RF Signal Generator w/ Sweep for ham radio projects

[cio74]

Hello,

I could use some help, I'm looking for a RF signal generator that should help me with hobby HF ham radio related projects (RF filters, mixers, pretty much anything related to building a transceiver).

I have been looking on Ebay over the last week, there are a few I like but some of them have rear connectors, that will be very inconvenient for my setup. In the end I am drawn towards an Anritsu MG3633A found on Ebay that I can get for about £600, front connectors, weighing, eh, 60+ lbs. They seem to be built around 2001-2003, question is, are they still good after nearly 15 years and would they still work over the next few years?

Thanks.

Cio

[acbern]

Anritsu is good value, everybody wants agilent/keysight, you can get that item even cheaper i would think if you look arround.
Disadvantage: no service manuals with schematics usually and no special repair parts. But on the other hand, these are hard to repair anyway, and the price is low enough to give it a shot.

[cio74]

Thanks, are they built that good to survive a couple more years, altho not expensive at £600 I would definitely want to use it for at least another 5 years...

[acbern]

There is no global answer for this. Vice versa, if you spend say 800 for an agilent, you cannot be sure it will work longer. You can sell it easier, thats for sure.

[cio74]

Yes, of course, that's all well known.

It is a bit of gambling buying 10+ years old equipment and hope to see it running for few more years. Some would say the price should be low considering there is no warranty of what so ever that the equipment will last for 1 month not 1 year but the reality is different. I think I have seen a few with 1 year warranty but the majority are sold 'as is'


Would I be better off buying some HP instead, perhaps easier to repair or re-sell compared to an Anritsu or Rohde&Schwarz?

[uncle_bob]

Hi

The biggest drawback of most modern "sweep" generators is the fact that they can sweep amplitude. In most cases this was done with mechanical relay based attenuators. The relays have a rated life of a few million operations. You can easily come up with a sweep pattern that takes the relays past end of life in under a month. I've done this on a couple of generators. Fortunately it was a "test we must do / charge the customer" sort of thing. Hint: Don't do 24 hour a day 7 day a week amplitude sweeps unless somebody is paying you to to it ...

Provided it comes with some sort of warranty, I would not worry about it. Either they work fine when you get it or they don't. If it does not come with a warranty *AND* if Anritsu used the relay approach on this generator, you have some element of risk.

Bob

[PA0PBZ]

Since nobody asked yet: What frequency span are you looking for, what accuracy and what is it you want to sweep, just frequency?
There are still some analog sweeping RF generators out there...

[nctnico]

Would I be better off buying some HP instead, perhaps easier to repair or re-sell compared to an Anritsu or Rohde&Schwarz?

HP easier to repair? I don't think so. Service manuals for more modern HP gear describe at the block diagram level and go no further into details than required to swap a module.

[DimitriP]

You can always go analog and use the extra pounds for extra pints or parts ....

http://www.ebay.co.uk/itm/SIGNAL-GENERATOR-/182161005933?hash=item2a69a45d6d:g:Q~QAAOSwbYZXVTYy

[uncle_bob]

Would I be better off buying some HP instead, perhaps easier to repair or re-sell compared to an Anritsu or Rohde&Schwarz?

HP easier to repair? I don't think so. Service manuals for more modern HP gear describe at the block diagram level and go no further into details than required to swap a module.

Hi

Easier to repair because you *may* be able to find a board to swap out. Good luck finding a source of "donor parts" for some of the other brands.

Bob

[cio74]

Since nobody asked yet: What frequency span are you looking for, what accuracy and what is it you want to sweep, just frequency?
There are still some analog sweeping RF generators out there...

0.5-100MHz is more than enough, looking to get an unit I trust, in my view the biggest issue if you don't know if your signal is bad or the measurement is bad, therefore looking for an accurate generator. And yes, frequency sweep is what I have in mind to use. You have a ham radio callsign, think of an instrument useful to help you build various ham related projects, inject signal for pre-amps, mixers, IF alignment, bandpass filters response and so on.

I do like that Anritsu just a little worried since it comes with zero warranty. actually they will replace it if it's defective so no DOA but that's pretty much all warranty I get.

[Wuerstchenhund]

I have been looking on Ebay over the last week, there are a few I like but some of them have rear connectors, that will be very inconvenient for my setup. In the end I am drawn towards an Anritsu MG3633A found on Ebay that I can get for about £600, front connectors, weighing, eh, 60+ lbs. They seem to be built around 2001-2003, question is, are they still good after nearly 15 years and would they still work over the next few years?

Yes, assuming they have been treated well. But don't forget that Anritu's main customers are cell phone companies, who use such generators for automatic test systems, which will affect the remaining life of the mechanical RF attenuators (which have a limited service life). Newer generators often have the option of an electronic attenuator, which is more durable.

Also, the MG3633A is closer the 1996 - 2000 era, and I'd check the condition of the device very thoroughly before buying. Anritsu gear is generally very robust, and the build quality is very high, but getting parts can be very difficult (don't bother contacting Anritsu as individual, they're pretty much only responsive to businesses, and even a business dealing with Anritsu can be a challenge).

[acbern]

Cio74, i dont know how it is in the uk, but in germany if you buy used gear as an end user (not company) from a company, they have to give you a warranty. Insane imo, but thats how it is.

[HighVoltage]

I have both, an R&S SML-1  and an HP RF sweep generator. Both were bought dead and repaired by me. I was lucky because the repair was not too complicated. I would highly recommend one of these brands, because there are lots of people here on eevblog that can help with them and you can get reasonable prices if you have a little time and watch the market.
My HP generator is the 8648C similar to the one Shahriar repaired in this video episode
http://thesignalpath.com/blogs/2012/10/07/teardown-and-repair-of-an-hp-8648c-synthesized-signal-generator/

[HighVoltage]

Here is one popping up right now:
http://www.ebay.de/itm/HP-Agilent-8647A-250-kHz-1000-MHz-Signal-Generator-/262478648458?hash=item3d1cf2548a:g:HMAAAOSwvg9XWyGc


(I have nothing to do with this listing)

[cio74]

Thanks, it does not have sweep function.

I'll keep an eye on Ebay maybe something good pops up.

[uncle_bob]

Thanks, it does not have sweep function.

I'll keep an eye on Ebay maybe something good pops up.

Hi

It does have a GPIB interface, so getting it to sweep is pretty easy.

Bob

[cio74]

Thanks, it does not have sweep function.

I'll keep an eye on Ebay maybe something good pops up.

Hi

It does have a GPIB interface, so getting it to sweep is pretty easy.

Bob

Thanks for the tip, I'm not familiar with that communication interface, I assume to sweep I will need a PC to send commands. That's doable, I shall read more about how to do that.

[uncle_bob]

Thanks for the tip, I'm not familiar with that communication interface, I assume to sweep I will need a PC to send commands. That's doable, I shall read more about how to do that.

Hi

Quick run down:

GPIB (also known as HPIB on HP gear) is a standard way to run test gear. A lot of instruments have the magic connector on the back. A variety of people make adapters that either plug into a PC or a USB port. There are a few Ethernet based and serial based devices as well. The USB version is probably your best bet.

Since it's a common interface, there are oceans of code out there to deal with it. There are even software empires (LabView) built more or less around it and other common interfaces. If you have modern gear, it is worth investigating.

Bob

[Howardlong]

Since nobody asked yet: What frequency span are you looking for, what accuracy and what is it you want to sweep, just frequency?
There are still some analog sweeping RF generators out there...

0.5-100MHz is more than enough, looking to get an unit I trust, in my view the biggest issue if you don't know if your signal is bad or the measurement is bad, therefore looking for an accurate generator. And yes, frequency sweep is what I have in mind to use. You have a ham radio callsign, think of an instrument useful to help you build various ham related projects, inject signal for pre-amps, mixers, IF alignment, bandpass filters response and so on.

I do like that Anritsu just a little worried since it comes with zero warranty. actually they will replace it if it's defective so no DOA but that's pretty much all warranty I get.

How about HP/Agilent 8935 E8380A or E6381A? These test sets also include receiver sensitivity tests as well as sweep gen and spec an for sweeping filters if that's what floats your boat. Add an external return loss bridge and it'll do scalar network analysis. General coverage is from 0.4 to 1000MHz, plus a bit of L band for cellular applications. They go for about £500 on eBay.

[Neganur]

The dwell time (switching time) on the 8648X is pretty limiting when you want to sweep a frequency range in my opinion. It's around 100ms per point.
The R&S one is a bit better with 10ms so I would rather recommend this unit.

of course both will sweep but if you do a 1MHz step on a 1GHz range you can go fetch a coffee. Perhaps taking an VCO IC is a better solution if you want a faster sweep.

[uncle_bob]

Since nobody asked yet: What frequency span are you looking for, what accuracy and what is it you want to sweep, just frequency?
There are still some analog sweeping RF generators out there...

0.5-100MHz is more than enough, looking to get an unit I trust, in my view the biggest issue if you don't know if your signal is bad or the measurement is bad, therefore looking for an accurate generator. And yes, frequency sweep is what I have in mind to use. You have a ham radio callsign, think of an instrument useful to help you build various ham related projects, inject signal for pre-amps, mixers, IF alignment, bandpass filters response and so on.

I do like that Anritsu just a little worried since it comes with zero warranty. actually they will replace it if it's defective so no DOA but that's pretty much all warranty I get.

How about HP/Agilent 8935 E8380A or E6381A? These test sets also include receiver sensitivity tests as well as sweep gen and spec an for sweeping filters if that's what floats your boat. Add an external return loss bridge and it'll do scalar network analysis. General coverage is from 0.4 to 1000MHz, plus a bit of L band for cellular applications. They go for about £500 on eBay.

Hi

One thing to be careful of on the various "cell phone test sets":

The hardware is broadband in most of them and quite capable of < 1 MHz to >= 1 GHz coverage. They may or may not have been calibrated over that entire range. They may or may not have the full range enabled by default. It's always a good idea to do a bit of research on the specific unit you are bidding on to be sure it has what you are after. Turning a "limited" one into a "full" one apparently is a doable thing. You need a fairly well equipped shop to get the job done. The conversion and calibration is not a quick basement project sort of thing.

All that said, I have one, they do a really good job.

Bob

[G0HZU]

If you just want a reasonable sig gen for HF use then I'd recommend the little Marconi 2022 if you can find a tidy/healthy one. The phase noise is fairly good on the HF bands but not in the same class as the best generators on the HF bands. But for general ham radio stuff this is a good little sig gen. it isn't going to be much use as a sweeper though. If it has the GPIB option you could sweep it slowly over GPIB with a PC but I don't recommend this as a long term solution for sweeping.

If you want to sweep stuff down here then why not build a simple DDS board and drive it with a decent MCU chip? You should be able to sweep it quite fast from LF through the HF bands. If you need to go 'very' fast on the sweep then go for one of the DDS chips that can sweep itself according to your programmed limits.

However, I'm not sure why you want (as in 'need') a sweeper for ham radio stuff. The little Marconi 2015 and 2016 has a sweep/ramp input allowing it to be swept with a function generator within its sub ranges but the sub ranges are fairly limited in range. The primary function of the sweep input is to allow the connection of the synch unit to phase lock it but you can use it as a sweeper with a function generator/ramp waveform.

[uncle_bob]

However, I'm not sure why you want (as in 'need') a sweeper for ham radio stuff.

Hi

I also am a bit puzzled by that. Without some sort of tracking detector, there isn't a lot you can do with a sweeper. To get a good tracking detector, you buy a spectrum analyzer with a tracking generator or a network analyzer instead.

Bob

[vk6zgo]

However, I'm not sure why you want (as in 'need') a sweeper for ham radio stuff.

Hi

I also am a bit puzzled by that. Without some sort of tracking detector, there isn't a lot you can do with a sweeper. To get a good tracking detector, you buy a spectrum analyzer with a tracking generator or a network analyzer instead.

Bob

An RF sweeper with a sweep rate sawtooth available to use as a H input on an Oscilloscope,a detector,& you have a device which can show you the amplitude/frequency response of a circuit.
A little more messing around,& you can look at input impedances of circuits,antenna feeders,etc.

It is,in effect a Scalar Network Analyser,
Back in the day,when I worked at a place doing TV Transmitter maintenance,if the Polyskops were all out,we would use a Wavetek  RF sweeper & a detector,instead.

None of this stuff,including a Polyskop,is as good as a VNA,but very useful work can be done with them,nevertheless.