IF and this measures with up to 10digit resolution. (eg 1Hz at 1GHz).
It's OCXO frequency reference has less ageing/drift per YEAR (at +/- 0.02ppm) than the basic short term accuracy spec claimed for the Agilent E7495A even with help from GPS.
It's mixer IP3 is typically about +22dBm (compared to about +13dBm for a HP8568B or +9dBm for the HP8566B)
It's phase noise at 100kHz offset is about -128dBc/Hz. This is about 13dB better than a HP8568B.
It also has a factory option to allow impedance measurents if you use the tracking gen and an external return loss bridge from Wiltron. So it can be used as a basic VNA for impedance measurements once calibrated. I don't think any other analyser mentioned so far on the thread can measure impedance with a TGen and external RLBridge. This level of performance still outclasses most modern analysers.
The major downside is that it is a huge and heavy boatanchor and mine lives on a trolley as it is bigger/heavier than the HP8568B. The major plus point is that they are often very cheap to buy if you can find one. I recently paid just £250 for one :)
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Depending on how the upcoming new software release holds up, I'd be inclined to consider the Signal Hound SA44B at $919 over the Rigol 815. The SA44B goes up to 4.4GHz, but does need a PC to run its software. The associated tracking generator is $599. You'd want the $40 accessory kit whatever - I'd want the DC block and an attenuator permanently connected.
I actually considered a Signal Hound when I got the 8568B. I don't regret getting the HP.
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For what its worth, I've got a HP8595E which I obtained for a stupidly low price when my employer was selling some surplus kit. I don't know a great deal about them not being an RF boffin but wanted one and this was too good an opportunity to turn down. Speaking to the engineers that used to use it, they all praised it and said it still compared well performance wise to the newer equipment that had replaced it.
I also got a HP ESA-L1500A at the same time, also for a stupidly low price (I got both together for probably less than you're budgeting for one!).
They're both a bit bulky, they're both a bit noisy (fan wise), but they look like they'd survive the apocalypse unlike my Rigol scope which despite being awesome for the price just seems so much more fragile.
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I managed to buy a pair of Advantest R3132 SA's for GBP600 each so there are good buys to be had out there. The R3132 makes my R4131's seem very antique and basic but I still love their ease of use and the capabilities that I have when remote controlling the R4131 via GPIB ;D
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It's OCXO frequency reference has less ageing/drift per YEAR (at +/- 0.02ppm) than the basic short term accuracy spec claimed for the Agilent E7495A even with help from GPS.
The TR4172's frequency stability is pretty good and as you say could easily compete with HP's best SAs back in the days. The E7495 can't reach that but still comes close (<+0.03ppm with GPS locked), but the R&S CMU200 with option B12 (Reference OXCO) does quite a bit better short-term (+0.005ppm).
But I'd say the TR4172 is one of the few old timers that may be worth investing in if you can use it's advantages, even though the problems with almost 30yr old kit are still valid. And because it's not a HP or Tek they are usually pretty cheap.
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Yes, the OCXO inside the TR4172 is a huge thing and is very expensive.
The ageing spec over 1 day is +/-0.0005ppm according to the OCXO manufacturer's data sheet. i.e. < +/- 5E-10. This is pretty good even by today's standards.
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Yes, the OCXO inside the TR4172 is a huge thing and is very expensive.
The ageing spec over 1 day is +/-0.0005ppm according to the OCXO manufacturer's data sheet. i.e. < +/- 5E-10. This is pretty good even by today's standards.
It is. I guess it's part of the reason the TR4172 was excessively expensive back in the days, even compared with its HP counterparts.
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The Tektronix 492 was originally designed and intended for a US military contract. Tek eventually got this contract and became sole supplier for this specific type of SA for the US military. Ailtech-Eaton (Cutler-Hammer) filed a protest to zero avail.
Standard US military issue for SA back in the 1970's was hewlett packard 141T system (any wonder why there were SO many of these around) and the Tektronix 491.
http://www.gao.gov/assets/430/421442.pdf (http://www.gao.gov/assets/430/421442.pdf)
Bernice
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What is the meaning of the letters (A, B, C, L, others?) in the HP 859X series?
What are the key tradeoffs between the 856X series and the 859X series?
What is preferred for a tracking generator? An integrated TG, or for some reason an external TG (such as the 85640A?); I'm inclined to save space an go with integrated...
How valuable/nice/useful is the split screen feature?
Anyone have a link to something that shows the history/evolution/production dates of the HP spectrum analyzer products?
Thanks!
Update: answered part of my own question here:
http://www.testunlimited.com/pdf/an/5968-2602E.pdf (http://www.testunlimited.com/pdf/an/5968-2602E.pdf)
https://groups.yahoo.com/neo/groups/hp_agilent_equipment/conversations/topics/27032[/url
(https://groups.yahoo.com/neo/groups/hp_agilent_equipment/conversations/topics/27032)
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Keeping in mind this application is for "learning", here are some more thoughts and questions:
What defines "real time" in a spectrum analyzer?
http://www.radio-electronics.com/info/t_and_m/spectrum_analyser/analyzer-types.php (http://www.radio-electronics.com/info/t_and_m/spectrum_analyser/analyzer-types.php)
According to this article SA's can be classified as:
Swept spectrum analyser
FFT spectrum analyser
Real-time spectrum analyser
Is the Rigol DSA815 a "real time" SA?
Are the Agilent 8560E and 8590E "real time"?
The article states:
Both swept / superheterodyne and FFT analyzer technologies have their own advantages. The more commonly used technology is the swept spectrum analyser as it the type used in a general-purpose test instruments and this technology is able to operate at frequencies up to many GHz. However it is only capable of detecting continuous signals, i.e. CW as time is required to capture a given sweep, and they are not able to capture any phase information.
FFT analyzer analyser technology is able to capture a sample very quickly and then analyse it. As a result an FFT analyzer is able to capture short lived, or one-shot phenomena. They are also able to capture phase information. However the disadvantage of the FFT analyzer is that its frequency range is limited by the sampling rate of the analogue to digital converter, ADC. While ADC technology has improved considerably, this places a major limitation on the bandwidths available using these analyzers.
In view of the fact that both FFT and superheterodyne / swept instrument technologies have their own advantages, many modern analyzers utilise both technologies, the internal software within the unit determining the best combinations for making particular measurements. The superheterodyne circuitry enabling basic measurements and allowing the high frequency capabilities, whereas the FFT capabilities are introduced for narrower band measurements, and those where fast capture is needed.
An analyzer will often determine the best method dependent upon factors including the filter settling time and sweep speed. If the spectrum analyser determines it can show the spectrum faster by sampling the required bandwidth, processing the FFT and then displaying the result, it will opt for an FFT approach, otherwise it will use the more traditional fully superheterodyne / sweep approach. The difference between the two measurement techniques as seen by the user is that using a traditional sweep approach, the result will be seen as sweep progresses, when an FFT measurement is made, the result cannot be displayed until the FFT processing is complete.
Swept or superheterodyne spectrum analysers: The operation of the swept frequency spectrum analyzer is based on the use of the superheterodyne principle, sweeping the frequency that is analysed across the required band to produce a view of the signals with their relative strengths. This may be considered as the more traditional form of spectrum analyser, and it is the type that is most widely used.
Fast Fourier Transform, FFT analysers: These spectrum analyzers use a form of Fourier transform known as a Fast Fourier Transform, FFT, converting the signals into a digital format for analysis digitally. These analysers are obviously more expensive and often more specialised.
Real-time analysers: These test instruments are a form of FFT analyser. One of the big issues with the initial FFT analyser types was that they took successive samples, but with time gaps between the samples. This gave rise to some issues with modulated signals or transients as not all the information would be captured. Requiring much larger buffers and more powerful processing, realtime spectrum analyser types are able to offer the top performance in signal analysis.
How relevant are these distinctions and considerations to the selection of an "entry level / first-time / learning" SA?
(On the one hand it's hard to imagine ever buying a second SA so it would be good to get a unit that will go the distance (5-10 years or longer?) but it's also hard to justify extra $ for something that is a nice-to have rather than a need-to have).
Other considerations:
If you have a SA, a Tracking Generator would be pretty useful, yes?
It seems like the 8560E will outperform the 8590E in various specifications but the 8590E might have more automated capabilities to facilitate testing. This might not be a perfect analogy but I've found that a Tek 2247A scope is sometimes more enjoyable to operate because of the way it employed "early" microprocessor technology and therefore measurements and readouts are sometimes more accessible and better labeled on screen than it's more highly specified big brother 2465/7B. I'm wondering if the user interface on the 8590E might make it a better "learning" tool? On the other hand the RBW and many of the specs on the 8560E are superior. Either way, one of these (actually a 8560E or a 8594E, either with a built-in TG) would seem to be a contender.
The downside of the 8560/90 is that for a rookie there could be any number of issues I wouldn't find until after purchasing a supposedly good unit. Might be too much complexity/reliability risk and cost to invest in a "learning" SA. They aren't "vintage" but they might be just slightly long in the tooth.
Having said that, I am enamored with Bernice's much older 141T (it seems like it just barely escaped the vacuum tube era to make it into the transistor era - just kidding, sort of). It probably has the simplest user interface and it's the oldest and maybe the least likely to keep working but it seems like they can be found for $500 or less and it has a ton of bandwidth - but no Tracking Generator.
Then there is still the Rigol. And the E7495B. And the 8568A/B.
I know, it would be good to start by pinning down some constant: price, functionality, performance, ease of use, reliability, etc. :-//
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Keeping in mind this application is for "learning", here are some more thoughts and questions:
How relevant are these distinctions and considerations to the selection of an "entry level / first-time / learning" SA?
(On the one hand it's hard to imagine ever buying a second SA so it would be good to get a unit that will go the distance (5-10 years or longer?) but it's also hard to justify extra $ for something that is a nice-to have rather than a need-to have).
Other considerations:
If you have a SA, a Tracking Generator would be pretty useful, yes?
The downside of the 8560/90 is that for a rookie there could be any number of issues I wouldn't find until after purchasing a supposedly good unit. Might be too much complexity/reliability risk and cost to invest in a "learning" SA. They aren't "vintage" but they might be just slightly long in the tooth.
Having said that, I am enamored with Bernice's much older 141T (it seems like it just barely escaped the vacuum tube era to make it into the transistor era - just kidding, sort of). It probably has the simplest user interface and it's the oldest and maybe the least likely to keep working but it seems like they can be found for $500 or less and it has a ton of bandwidth - but no Tracking Generator.
I know, it would be good to start by pinning down some constant: price, functionality, performance, ease of use, reliability, etc. :-//
Good article BTW.
There were a few different tracking generators for the 141T. I had one that was good to a little over a GHz.
A tracking generator would be useful and allows you to make scalar network measurements. Looking at a filters transfer function for example. There is no phase information.
The 3589A is a single channel vector network analyzer (phase information is added). There is an S-parameter set available for it but I don't have one. I have played with using an external directional coupler with it. Limited because the software needs to detect the test set before some of the features are enabled.
If you are buying used, your point about not finding a problem until after the purchase is valid, rookie or seasoned. Maybe you could get some help checking out a used one if you go that route.
Personally, if learning is the goal, the suggestion of making your own a while back is a good way to go. The comment about using a TV is tuner can make it really cheap. The cost will be next to nothing and you will understand how it all works when you are done. Maybe then look at buying an OTS system.
http://www.qsl.net/n9zia/spec/w6hph.pdf (http://www.qsl.net/n9zia/spec/w6hph.pdf)
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Another way of learning about this Super-het radio stuff is to get a copy of Ron Quan's book about radios. Read it and build a few of them to gain a basic understanding of how this Super-Het stuff and radios work. With this knowledge and understanding gained, how and what a swept SA does and works will begin to make a lot more sense. If radios are built, further understanding and knowledge can be gained by applying a SA to example radios. This entire journey can teach a lot about not only radio technology, but about instrumentation set up and what the resulting data could mean and how to interpreter it.
http://www.edn.com/electronics-blogs/anablog/4405264/Book-review--Build-your-own-transistor-radios (http://www.edn.com/electronics-blogs/anablog/4405264/Book-review--Build-your-own-transistor-radios)
As for an FFT example, consider a sound card with FFT software. These are often good enough to provide a working example of FFT analyzers.
There were a good number of audio RTA (aka, bank-O-filters & display) produce and sold in mass for the consumer audio market. Get of of these if an example of an RTA analyzer is wanted.
Bernice
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What is the meaning of the letters (A, B, C, L, others?) in the HP 859X series?
What are the key tradeoffs between the 856X series and the 859X series?
The 859X do have 80 dB dynamic range on screen vs. 100 dB for the 856X... and the 856X have lower phase noise and a RBW down to 1 Hz vs 1kHz(?)...
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How relevant are these distinctions and considerations to the selection of an "entry level / first-time / learning" SA?
It simply depends on what you want to do. Swept SAs were pretty much the oldest type of commercial SAs (FFT aka Vector SAs came much later due to the processing required), and as you stated correctly are generally the way to go if you need to cover large bandwidths (i.e. 2-25GHz).
If you don't need large bandwidths then a VSA becomes a viable option, and some of the advantages you listed (i.e. better for pulsed signals) can be pretty useful. And since VSAs are usually younger units they will statistically have more life left in them, and because they are fully digital they also support internal self-calibration and diagnostics which means they keep their specs for a very long time without requiring regular adjustments.
(On the one hand it's hard to imagine ever buying a second SA so it would be good to get a unit that will go the distance (5-10 years or longer?) but it's also hard to justify extra $ for something that is a nice-to have rather than a need-to have).
Honestly, how likely is it that any 30+ yr old SA you buy today, no matter how great, will still be in use by you 10 years down the line? Most of the stuff in those old boat anchors is already obsolete today, and most parts in it will also be pretty close to the end of it's useful life.
And frankly, with the relative low prices for some used kit it's in my opinion much more sensible to buy what you need now and, when you reach the device's limitations, to sell it on and buy a better device. This of course assumes that your first SA won't be a money pit which requires you to invest a multiple of the purchase price to keep it working.
Other considerations:
If you have a SA, a Tracking Generator would be pretty useful, yes?
If it's a swept SA, yes (VSAs don't have tracking generators because they're not swept). But again it depends on what you want to do. If you want to test cables, filters or transmission lines with a swept SA you'd want a tracking gen. Some VSAs like the E7495 which have an RF gen built in can do that as well.
I know, it would be good to start by pinning down some constant: price, functionality, performance, ease of use, reliability, etc. :-//
A good start would be to think long and hard what you actually want to achieve, what bandwidth you need, and what parameters (i.e. specs, reliability, supportability) are most critical to you. And then you just filter the suggestions for adherence to your requirements.
As long as you haven't properly formulated your requirements I'd say follow joesmith's and Rupunzel's advice and try some sound card or TV tuner with SA software as a cheap learner. This way you're less likely to waste your money on something that's not right for you.
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Ok, still sorting out the big buckets of categories:
Large bandwidth (for example, 2-25GHz) might dictate a swept SA.
Less bandwidth (how much less or across what range?) might dictate or make practical a VSA?
Where/what is the distinction between VSA and real-time SA? What bandwidths are typically provided by real-time SAs?
Is a Rigol DSA815TG a swept analyzer and not a VSA or a real-time analyzer since it uses a tracking generator?
In addition to the E7495 what are other less than $3k VSAs?
If there is a distinction between a VSA and a real-time analyzer, are there real-time SAs for less than $3k?
I saw the article below; it indicates that any SA that is a VSA is effectively a real-time analyzer; is that a fair statement? Thanks
Realtime FFT
Most modern spectrum analyzers are now almost exclusively Hybrid Superheterodyne-FFT based giving a significant improvement in sweep time. However, even in such cases there is still processing time required to sample the spectrum and calculate the FFT. For this reason, both swept-tuned and FFT based analyser produce "blind time" meaning that while calculation of the spectrum is being performed, the instrument has gaps and misses information of the RF spectrum being applied to the RF front end.
A realtime spectrum analyser does not have any such blind time—up to some maximum span, often called the "realtime bandwidth". The analyser is able to sample the incoming RF spectrum in the time domain and convert the information to the frequency domain using the FFT process. FFT's are processed in parallel, gapless and overlapped so there are no gaps in the calculated RF spectrum and no information is missed.
Online realtime and offline realtime
In a sense, any spectrum analyzer that has vector signal analyzer capability is a realtime analyzer. It samples data fast enough to satisfy Nyquist Sampling theorem and stores the data in memory for later processing. This kind of analyser is only realtime for the amount of data / capture time it can store in memory and still produces gaps in the spectrum and results during processing time
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Non-realtime vs realtime FFT analyzer is really a marketing distinction to highlight the higher processing power (and thus faster update rate) of the realtime ones. From a technical point of view it's essentially the same.
I dunno what you intend to do exactly and while realtime analyzers are really cool in general they're also really expensive (since they're newer)..
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Is a Rigol DSA815TG a swept analyzer and not a VSA or a real-time analyzer since it uses a tracking generator?
It's a swept SA, like all the low end SAs. That's how they reach the low price. Swept SAs are generally simple to build and don't require powerful processing or much memory as a VSA does.
In addition to the E7495 what are other less than $3k VSAs?
I assume you're talking about 2nd hand prices (even the E7495B was north of $8k when new a few years ago)? There are several VSA only devices, like the Agilent E4406A. However, in my opinion some of the Wireless Communications Tster (which essentially are VSA + RF gen + other stuff in one unit) like the Agilent E7495A/B, the R&S CMU200 or some Anristu units are much more interesting as they can do more than just being an SA.
I saw the article below; it indicates that any SA that is a VSA is effectively a real-time analyzer; is that a fair
Yes. "Real-time" is more a marketing term for fast VSAs than a real distinction. It's generally used for high end VSAs.
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So, other than price are there any advantages to a swept SA vs a VSA?
And just to confirm, a 8560E/8590E are swept?
New question, any advantage to a 8560E with an external 85640A TG vs. an internal TG?
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The second my even cheaper and less useful SA that took longer to build out of junk. LEDs for the mixer diodes, a few old crystals make up the filter and a glass diode for the detector. :palm:
Do you have any measured result for this you can share? What kind of conversion loss did you get from it?
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The second my even cheaper and less useful SA that took longer to build out of junk. LEDs for the mixer diodes, a few old crystals make up the filter and a glass diode for the detector. :palm:
Do you have any measured result for this you can share? What kind of conversion loss did you get from it?
No. This was only to show that you could build something very low cost to learn how an SA works.
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There was an HP 8560E in working condition sold on an auction site for $769.09 plus 16% buyers premium. Looked very nice and had the Cal seals intact.
Would I buy that over a Rigol? In a heartbeat any day. Besides the fact it goes to 2.9GHz.
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There was an HP 8560E in working condition sold on an auction site for $769.09 plus 16% buyers premium. Looked very nice and had the Cal seals intact.
Would I buy that over a Rigol? In a heartbeat any day. Besides the fact it goes to 2.9GHz.
That's an amazing deal... :) We still use the 8560E in our design labs today. However, for that price I'd expect there to be a few niggles with it.
Deals like that don't happen very often but give it a few more years and they will become more commonplace.
I've not used the Rigol or the test sets like the R&S or the E7495A but experience has taught me to run a mile from cheapo test sets if you want decent RF performance on the bench. I'd expect the E7495A performance to be a bit woeful if subjected to a few basic analyser benchmark tests. Not something I would want unless it was for field/portable use where its performance limitations are less important.
One thing to add in favour of buying the big old HP8566 or HP8568 analysers is that spares are now plentiful on ebay and, contrary to what the 'hund claims, this type of analyser could therefore prove reasonably cheap to maintain as long as the user has reasonable diagnostic/repair skills.
I've got a HP8568 and a 8566 plus two TR4172 analysers and they all work and so far the repair/maintenace costs are less than the cost of a few drinks for all of them. I bought the 8568 for £125 many years ago from the company and I don't think it has ever failed since it was donated to the company on a contract over 25 years ago. It's a similar tale for the TR4172. It was donated to the company about 25 years ago and I bought it about 10yrs ago. It's repair costs have been close to zero in all this time. I bought a second TR4172 as a spares donor for it for £250 from someone in London and this cost me nothing to repair so it is a cheap spares/backup unit.
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So, other than price are there any advantages to a swept SA vs a VSA?
And just to confirm, a 8560E/8590E are swept?
New question, any advantage to a 8560E with an external 85640A TG vs. an internal TG?
Everything from that era is swept. Well, actually, not quite. The 8560E switches to FFT for resolution bandwidths below 300 Hz, IIRC, while the 8590E with the narrow bandwidth option uses analog filtering all the way down to 30 Hz. This means that if you want to use a tracking generator with an RBW of less than 300 Hz, you cannot use an 8560E, only an 8590E. Not sure if this is a concern or not.
As far as tracking generators are concerned, you can get external generators such as the 85644A (300k to 6.5G) and 85645A (300k to 26.5G) but these require a LO signal from the analyzer. The 8560E series includes a LO out by default for use with external mixers. However, the 8590E does not - you either need the LODA option 009 or the tracking gen option 010 to get a LO out SMA connector on the back panel. However, the internal tracking gen only covers the low band up to 2.9 GHz. You need an external tracking gen if you want to go above that.
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would an Anritsu MT8820A be suitable? 2.7Ghz bandwidth 25Mhz span and seemed to be quite fast and responsive when I last used it or are they more locked down to cdma/gsm type testing? I have one of these I am looking to offload.
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I've not used the Rigol or the test sets like the R&S or the E7495A but experience has taught me to run a mile from cheapo test sets if you want decent RF performance on the bench.
I'm not sure what you consider "cheapo" but the E7495 Series did cost somewhere excess of $18k which isn't exactly 'cheap' in my book.
The R&S CMU200 price varied a lot (there are tons of options for it) but some configurations went for in excess of $100k, The naked base was somewhere around $35k if I remember right.
As an example:
http://shop.rohde-schwarz.com/bargain/r-srcmu200-15.html (http://shop.rohde-schwarz.com/bargain/r-srcmu200-15.html)
(look at the original price)
Not all Mobile Comms Tester are of the primitive kind of an Agilent E6392B or Racal 6103 which really are very simple devices.
Both the E7495 and the CMU200 were certainly not 'cheap' by any means, especially not for below 3GHz RF kit. And those prices aren't even ancient (the E7495B was EOL'd I think in 2012 and the CMU200 in 2010).
And that old SAs like the 8568 have more RF pipework in them is more due to the 30+yrs difference in technology than any performance differences.
I'd expect the E7495A performance to be a bit woeful if subjected to a few basic analyser benchmark tests.
Maybe, maybe not. Don't forget that this is a device that is designed for maintaining and repairing BTS systems, i.e. complex transmission systems which also are the cell provider's backbone. You can't get very far with just a scope and a detector diode on these systems, you need a proper SA and RF synthesizer for that.
If you have a certain test in mind (and if I can reproduce it in my limited home lab) then let me know and I'll try it on my E7495B.
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By cheap I mean the RF components used in the E7495A spectrum analyser will be cheap. The RF synthesiser will be crude, noisy and cheap. The filters used in it will be cheap with less than spectacular stopband performance. The active devices will be low power and cheap resulting in reduced dynamic range.
I'd be interested to see how the E7495A performs in terms of signal handling and synthesiser noise. One basic test would be to put a small signal in at -120dBm and view it on a narrow span then and put in another much bigger signal at about 1MHz away but 120dB bigger at 0dBm and see if the analyser can still display the little signal without losing it in noise or blocking/overload. An old school lab analyser from 35 years ago can pass this test with some margin. Depending on how well the E7495A does then I can make the test tougher.
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By cheap I mean the RF components used in the E7495A spectrum analyser will be cheap.
I wouldn't count on that.
I'd be interested to see how the E7495A performs in terms of signal handling and synthesiser noise. One basic test would be to put a small signal in at -120dBm and view it on a narrow span then and put in another much bigger signal at about 1MHz away but 120dB bigger at 0dBm and see if the analyser can still display the little signal without losing it in noise or blocking/overload. An old school lab analyser from 35 years ago can pass this test with some margin. Depending on how well the E7495A does then I can make the test tougher.
Sure, I can give it a try (when I found my box with RF couplers).
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I wouldn't count on that.
Well, you have used the E7495B and I haven't.
But basic business sense tells me that the E7495B will have been designed by Agilent to be a cost effective solution that allows technicians to do fairly basic site surveys of base stations using a hand portable analyser.
The DSP back end will presumably have a decent capture BW allowing various kinds of signal analysis/verification. That's where the strengths of the instrument lie. But there really won't be much point making the RF downcoverter of this 'signal analyser' have the same RF performance as a top of the line lab grade spectrum analyser.
To do this would mean making it very big, expensive, heavy and power hungry and it would price itself out of the market.
I would expect it to have a fairly basic synthesiser and fairly modest IF filtering and a low cost construction to achieve the basic design goals.
Looking through its specs there is a spec for crossing spurs at -50dBc. Although this spec is a bit vague I suspect that this will be a clue as to the limitations of the IF filtering (SAW filter?) and some of these spurious terms will be alias terms. But I'm just guessing.
Here's a plot of my old HP8568B showing a deliberately added spurious term at about -90dBc on a 62MHz signal that is 400Hz from the carrier. The analyser noise is actually much lower than the noise on the plot as the 90dB log display is the weak link here. Normally I would alter the ref level to get the spur and the noise inside the log range. But the noise performance here is very good for such an old analyser.
Can you post up a plot showing a carrier on a 2kHz span on your E7495B? I'd expect it to be a lot noisier.
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Here's an old plot of the input return loss of the 8566 RF port with the default 10dB attenuator selected.
The VSWR would therefore be about 1.05:1 or better across most of the range up to 2.5GHz where the input image filter begins to degrade the match. Having a low VSWR helps a lot with overall measurement uncertainty.
It's pretty impressive stuff from the big old dinosaur?
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I wouldn't count on that.
Well, you have used the E7495B and I haven't.
So far I haven't used it much aside from a few basic measurements, though, mostly due to time constraints. I'm also not suggesting it performs as good as a HP 8568A/B, but I would be surprised if it's not noticeably better than the Rigol DSA830 or other SA's in that price range, so if these are considered good enough for hobbyist use then the E7495 and similar VSAs should be as well.
But basic business sense tells me that the E7495B will have been designed by Agilent to be a cost effective solution that allows technicians to do fairly basic site surveys of base stations using a hand portable analyser.
It's built for a bit more than just basic site surveys (there's another Agilent device for that), it's really designed for onsite fault finding and diagnostics. Also don't forget that with VSAs the RF part can be noticeably simpler than with an analog swept SA.
The DSP back end will presumably have a decent capture BW allowing various kinds of signal analysis/verification. That's where the strengths of the instrument lie. But there really won't be much point making the RF downcoverter of this 'signal analyser' have the same RF performance as a top of the line lab grade spectrum analyser.
Certainly not but I'd still expect it to show some good performance compared with a standalone unit in the same frequency band.
Here's a plot of my old HP8568B showing a deliberately added spurious term at about -90dBc on a 62MHz signal that is 400Hz from the carrier. The analyser noise is actually much lower than the noise on the plot as the 90dB log display is the weak link here. Normally I would alter the ref level to get the spur and the noise inside the log range. But the noise performance here is very good for such an old analyser.
It is, but also never said that RF performance was a problem with these old analyzers. It's age (and with it the high probability of failure), fragility, size, power consumption and the lack of basic secondary functionality (making screenshots for example ;) ) that are the negatives in my opinion.
Can you post up a plot showing a carrier on a 2kHz span on your E7495B? I'd expect it to be a lot noisier.
Sure, I'll do some tests over the weekend. If anything it's a nice chance to compare this thing (and my CMU200) with a standalone swept analyzer.
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It is, but also never said that RF performance was a problem with these old analyzers. It's age (and with it the high probability of failure), fragility, size, power consumption and the lack of basic secondary functionality (making screenshots for example ;) ) that are the negatives in my opinion.
It is possible to take fairly decent screen plots/shots via the GPIB port with a USB to GPIB cable on all of my old analysers. My TR4172 is the analyser I use most and see below for a screenshot showing the 2nd harmonic distortion level of the analyser. I've used the freebie KE5FX plot utility to get this plot.
I've fed a very clean 28MHz signal in from a E4433B sig gen via a 30MHz LPF so the 2nd harmonic on the signal fed into the analyser is << -100dBc. So it's a very clean signal source.
The signal into the analyser is 0dBm and there is 10dB of internal attenuation so the analyser's mixer is seeing -10dBm and the displayed internal 2nd harmonic is -90dBc. I don't think there is any phase cancelling going on here to give a false result. Down at the VHF end of its range the analyser has very good signal handling properties. The local oscillator amplifier for the first mixer is a huge module that spits out about +22dBm to drive the high level 8 diode mixer.
Can you put a clean 28MHz signal into your E7495B analyser at 0dBm drive and 10dB attenuation and see how much distortion it shows as a comparison?
Note that the high noise level on the main black trace is caused by the relatively poor phase noise of the E4433B signal generator I used for this test.
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You can also do higher resolution screenshots with these old analysers.
The display has 1000 x 1000 datapoints inside the grid area so each box in the grid has 100 x 100 data points in system memory.
The plot below is the highest resolution that the plotter program can go to but I think the analyser is better than this... The analyser can do 1000x1000 inside the grid area and the image below is only 1024x768 for the whole image so the plot still looks a bit grainy.
(making screenshots for example ;) )
Can you show a screenshot from your modern E7495A analyser with finer screen resolution than this 35 year old technology?
I suppose I could try writing my own plotter capture program. The TR4172 allows full access to all system memory via GPIB so I should be able to grab the 1000x1000 grid data and produce a nicer image still...
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I suppose I could try writing my own plotter capture program. The TR4172 allows full access to all system memory via GPIB so I should be able to grab the 1000x1000 grid data and produce a nicer image still...
You don't need to, its been done, you need the GPIB toolkit, go here....
http://www.ke5fx.com/gpib/readme.htm (http://www.ke5fx.com/gpib/readme.htm)
Or alternatively if you want to part with a few $ and get serial coms too, try PrintCapture...
http://www.printcapture.com/ (http://www.printcapture.com/)
I use that to get screen captures from my HP 54720D scope and HP E6380 test set.
Here' some output I've recently captured using GPIB toolkit's plotter emulator from my HP8566B
cheers
Tim
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It is possible to take fairly decent screen plots/shots via the GPIB port with a USB to GPIB cable on all of my old analysers. My TR4172 is the analyser I use most and see below for a screenshot showing the 2nd harmonic distortion level of the analyser. I've used the freebie KE5FX plot utility to get this plot.
Yes, I know, but that requires an external computer. It's much more convenient if you can just press a button and the SA saves a screenshot to the plugged in CF card.
Can you put a clean 28MHz signal into your E7495B analyser at 0dBm drive and 10dB attenuation and see how much distortion it shows as a comparison?
Sure. Unfortunately my only 28MHz source at the moment is a Rigol DG1062z, but I managed to do a really quick test today.
I fed the 0dBm (according to the Rigol's display, didn't check how accurate it is) via a Huber & Suhner BNC-to-N adapter connected to a Spectrum cable (2-18GHz) to a Mini-Circuits 10dB 6GHz attenuator sitting on the E7495B's input. The attenuator might be suspect, though, as I found it in a box and haven't had time to check it out.
It's not the best config but that was all that I could find in the short time available.
I'll see if I can do some more tests tomorrow, which could also include an R&S CMU200.
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Here' some output I've recently captured using GPIB toolkit's plotter emulator from my HP8566B
cheers
Tim
That 8566 plot looks really good with very fine detail. I think I'm still using an old version of the KE5FX toolkit or maybe I'm not getting the best from it. I'll try downloading the latest version.
This is my HP3589A, shown with -100dB, spur 6Hz off the carrier.
Wow, the 3589 looks good there!
The old 8568B can manage -112dBc/Hz phase noise just 300Hz from the carrier at the lower end of its tuning range but it can't go below 10Hz RBW...
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Yes, I know, but that requires an external computer. It's much more convenient if you can just press a button and the SA saves a screenshot to the plugged in CF card.
USB/Flash is the modern solution but on my older gear I get pretty good results using a (highly portable) mini EEPC netbook and a USB/GPIB cable as a wireless 'dongle' to my test gear that is mapped as a wireless network drive to my main PC. This way I can access the plots remotely as they appear instantly on my main PC. Usually I have the USB/GPIB cable connected to a common GPIB bus to all my test gear so I can get plots or control the test gear via the little EEPC and the wireless network link.
I use the same system when creating S2p models with my VNA as I can extract the s parameter data from the VNA using the EEPC and then it appears instantly on the main PC via wifi.
The EEPC holding the plots or S2p files pops up as a shared network folder on the main PC via wifi. The latest plots or files pop up first in the file list making it a reasonably powerful solution :)
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Hey joeqsmith,
Well that's impressive - whats that written in ?
thanks
Tim
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Here are some screenshots of the 28MHz 0dBm sine from a Rohde & Schwarz CMU200.
I used a different cable (standard RG-58 BNC) with H&S BNC-to-N adapter and another 10dB attenuator.
The input attenuator of the CMU200 has three operation modes (Normal, Low Noise, Low Distortion) so I captured the results in all three modes.
Let me know if you want to see any other tests. Unfortunately I can't do things like the two tone test suggested by G0HZU as I don't have a suitable power combiner at the moment (and not the time to build one).
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Hopefully you can now see how noisy the basic LO synthesiser is in the E7495A as it performs very poorly in all the tests.
The plots from the R&S test set look a lot better but I think that if you measured the carrier noise at 100kHz, 500kHz and 1MHz it would not be in the same class as an old school lab analyser. There will be compromises made here because this is a test set and not a lab grade spectrum analyser.
The same applies for spurious performance and signal handling. If I had both test sets here I think I could find aspects of the RF converter performance that are severely compromised when compared to a dedicated analyser. Obviously, the test set has a modern DSP back end and a host of other tools and features that don't even exist on an old school analyser but if (like me) you want to do fairly serious RF design then test sets are not the tool of choice as they are too compromised in terms of the raw RF performance they offer in the converter section.
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There will be compromises made here because this is a test set and not a lab grade spectrum analyser.
Yes, but I never said that they are. But reality is that not everyone needs the performance of a high end SA, and both sets are still better than what I've seen from a Rigol DSA830.
All I wanted to do is to show that there are alternatives between these old high end SAs and the Rigol, and if you can live with their performance then they might be a reasonable option, and without the size, power consumption and reliability issues of the old kit.
I can see the E7495 as a great tool for someone starting with RF stuff, as it's a not just a VSA but also a RF generator/AWG and a Power Meter (although you need a measurement head), is compact and can often be found for little money.
The other thing is that the E7495 is running Linux, and that there's a huge potential to hack it into a nice unversal portable test set for other stuff than cell phone testing.
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For serious RF-Microwave folks, performance of the RF sections matter most. Extra features offered by DSP are never going to make up for a RF section with limited performance.
It might be worth noting that a good spectrum analyzer is a absolute requirement for communications RF and microwave work as they can provide information and test data that a time domain instrument can not. Different tool for a different job.
And yes, that hp 8568 looks as good as ever. BTW, one good old hp 8568 was used to develop one of the many cameras that is currently living on the Mars rover Curiosity.
Bernice
Hopefully you can now see how noisy the basic LO synthesiser is in the E7495A as it performs very poorly in all the tests.
Obviously, the test set has a modern DSP back end and a host of other tools and features that don't even exist on an old school analyser but if (like me) you want to do fairly serious RF design then test sets are not the tool of choice as they are too compromised in terms of the raw RF performance they offer in the converter section.
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Hey joeqsmith,
Well that's impressive - whats that written in ?
thanks
Tim
Thanks. That was done with Labview 5.
Yes, very impressive!
You should do a youtube demo
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You can also do higher resolution screenshots with these old analysers.
The display has 1000 x 1000 datapoints inside the grid area so each box in the grid has 100 x 100 data points in system memory.
The plot below is the highest resolution that the plotter program can go to but I think the analyser is better than this... The analyser can do 1000x1000 inside the grid area and the image below is only 1024x768 for the whole image so the plot still looks a bit grainy.
(making screenshots for example ;) )
Can you show a screenshot from your modern E7495A analyser with finer screen resolution than this 35 year old technology?
I suppose I could try writing my own plotter capture program. The TR4172 allows full access to all system memory via GPIB so I should be able to grab the 1000x1000 grid data and produce a nicer image still...
Is it actually stored as a 1000x1000 grid or is it stored as a vector? My guess is a vector, not a grid (1000 points at 1000 possible levels per point) - this is how the 856x series analyzers work, and why the display is so much crisper than the 859x series. Anyway, if you want "native res" for vector, what you need to do is store it as a vector file like an svg. I have been working on some Python code that translates HPGL read out of an analyzer to XML and writes it out as an SVG file. It works with the trace from my 8593E, and it should work for other instruments as well, possibly with some bug fixes. You can then open the svg in a vector graphics editor like Illustrator or Inkscape and play around with it, or export it as a raster file like PNG. (It's actually not terribly difficult to convert HPGL to SVG, the existing plotting software is horribly complex because it actually renders the HPGL to a raster format instead of just converting it)
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Hey joeqsmith,
Well that's impressive - whats that written in ?
thanks
Tim
Thanks. That was done with Labview 5.
Yes, very impressive!
You should do a youtube demo
Thanks. The start of this video shows my home made discriminator that I use with that particular Labview program. If you would like, I could show how to make a measurement with it.
https://www.youtube.com/watch?v=4rJcEVj8OYo (https://www.youtube.com/watch?v=4rJcEVj8OYo)
I'd be very interested to see that if you have the time to do it. The discriminator looks very interesting and you have built it very well!
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Is it actually stored as a 1000x1000 grid or is it stored as a vector? My guess is a vector, not a grid (1000 points at 1000 possible levels per point)
I'm afraid that I can't answer your question very reliably as I've never tried to capture screen images with my own code but I think it is possible to access any part of the system memory via GPIB.
So I think I could dump a string from the analyser containing the trace memory.
I think the start address for the trace memory is 0xC018.
I'd expect to be able to dump 1000 memory points from here where each point takes up two bytes.
In the byte pairs would be a data value from 0000 to 03E8 in hex where 3E8 = 1000 in decimal. If it was 3E8 then it would be at the top of the grid and zero would be at the bottom. But all this is just guesswork looking at the user manual.
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It would be interesting to see it measure and plot phase noise and see how far down it can measure using this method. But please only do this if it is convenient for you and doesn't take up too much time...
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Is it actually stored as a 1000x1000 grid or is it stored as a vector? My guess is a vector, not a grid (1000 points at 1000 possible levels per point)
I'm afraid that I can't answer your question very reliably as I've never tried to capture screen images with my own code but I think it is possible to access any part of the system memory via GPIB.
So I think I could dump a string from the analyser containing the trace memory.
I think the start address for the trace memory is 0xC018.
I'd expect to be able to dump 1000 memory points from here where each point takes up two bytes.
In the byte pairs would be a data value from 0000 to 03E8 in hex where 3E8 = 1000 in decimal. If it was 3E8 then it would be at the top of the grid and zero would be at the bottom. But all this is just guesswork looking at the user manual.
There isn't a command to just read the raw trace data directly? That would seem like a very odd omission.
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I had a go at dumping raw trace data from the TR4172 memory.
It does seem to be arranged as 1000 pairs of bytes each holding a value up to about 03E8.
The analyser allows the data to be dumped out very efficiently so the plot below takes a fraction of a second to appear. Obviously I haven't bothered to add the scaling or other onscreen text but it shows the raw trace data against a basic grid background.
I think I might take this further because I think I can get about 5 screen dumps a second with my code and this is in contrast to the KE5FX toolkit plotter that takes maybe 20 seconds to grab just one screen plot :)
There isn't a command to just read the raw trace data directly? That would seem like a very odd omission
I'm not really sure if I'm dumping the info correctly or not. But there is a command that allows the trace to be dumped out as a huge string or a set of strings. I think I can dump out any memory address range in any size chunk I choose. However, the manual appears to have been produced by a dyslexic japanese to english translator and there are quite a few typos in the manual wrt the relevant commands to control the analyser via GPIB :)
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With my 8593E, you can just send TRA? and it will spit out the data points. There are a couple of other options to change the data format to binary or ASCII as well. It's rather the whole point of the remote interface, I would think. I presume there is a similar command for your analyzer as well, though it may be hard to find.
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You may want to have a look at CERN's program. I have used this for several years to convert HPGL files and it works great.
http://service-hpglview.web.cern.ch/service-hpglview/download_index.html
(http://service-hpglview.web.cern.ch/service-hpglview/download_index.html)
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The corrected video is up.
https://www.youtube.com/watch?v=GP6B_ImnoII (https://www.youtube.com/watch?v=GP6B_ImnoII)
The video is about 25 minutes long. The attached picture shows the end results. Blue trace is the measured phase noise and Green is the noise. Also shown are the calculated values from the simulation allowing you to compare the results.
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raising the bar above $1k...
Anyone have experience with both the 8560E (or other same series models) and the Agilent E4400 Series (E4403, E4402B, etc.), or have any insights/thoughts on how the 856XE compares to the E44XXB? The specs might be better on the 856XE but the user interface might be better on the E44XXB? (I noticed in a couple of videos it looks like w2aew uses a E4411B.)
PS, joeqsmith - very cool posts, I'd be happy and honored to share this thread with you :) - please keep posting your excellent work!
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The corrected video is up.
https://www.youtube.com/watch?v=GP6B_ImnoII (https://www.youtube.com/watch?v=GP6B_ImnoII)
The video is about 25 minutes long. The attached picture shows the end results. Blue trace is the measured phase noise and Green is the noise. Also shown are the calculated values from the simulation allowing you to compare the results.
That looks very good, thanks for doing the video. The noise floor limit does look to be quite good :)
The only phase noise measuring capability I have here at home is via my TR4172 and HP856x spectrum analysers but I'm lucky to have access to a couple of Agilent E5052A SSAs at work. I keep meaning to make something for home use but never get around to it.
In the meantime I'm hoping that one of the works E5052A analysers will fail and be declared BER and I'll have a chance to buy it cheaply :)
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Anyone have experience with both the 8560E (or other same series models) and the Agilent E4400 Series (E4403, E4402B, etc.), or have any insights/thoughts on how the 856XE compares to the E44XXB? The specs might be better on the 856XE but the user interface might be better on the E44XXB? (I noticed in a couple of videos it looks like w2aew uses a E4411B.)
At work we have dozens of lab grade analysers and we also have some of the E4407 type analysers. These don't offer the same RF performance as the HP856xE analysers but they do have a more modern user interface and a fresher looking display.
The E4407 analysers we have at work have an optional self cal routine that makes an annoying cheepy/chirpy noise each time it runs. A bit like there is a small hatchling bird inside singing for food when it gets hungry every few minutes. You can't hear it in a big noisy lab but in a small room it is very noticeable and I find it very distracting :)
It can be turned off in the menus after it has warmed up but this is at the risk of losing some accuracy over time.
The E4407 is also a very good looking and nicely built analyser and it is quite easy to move around (not that heavy) and has very chunky rubber support blocks around its extremities giving it a reasurringly robust feel.
They tend to get used for field trial work or for basic verification tests. Especially by people doing basic system testing or faultfinding. But for serious RF design work the HP856xE analysers are much better in terms of the raw RF performance. eg noise and spurious performance and overall measurement uncertainty.
But top dog at work are the E444x PSA analysers and we also have a few PXA analysers although some of these may be rented. I'm assuming that you aren't including the E444x in your list as these are very expensive. I'd like to have one here at home but can't justify the cost of a used one :)
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Thanks for the comments. I realized after making the video that I never showed the final jitter number and I am sure I missed some other details. Hopefully there were enough details that people will have some idea of how this measurement is made.
The only phase noise measuring capability I have here at home is via my TR4172 and HP856x spectrum analysers ..
The Advantest looks to have a fair amount of features. The 3589A can also display complex data using an external coupler. The problem with it (besides the limited BW) is that their internal software is crippled without having a real test set connected.
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On the Agilent E7495B, does any one know if the option 510 CE signal generator is a tracking generator or just a single frequency?
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On the Agilent E7495B, does any one know if the option 510 CE signal generator is a tracking generator or just a single frequency?
Product brief calls it a "reverse link signal generator" for several cell network standards. So it seems to be a modulated CW source of some sort, not a tracking generator.
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On the Agilent E7495B, does any one know if the option 510 CE signal generator is a tracking generator or just a single frequency?
Product brief calls it a "reverse link signal generator" for several cell network standards. So it seems to be a modulated CW source of some sort, not a tracking generator.
Yup. That's what I saw on the data sheet as well, but it's a different wording on the installed option screen of the device. So, thought I would ask.
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On the Agilent E7495B, does any one know if the option 510 CE signal generator is a tracking generator or just a single frequency?
The E7495 is a VSA (Vector Spectrum Analyzer) which works by FFT and not by sweeping what essentially is a superhet receiver, and since there is no frequency sweep there can't be a tracking generator.
The E7495 has three signal generators. One is standard (a swept generator used for the Insertion/Return Loss measurements), and option 510 enables the other two, a CW generator (option 500) and an Arbitrary Waveform Generator.
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D'oh! I knew that for earlier in the thread. I think I can pick one up for less than $1000 US. Any issues to look out for?
What features will be missing from the spectrum analyzer versus say an 8593E? I know that the latter will be more sensitive and more accurate, but will the handheld be missing essential analysis tools?
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D'oh! I knew that for earlier in the thread. I think I can pick one up for less than $1000 US. Any issues to look out for?
What features will be missing from the spectrum analyzer versus say an 8593E? I know that the latter will be more sensitive and more accurate, but will the handheld be missing essential analysis tools?
Depends on what you need. The E7495's SA frequency coverage starts at 500kHz but below 375MHz the noise floor is higher than above that due to the input amplifiers (can also be seen on the screen shots I posted a while back which show signals below 375MHz; still had no time to do some more thorough tests with mine). Functionality-wise it's the same as any SA. You get 5 markers (although only one can be read out at any given time), manual and automatic scaling, manual and automatic RBW settings. There are other goodies like a Spectrogram or measurements for Occupied Bandwidth (OBW) which can be useful.
The frequency accuracy of the E7495 is also pretty good, especially when GPS stabilized. And if you wanted a TG for checking cables and filters then the E7495 can do that as well. And having all that in a relative compact format that doesn't take much desk space and is ruggedized is a bonus. As is a display that can even be read in full daylight.
One of the drawbacks is the limited remote control capability. There's no SCPI or stuff like that, there's only a JAVA GUI (actually the same GUI as on the device itself) which requires an antique and insecure JRE (1.4) to work.
Generally I'd say if a Rigol DSA830 would do the job for you then the E7495 should be fine. Just be aware that the E7495A only goes to 2.5GHz while the E7495B goes to 2.7GHz.
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D'oh! I knew that for earlier in the thread. I think I can pick one up for less than $1000 US. Any issues to look out for?
What features will be missing from the spectrum analyzer versus say an 8593E? I know that the latter will be more sensitive and more accurate, but will the handheld be missing essential analysis tools?
I'd expect the E7495 to be really, REALLY slow when trying to display large frequency spans.
I'd also want to know if it allows the user to control the video bandwidth and if it has a 1Hz noise marker feature. I'd also be very concerned about the -50dBc crossing spurs spec. This is in toytown territory and underlines the fact that the E7495A is merely a site survey tool aimed at technicians and not a dedicated spectrum analyser aimed at serious lab use.
However, just as I would normally run a mile from low performance test sets like the E7495A I would also run a mile from an HP8593E. There are much better choices out there for just a little more money.
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What would you recommend?
I'm nervous about the Linux portable set just because of my experience with an Anritsu portable which had the slowness on wide sweeps but was totally useless when it came to saving data to disk or a USB stick.
The specs on the 7495 aren't too bad. The noise floor is pretty darned good for a portable.
I'm also looking at a 9340A which has a higher noise floor but I believe is a swept analyzer with a traditional tracking generator.
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I can only really choose the correct analyser for 'me' because I don't know what you will be using it for or what you expect from it. So it would be risky for me to choose :)
However, Agilent produced an analyser guide a while ago
"Select the Right Agilent Signal Analyzer for Your Needs"
You can find this at MRTestequipment.com with a google search and it covers the PSA, ESA-E, HP859x and HP856xE models plus many more. There's also a newer version of this document here:
http://cp.literature.agilent.com/litweb/pdf/5968-3413E.pdf (http://cp.literature.agilent.com/litweb/pdf/5968-3413E.pdf)
But this is for the latest models
At work we use the PSA and the HP856xE models in the design labs. But the HP856xE models are quite dated now and only really 'shine' in terms of the phase noise and spurious performance. But I still like these analysers a lot.
The ESA E range is a mid range analyser that is very good all round compromise but they aren't cheap to buy for home/hobby use.
I think most people would be happiest with the ESA-E models or the Rigol 1500MHz or 3GHz offerings because they offer modern connectivity and a decent display and user interface.
But they are all going to cost more than I have ever spent on a spectrum analyser for home use so I do wonder why so many people on here are buying expensive stuff like this. I do RF design for a living but I still don't buy £££ test gear for home use. I don't think any item of test gear I've bought for use at home cost more than about £1000.
I'd like a decent VNA to replace my old HP8714B so I'm likely to smash the £1000 barrier in style at some point but I'm hoping to buy an ex works VNA (eg a faulty one that is BER) to keep the price sensible.
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Watched this video last night. Excellent post.
EEVblog #575 - DIY 1970s Spectrum Analyser
https://www.youtube.com/watch?v=579SYLxORyw (https://www.youtube.com/watch?v=579SYLxORyw)
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What is particularly impressive is the fact he's done it all with discrete parts that anyone can salvage at lowish cost (and he did it way back in the 1970s !).
Back in the 1980s there were various designs floating around for homebrew analysers that worked alongside a scope. I can remember that these used ICs for things like the log stage and the mixers.
Building a spectrum analyser is a great way to learn about RF design (or at least it was in my day). There's a bit of everything in there including system design and frequency planning, oscillator design, filter design, amplifier and detector design and mixers too... :)
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I'd expect the E7495 to be really, REALLY slow when trying to display large frequency spans.
The following are taken from a really quick test, handstopped (time is period between screen refreshes):
Span 500kHz to 2.7GHz:
RBW 1MHz: 1s
RBW 100kHz: 5s
RBW 10kHz: 6,5s
RBW 1.4kHz: 33s
Span 1GHz to 2.7GHz:
RBW 1MHz: 0,5s
RBW 500kHz: 0,8s
RBW 100kHz: 2,2s
I'd also want to know if it allows the user to control the video bandwidth
No, it doesn't. Because it's a VSA, not a swept SA. And on a VSA the role of the VBW is taken over by FFT averaging, and that can be controlled manually on the E7495.
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The slow sweep time would hamper testing of, say, an amplifier that was showing intermittent instability out of band. A conventional analyser can sweep a 2.5GHz span in a few milliseconds. I think my HP8566B does it in 0.02 seconds meaning that instability and rapid changes/peaking in the noise that herald the onset of an unwanted amplifier oscillation can be spotted really easily as the display looks really fluid.
A lot of reasonably modern analysers that get classed as swept types can also behave as VSA with suitable SW running on a PC. i.e. they offer the best of both worlds with a VSA BW of 10MHz or more. These have user controls for video bandwidth as and when required and can also provide VSA functionality as and when required with the use of suitable software (from Agilent).
Does the E7495A offer a (1Hz RBW) noise marker function? This is something I would consider essential on a modern analyser for correct analysis of noise signals. AFAIK the Rigol analysers offer this as a standard feature although I don't know how accurate their system is or if it offers the same noise marker performance/features of the classic lab analysers from the big names.
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The slow sweep time would hamper testing of, say, an amplifier that was showing intermittent instability out of band. A conventional analyser can sweep a 2.5GHz span in a few milliseconds. I think my HP8566B does it in 0.02 seconds meaning that instability and rapid changes/peaking in the noise that herald the onset of an unwanted amplifier oscillation can be spotted really easily as the display looks really fluid.
Yes, the 8566B can be pretty fast, especially with option 002, considering that it has over 20GHz bandwidth it better has to be. However, and it's been a while since I last used one, but if I remember right sweeping a 2.6GHz span with the shortest sweep interval (IIRC 20ms) will result in uncalibrated results.
Also, don't forget that a VSA doesn't sweep, i.e. during each acquisition it measures the full selected span, not just a moving window like a swept SA. And while a swept SA requires a short sweep time to capture intermittent signals, this isn't equally true for a VSA.
A lot of reasonably modern analysers that get classed as swept types can also behave as VSA with suitable SW running on a PC. i.e. they offer the best of both worlds with a VSA BW of 10MHz or more. These have user controls for video bandwidth as and when required and can also provide VSA functionality as and when required with the use of suitable software (from Agilent).
As I said, the E7495 doesn't have video bandwidth controls because these only exist on swept spectrum SAs but not on VSAs. VSAs do the same with FFT Averaging, and that setting can be changed on the E7495.
And yes, of course you can do FFT on a separate PC connected to an old SA like the 8566B, and if you can live with having a huge box of 50kg and with a volume of somewhat half a m^3, sucking roughly 650W (and even in Standby it's still around 40W!) while producing a lot of noise, plus a PC, and if you can live with a 30+yr old instrument that is fragile and needs regular adjustment to stay within specs, and where most parts have been obsolete 10 years ago already, then I'd say go for it. These old SAs are great.
However, for those that don't have the space, and want something that is compact, fast and reliable for a limited bandwidth, then devices like the E7495 are much more attractive than the outlook of an old antique on live support. Which is the reason why the market for SAs not only consists of large high end analyzers with 20+GHzs bandwidth, and why there are quite a few portable units. It's not a one size fits all.
Generally dismissing portable units like the E7495 because they don't perform as well as a huge high end lab SA is a bit silly, really. Not every task requires the bandwidth or the absolute performance of a calibrated and fully working 8566B, like not everyone needs a 5+GHz scope. Often enough the lower performance of such portable units is more than good enough. The E7495 doesn't perform badly, it has quite a bit of phase noise, but on the other side frequency stability is really good (even better than for the 8566B!), as are the values for DANL, and sensitivity isn't that bad, either. It's certainly more than just a toy.
The other thing is that the E7495 is not just a SA. It's also a RF generator, a Power Meter, a simple 2-port Network Analyzer (amplitude only though, not phase), and a cable fault localisator. To get the same functionality with an old swept SA like the 85xx Series you have to stack more expensive boxes (Tracking Generator, VNA bridge, Power Meter) on top of the already large SA, which takes up more space, more money, more energy, and introduces more points of failure into already fragile equipment. And still it's utterly worthless once you need to take the setup with you out in the field. No problem with the E7495.
Furthermore, the E7495 is a rugged unit, it's designed and build for use in adverse weather condiitions and with the expectation that it will see at least a certain amount of physical abuse, after which it still has to work 100%. This and considering that these devices are relatively young (I think they started selling the A variant in 2007 and the B in 2009) their reliability and remaining life expectancy is worlds higher than even for the best 85xxA/B Series SA you can find today, and very likely even exceeds many of the current new benchtop devices. It also does that without requiring regular re-adjustment, aside from the internal time base (which just needs GPS lock and is adjusted by the press of a button).
Does the E7495A offer a (1Hz RBW) noise marker function? This is something I would consider essential on a modern analyser for correct analysis of noise signals.
No, it doesn't (but that is something that could be easily done on a PC). But it offers other functionality instead, like a Spectrogram (which shows the frequency band in the time domain with Histogram), measurement of Occupied Bandwidth (OBW) (with user-settable limit), Adjacent Channel Power or Interference Analysis. Especially OBW and Interference Analysis can be pretty useful.
AFAIK the Rigol analysers offer this as a standard feature although I don't know how accurate their system is or if it offers the same noise marker performance/features of the classic lab analysers from the big names.
Quite frankly, from what I've seen from others' and my own Rigol kit, I wouldn't assume that it performs anywhere near the same feature in a big brand SA.
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but on the other side frequency stability is really good (even better than for the 8566B!),
Here we go again...
Frequency accuracy is not the same as frequency stability. A decent lab grade analyser will need to have very good short term stability to preserve its phase noise and also the stability of the trace on narrow spans.
The short term stability of the HP8566B OCXO will be something like +/- 0.001ppm per day and +/- 0.00002ppm over a minute. The stability over seconds and minutes is far more important than the absolute accuracy because it dictates the display trace stability of a lab grade analyser up at many GHz. Your 1ppm E7495A reference won't even come close to this in terms of short term stability even with help from GPS to improve it to +/- 0.03ppm long term.
However, I've just measured the long term OCXO ageing on my HP8566B and also my old HP8568B.
Also note: I don't think the HP8568B instrument has been calibrated for about 10 years. It may be even longer since the OCXO was calibrated as this requires the instrument to be partially dismantled and it is a costly procedure to do it to the formal HP spec.
My HP8566B hasn't had an OCXO recal in several years. I only calibrated the 8566B OCXO back then because I did a minor repair on it just after I bought it that meant I had to take the covers off the RF unit.
Today the HP8566B OCXO measures 9.999 999 95MHz against an offair standard. Pretty impressive! <0.01ppm ageing in several years. It may be that I've measured it at a fortunate time as it will presumably not age in a linear fashion but the result is still very good. Usually the various OCXOs in my sig gens and reference boxes age less than 0.02ppm in many months but these aren't quite in the same class as the OCXO in the 8566.
Today, after maybe a decade since the last calibration the HP8568B OCXO measures 10.000 000 96MHz. But a 1Hz ageing error over a decade isn't bad. I'm not going to bother readjusting either of them as it means taking the covers off the RF unit to get at the adjuster. I'm more concerned about the stability rather than the absolute accuracy.
But my HP8566B OCXO has aged less in several years than your E7495A can manage for short term accuracy even with GPS to help it. The short term stability of the HP8566B OCXO over seconds and minutes will be orders of magnitude better than the one in your E7495A.
I'm assuming that the HP8566B OCXO ageing rate gets markedly less as the OCXO gets older. The ageing spec for the OCXO will be for its early years.
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as are the values for DANL, and sensitivity isn't that bad, either. It's certainly more than just a toy.
It's easy and cheap to throw away dynamic range and get a low DANL. Your analyser will have a preamp fitted.
The difficult bit is getting low DANL and decent SFDR and low input VSWR across the whole range. None of the above matters much for a basic site survey tool so your analyser threw away dynamic range etc in order for it to be able to be sensitive enough to look for small interfering signals arriving at the base station. To stop it overloading from out of band signals Agilent recommend fitting an external high performance and narrow bandpass filter centred at the required base station frequency.
It's a site survey tool... ;)
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Generally dismissing portable units like the E7495 because they don't perform as well as a huge high end lab SA is a bit silly, really.
I'm not dismissing the E7495. For some people it could prove very useful. I'm just challenging what you claim about it each time you paint too much lipstick on it ;)
eg see below:
And quite frankly, if I compare the specs of the HP 8568A and the E7495B then the latter actually looks pretty good compared to the old kit:
And that old SAs like the 8568 have more RF pipework in them is more due to the 30+yrs difference in technology than any performance differences.
but on the other side frequency stability is really good (even better than for the 8566B!)
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It's easy and cheap to throw away dynamic range and get a low DANL. Your analyser will have a preamp fitted.
The difficult bit is getting low DANL and decent SFDR and low input VSWR across the whole range. None of the above matters much for a basic site survey tool so your analyser threw away dynamic range etc in order for it to be able to be sensitive enough to look for small interfering signals arriving at the base station. To stop it overloading from out of band signals Agilent recommend fitting an external high performance and narrow bandpass filter centred at the required base station frequency.
It's a site survey tool... ;)
True. That little LNA I made for looking at phase noise is doing just that. I will do the same when using the scopes to look at low signals. There's no magic.
Generally dismissing portable units like the E7495 because they don't perform as well as a huge high end lab SA is a bit silly, really.
I'm not dismissing the E7495. For some people it could prove very useful. I'm just challenging what you claim about it each time you paint too much lipstick on it ;)
:-DD
Good idea. It does seem to improve the Waveblunder
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::)I'm considering retiring, which I hope will give me some time to do the things I want to do, instead if the things I have to do :clap: One of those 'wants' is to learn a bit about the world above a few hundred MHz (I've managed to avoid RF all my working life), so among other things I will be looking for a SA. Not so much for specific projects, but more for learning about devices, techniques, etc.
Notwithstanding GOHZU's love of his 8568B ;D, I feel that something slightly more recent might be the go. I have looked at many of the different models that have cropped up in the forum discussions, but my RF-uneducated eye could be easily misled. However, it appears that the 8560A/E could get me to a few GHz with fairly good noise performance (I hope, because it is something I will consider important), and for a reasonable ebay price.
I would appreciate comments on this instrument, especially of the 'yes, but...' variety.
Current ebay prices range from $2k - $4k, with one hopeful asking $10k for an 'A' model ::).
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The 8560E is newer, smaller and lighter, performance is not that much better than the venerable 8568B! Close in phase noise is even better on the 8568... plus the UI is vastly better, I have yet find an instrument that is more intuitive than the 8566/8. If I had the space it would be sitting in my lab, but I had to settle for a 8560E.
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Thanks for replying. I've seen a number of posts extolling the virtues of the 8568, and I can certainly relate to the bad vs good implementation of a UI. It sometimes seems like we are going to be plagued with that problem forever. My concern with the 8568 is its age and weight - it would cost a bundle to ship to Oz, then if something breaks it costs another arm-and-a-leg to ship a 'for-parts' unit out here to fix the first one. Hence my casting around for a newer instrument.
..... but I had to settle for a 8560E.
Can I read anything into your choice also of an 8560? Next in line after the 8568? Or did you want some of the features of the E model? Or was it simply because it was available there and then at the right price?
Regards,
Sailor
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As an Oz owner of a venerable 8566B, the 8568's 22Ghz version, I can say I'm glad I bought it!
Yes the freight was stupendous at $700+ to get it here from the US but even with that cost, the total cost of it is still far less than any more modern comparable unit.
These are/were a very popular unit and spare parts abound. That being said they're built like a brick shit house and just keep going. All the manuals, tip notes document etc are available online and if you have some sneaky problem, there is a wealth of information in the hp_agilent_equipment group on Yahoo.
The main problem with these old machines is that the CRTs are wearing out - no problem - colour LCD replacements are available from here...
http://www.simmconnlabs.com/2001/2094.html (http://www.simmconnlabs.com/2001/2094.html)
I hope to add one of those to my unit soon :)
The only thing I would recommend is that whatever unit you buy, get it from one of the reputable dealers who CAL them before shipping, such as this guy I bought mine from...
http://stores.ebay.com.au/AAA-EQUIPMENT-RESOURCES-INC?_rdc=1 (http://stores.ebay.com.au/AAA-EQUIPMENT-RESOURCES-INC?_rdc=1)
No relation - just a satisfied customer.
cheers
Tim
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Just for the record... 8560E is no feather weight either... som 20 kg.
Old age is not going to improve... finding parts will not become easier.
Still if you are lucky and find a pristine 8568B go for it if you have the space.
Love the instrument...
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Thanks for that, Tim. Funnily enough, I had an ebay 8566 page from your guy open at the time I read your post. It may be nice, but it was more than $4k even without shipping etc :-\
I'd still like to hear some quantitative comparison against the 8560 ... or a suggestion of what might be the second cab off the rank after the '66/68.
Sailor
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I got me an Advantest R3361, from ebay for 900€.
Up to 2.6GHz with build in Tracking Generator. (You can Hack the Firmware up to 3.6ghz, with Tracking Generator.)
Full Parts List and Schematics are Available for free.
Menu is Very Nice and Easy to Operate.
But its Ridiculously Big and Heavy.
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@TSL
Tim, I succumbed and bought an 8566B from your mate. I told him how happy you are, offered a figure, and he accepted and organized shipping to Oz for US$400 by FEDEX. He was real easy to deal with, and everything was organized in a few hours. It's a bit (lot!) more than I intended to spend, but it's calibrated, guaranteed, etc etc :)
Now all I have to do is add another 300mm onto the back of my workbench so that I still have some space in front of it to actually do some work!
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Oooh, you'll love your 8566b! The quality just oozes from every part. I had an 8568 (the same instrument but 1.5 GHz limit) and I was deeply impressed with it's incredible RF performance. I had to completely re-arrange my shack to accomodate its bulk, even buying an extra stand for it. It just about fitted. Boy it's heavy, even split up! My Signal Hound SA44b is a wee bit smaller and lighter..... ;D.
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The little signal doggie is doing great! I have spent the whole day doing real money making work and it is a lot easier to use than the Tek RSA6120B that just sits here. I really dislike it.... almost as much as the FSH3 which I NEVER uses, period!
And yes I just had to do a few checks with the 8568 too when I had my doggie shut down for the day, the 8568 boots way faster :D
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Indeed, Mr Simpleton! The DogBox is transformed from an 'also ran' to a real winner with the new SPIKE software. Beats the Rigol into a steaming pulp for phase noise. Everything works and the whole thing is quicker and perkier. Does your SH boot slowly? Mine is up and running in the 6 seconds (actually about 7 seconds) it takes to make the connection, whatever that is. That is surely quicker than the CRT warms up in the HP? ;)
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With boot time I was referring to a shut down PC, which takes 20-30 seconds to start :D Was to lazy unzip the laptop bag, plug all back together and do the quick test. So much simpler just flick a switch and have the 8568 running in matter of seconds! :-+
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Notwithstanding GOHZU's love of his 8568B ;D, I feel that something slightly more recent might be the go. I have looked at many of the different models that have cropped up in the forum discussions, but my RF-uneducated eye could be easily misled. However, it appears that the 8560A/E could get me to a few GHz with fairly good noise performance (I hope, because it is something I will consider important), and for a reasonable ebay price
Thanks for that, Tim. Funnily enough, I had an ebay 8566 page from your guy open at the time I read your post. It may be nice, but it was more than $4k even without shipping etc :-\
I'd still like to hear some quantitative comparison against the 8560 ... or a suggestion of what might be the second cab off the rank after the '66/68.
Sailor
It's a bit late for me to comment on this but for your initial requirements I wouldn't have recommended the 8566 as the ideal choice for you. I'd only really recommend this analyser to someone who 'needed' to be able to have capability across 3GHz to 22GHz with fairly decent performance. This is because of the compromises you have to accept with the HP8566 compared to other analysers that only go to a few GHz.
For example, I'd have taken the HP8560E over the 8566 in a heartbeat if I only wanted to operate up to about 3GHz. Smaller, lighter, MUCH better carrier noise performance, DSP back end for low RBWs (so faster sweeps on narrow spans), better dynamic range and it doesn't make as much fan noise as the 8566. You may be in for a shock when you first power the 8566 up as the fan noise is very loud and can totally dominate a smallish workroom.
But it is a classic piece of engineering and oozes quality whenever it is used. But you may need to get some earmuffs ;D
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Probably the first thing you need to buy for your HP8566 is a decent N Type DC block. There are cheapish ones available that cover 10MHz to 18GHz or 100kHz to 3GHz.
I can't remember what make my N Type DC block is but it covers 100kHz to 18GHz with very low VSWR and through loss so there are decent ones out there that cover nearly the full range of the HP8566B.
Without this DC block you can easily fry the front end of the 8566 if you accidentally feed a DC voltage to it. It is only rated to 0V DC and can be (expensively) damaged by just one accidental feed of a DC voltage of just a few volts. Especially if you select 0dB attenuation inside the analyser as there is a diode limiter in the 2.5GHz range that can be fried with a very low DC voltage.
At my place of work, more people damaged their analysers with DC than with RF overload so be very careful with that HP8566 !
I'd recommend you make or buy an RF limiter for it as well. Especially if you aren't very RF savvy yet :)
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@Sailor
Glad you had a good experience with the guy, same as mine. $400 FEDEX is a bargain - I bought mine a few years ago and shipping was north of 700 then.
I hope you like the beast, and yes it has a loud fan as does most HP kit from that era. I have a HP54720A DSO and an ancient HP 8660C sign gen that compete with the 8566B for loudest fan. I think the 8660C wins!
I've also bought the 11970K external mixer for my 8566B to extend its operation to 26Ghz since I have some work to do at 24Ghz. The external mixers can cost a bomb but if you're prepared to wait a while you can pick them up for a good price.
Get yourself a PCI GPIB card or for USB a Prologix USB to GPIB converter and then go get the GPIB Toolkit from here...
http://www.ke5fx.com/gpib/readme.htm (http://www.ke5fx.com/gpib/readme.htm)
This will allow you to capture your traces direct to your PC and there's other cool things such as, this...
"IMD_8566B_8568B.BAT uses TALK.EXE to transmit the downloadable program (DLP) T_HIRDIMOD to the nonvolatile user RAM on an HP 8566B or 8568B spectrum analyzer. This program performs basic third-order intermodulation distortion measurements on signals between 10 MHz and 500 MHz, and also calculates IP3. See HP product note 8566B/8568B-1 for more information. "
There is a couple of other add on programs to download to it too.
regards
Tim
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Probably the first thing you need to buy for your HP8566 is a decent N Type DC block. There are cheapish ones available that cover 10MHz to 18GHz or 100kHz to 3GHz.
[snip]
I'd recommend you make or buy an RF limiter for it as well. Especially if you aren't very RF savvy yet :)
What he said !! :-+
I have a DC block plugged in all the time, you only need one faulty circuit to put DC on the input and poof!! there goes your front end. :scared:
I also have a selection of attenuators from 3 to 40dB that go inline if I suspect something is going to output a sig higher than expected. I also have a a handful of directional bridges with various dB coupling so the SA can be outside the signal path where needs be. Mostly when testing amplifiers above 100watts.
Don't be tempted to hook up an external reference to it either, the internal ref has exceptionally low noise figure and it would take an extremely good external reference to beat it.
regards
Tim
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The HP8566 is also a bit prone to developing minor niggly issues with the YIG/Control and at some point it may start throwing up onscreen BITE errors like YTO Unlock and also one or both of the little red STATUS LEDs may wink on or off intermittently after the initial bootup sequence. These LEDs usually indicate that a self test error has occured.
Usually this isn't serious and can be traced to a few dried out electrolytic capacitors in the RF unit. The HP8566B is quite easy to work on so the YTO Unlock fault could potentially be fixed in a couple of hours assuming you check lots of caps with an 'in circuit' ESR meter.
It's also worth checking it can pass its own internal error compensation program. This is a short calibration/correction routine that attempts to improve the factory calibration by measuring and compensating for ageing effects in the analyser RBW filters etc. You loop back the 100MHz cal signal to the RF input and then start the automated routine by pressing [SHIFT] [FREQUENCY SPAN]. It takes about 1 minute to run.
Once it has completed the CRT will show a little 'Corrd' logo onscreen.
However, it will disappear if you hit PRESET or reboot the analyser.
You can recall this calibration (without rerunning it) after every reboot by pressing [SHIFT] [START FREQ].
or you can set it back to factory default with [SHIFT] [STOP FREQ]
It is definitely worth running this cal routine after the analyser is fully warmed up as it will improve the calibration across all the RBW settings compared to the factory default setting.
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@ everyone
Thanks for all the notes, and please, if any other odd bits of advice come to mind later, you could always just PM me. Good stuff like this comes from (hard) experience, not out of a manual.
I've been looking at the ke5fx site for three or four days now, lots of goodies there. I was going to ask about GPIB interfaces - I have several machines with ISA, PCI, or, of course, USB that I could use. I've got w2k, XP, and W7, so the question is - is it easier/harder/better with any of those systems? I vaguely remember reading of people having problems with some USB implementations, but I didn't take much notice at the time. Is there anything special about making a GPIB cable? Length, shielding, etc?
A DC block, and some form of limiting have been weighing on my mind for a while. I've always been paranoid about double-checking before turning on anything with significant powers involved, but this 0V DC and mWatts-max is going to be a whole new ballgame for me. Tim has a block installed permanently - I'll follow suit, but with some added measure to deter me from removing it inadvertently, like when my brain is five minutes ahead of my hands :P
BTW, whats with some of those Chinese devices - DC blocking (200V), but freq resp DC - xxGHz :-DD
Does the 8566 power-up with a default attenuator setting, or with the last-used setting?
... I also have a a handful of directional bridges with various dB coupling so the SA can be outside the signal path where needs be.
That sounds like a good idea.
That's good info about bad caps GOHZU. Last night I fed in 8566 to the search on the yahoo Agilent group, and was overwhelmed by the number of messages. I obviously couldn't even read a fraction of them, but I did notice that similar comments came up there also. I just hope I don't need to dive into this machine for a year or two. Much as I love exploring anything new, I know that I'm at the bottom of a steep learning curve right now, and I'd rather not run the risk of stuffing up something. Analogue, digital, power, I have no problem with, but I just know that I'm going to get caught out here more than once or twice...
Regarding the fan noise, has anyone looked at using different fans? I can remember some fan noise problems in the late '70s - '80s being mitigated somewhat with redesigned blades. I can understand the display generating a lot of heat, but the RF section?
Thanks again to everyone :-+
Sailor
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If I recall correctly the 8566 do have 10 dB attenuator switched in at start up and reference level is at 0 dBm (top of screen).
Assume it behaves like the 8568 which you cannot step the atteunuator to 0 dB, you have to punch in the digits. I see this as a safety measures.. :D
I am using a USB-HP/IB from National Instruments works like a charm with KE5FX programs. Have tested this with both 8560E and 8568B.
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I am currently looking for an SA, mainly for EMC precompliance tests. The Rigol DS815(-TG) would most likely just be fine, but even if 1200 EUR is a bargain, it is a lot of money for a device which I will use only a couple of times a year.
I have been eying eBay for a while (and reading this thread, of course). Over here in Germany, the supply of used test gear is a lot worse than in the US, but considering shipping and tax, buying in the US does not make much sense.
There is currently an Advantest TR4131 on sale. According to my web research this is a late 80s device, 9kHz...3GHz, rather bulky and heavy, with some issues regarding frequency stability. For EMC, I feel this should not be too big an issue (but I am not an expert, EMC is just something I can´t avoid). The unit in question has had its last calibration around 2002.
Does anyone know the device and can give me an idea how much this would be worth? The seller claims that the unit is in good state, I would have to rely on the self-test. Or would the unit make little sense for EMC testing?
Max
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Regarding the fan noise, has anyone looked at using different fans? I can remember some fan noise problems in the late '70s - '80s being mitigated somewhat with redesigned blades. I can understand the display generating a lot of heat, but the RF section?
It may be possible to change the fans to an intelligent system where they only operate at speeds required for a certain temperature inside. Eg change the fan type and also use a cheap AFVR/PIC MCU and temp sensor and fan controller circuit. It might mean that the overall measurement uncertainty of the instrument degrades slightly (over time) but I think it would be worth it for many users.
On the HP8566 the fans come on full blast from cold and make an awful lot of noise. These analysers are tolerable in a large open plan work lab because there are other sources of noise and the noise will travel across the lab. But in a typical hobby room/shack/shed the fan noise will dominate the room and will be difficult to live with unless the operator is insensitive to loud fan noise or there are other fan noises that are already as bad (unlikely!)
I can understand the display generating a lot of heat, but the RF section?
ermmm... have you seen the size of the fan on the 8566 RF section? It's a monster. Mine has a huge cover/filter on it and I think this is typical. I've not tried to see where the bulk of the noise comes from but my 8566 is definitely a bit louder than the 8568 so I assume the huge fan on the RF section on the 8566 is the reason.
I took a quick picture of the back of my 8566. See below. You can see the size of the RF fan (arrowed). Whilst it would be an exaggeration to say it sounds like an F16 fighter jet when it starts up, it does make a lot of fan noise especially if you operate it in a small room near a backwall.
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So why does a high performance spec ana create so much heat?
One of the keys is dynamic range, so a cheap spec ana will be running level 13 mixers, so +13dBm as the LO drive level. The higher the level of mixer the higher the third order intercept point and the lower the spurious products. A lab grade analyzer will be running level 23 or 27 mixers, and the amplifiers driving those are dissipating at least a watt. The amplifiers in each IF stage will also need to be running at that level, so you end up with everything running far more power than on an economy unit. The 1st LO amp has to cover a wide frequency range, approaching an octave and you can't run it at the most optimum efficiency match so you've usually got several watts of heat being dissipated just from that one amplifier.
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My take is that the logic is the main culprit of heat! This instrument was designed in late 70's early 80's and is probably chock-full with ECL and other power hungry semiconductors... Plus owens for ref oscillator and YIG... A few mW amps/mixers would hardy be noticed :-/O
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I think a lot has to do with the sheer complexity of the thing.
The swept LO system is a very complicated system with lots of active devices in it. Presumably all of this has to be carried out at a highish RF power level at each stage to keep the performance high and the noise levels low.
Then there's the signal path including the YIG filter and there's also the A15 controller unit. It all adds up. However, I just tried measuring both the Display and the RF unit for power consumption and it was lower than I expected!
My 8566 is an AB version that started out as an A but was converted to B with a factory upgrade. Also note that I only have a cheap and cheerful inline meter for this so it isn't going to be very meaningful/accurate...
I measured the RF unit from cold and also when the OCXO was warmed up:
HP8566AB
RF Unit:
Standby Cold: 24W (OCXO cold)
Standby Warm: 12W (OCXO warm)
Initial Power Up: 195W High band
Initial Power Up: 190W Low band
Warmed Up Power: 190W High band (measures 244VA in VA mode)
Warmed Up Power: 186W Low band (Measures 240VA in VA mode)
Display Unit:
Standby: 4W
Running: 138W (Measures 168VA in VA mode)
Combined RF + Display Unit:
Standby: Warm = 16W
Running: = 328W (Measures 404VA in VA mode)
I also experimented by placing my hand over each fan to baffle it and (surprisingly) the display unit fan noise is more annoying than the fan noise from the RF unit. But there's not much in it.
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I've been looking at the ke5fx site for three or four days now, lots of goodies there. I was going to ask about GPIB interfaces - I have several machines with ISA, PCI, or, of course, USB that I could use. I've got w2k, XP, and W7, so the question is - is it easier/harder/better with any of those systems? I vaguely remember reading of people having problems with some USB implementations, but I didn't take much notice at the time. Is there anything special about making a GPIB cable? Length, shielding, etc?
I use a National instruments PCI GPIB card in my Win7 PC. That works just fine with no issues. I also have an Agilent USB-GPIB adapter 82357B, plugged into my HP53181A frequency counter. I specifically bought the USB adapter for use with a Microsoft Excel plugin from Agilent that takes the counter output and dumps it straight into Excel. Great for measuring freq drift over time. The plugin would not work with my NI card :(
You can get clones of the Agilent USB-GPIB adaters,
http://www.ebay.com/itm/82357B-GPIB-USB-Interface-Compatible-with-AGILENT-82357B-/25164199097 (http://www.ebay.com/itm/82357B-GPIB-USB-Interface-Compatible-with-AGILENT-82357B-/25164199097)
I bought that one and it works just fine. If you want the genuine article keep an eye on eBay as they pop up for reasonable prices often.(not often enough when I wanted one)
BTW, whats with some of those Chinese devices - DC blocking (200V), but freq resp DC - xxGHz :-DD
Not sure what you mean here, but having a high voltage breakdown is good for working on RF stuff especially if you work in the lower frequencies. i.e. I'm working on a transmitter for MF about 475kHz. The antenna matching coil is around 1mH, and even thought the transmitter is powered by 12v and outputs only 10w, the resultant RF voltage on the top of the coil is around 1800v! :scared:
Needless to say I'm using a directional coupler to sample the RF :)
Likewise if you ever have to work on valve based RF amps, working voltages are often 200v to 4kv DC. Plenty of places to come unstuck if your not paying attention.
regards
Tim
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Hewlett Packard Journal article about the 8566 from 1979.
http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1979-08.pdf (http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1979-08.pdf)
Keysight UXA is spec'ed with a 25W standby and 850Watt Max. Net weight spec'ed at 68 pounds.
http://literature.cdn.keysight.com/litweb/pdf/5992-0090EN.pdf (http://literature.cdn.keysight.com/litweb/pdf/5992-0090EN.pdf)
Bernice
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I think Sailor is asking how a DC block can have a response from DC - (name any frequency). :-//
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If anyone is interested in the power consumption of the HP8568B and the Advantest TR4172 I measured them both today here in the UK (230V AC typical).
HP8568B
RF Unit:
Standby Cold: 24W (OCXO cold)
Standby Warm: 12W (OCXO warm)
Warmed Up Power: 104W (measures 131VA in VA mode)
Display Unit:
Standby: 4W
Running: 136W (Measures 164VA in VA mode)
HP8568B Combined RF + Display Unit:
Running: = 244W (Measures 300VA in VA mode)
I also measured the complete TR4172
TR4172 Combined RF + Display Unit:
Standby (warm) 6W
Running 247W (304VA in VA mode)
Note: It briefly takes about 270W at startup but falls to 247W in a few seconds.
According to the Advantest service manual it takes 'approx' 300VA and my meter appears to agree with this very well.
I'm not sure why my HP8566 and 8568 take much less than their HP datasheets says but maybe HP quote the worst case peak under the worst case line voltage and ambient temperature?
I looked up the specs for my cheapo inline meter and it claims to be within 1% accuracy for Watts and VA which seems a bit hard to believe...
However, the HP8568B and the TR4172 have the same measured W and VA according to my meter. Nothing in it!
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So according to my cheapo meter, the HP8566 RF unit is 190W vs 104W for the HP8568B RF unit. Which probably explains the big power bulge box in the back of the HP8566 RF unit that houses its huge cooling fan :)
"We're going to need a bigger boat fan...."
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Anyone ever use one of these?
http://www.tequipment.net/assets/1/26/Documents/Protek/7700.pdf (http://www.tequipment.net/assets/1/26/Documents/Protek/7700.pdf)
Any chance one of these could be worth $300?