HP 8592B spectrum analyzer

[taydin]

Guys, I have found an HP 8592B spectrum analyzer that the owner is willing to give for $400. He says it's working, but when I asked a little more, he said, well last time I turned in on, it did spontaneously turn itself off after a while. So it might need repair, but a 9 KHz to 22 GHz spectrum analyzer for $400, even needing repair, sounds like a good deal ... What do people here think?

The reason I want this is to educate myself in RF technology. The upper limit of what I will be dealing with is probably 6 GHz, which covers the 802.11ac band. I don't see myself ever dealing with higher frequencies.

I have seen Shariar at "The Signal Path" review the HP 8562B, which seems to be a model with certain quirks, but looking at the user's manual of both, the only difference I noticed is that 8592B seems to have programming capability through RS232 and a proprietary HP IB interface.

Any feedback welcome!

[Bicurico]

I will buy it for US$450.
There will be others here increasing my offer, for sure.
So yes, you are sitting on a great deal.
But that doesn't mean this is a useful device for you.  It depends if you like to learn how it works and repair or maintain it.
Regards,
Vitor

[taydin]

Thanks for the response!

The first project I'm looking forward to use this SA in building the hackrf or the limeSDR from scratch. I will also buy a 15 GHz signal generator that a local company is manufacturing. It has impressive specs and only costs $749. So, an SDR build that covers the 802.11ac band, which means 6 GHz. But having 22 GHz bandwidth, I would also be able to see any harmonics of this 6 GHz

I don't think I will be able to buy a 6 GHz probe anytime soon, so initially my usage of these units will be mostly checking the presence of a signal or the lack thereof.

[hendorog]

I have seen Shariar at "The Signal Path" review the HP 8562B, which seems to be a model with certain quirks, but looking at the user's manual of both, the only difference I noticed is that 8592B seems to have programming capability through RS232 and a proprietary HP IB interface.

Any feedback welcome!

The 856x series have a significantly better RF spec than the 859x series. They are also more expensive naturally. I haven't used either of them though.

What you have sounds like a good deal to me. If you get to the point where you need something better than you are likely to be able to get your money back.

[tggzzz]

So it might need repair, but a 9 KHz to 22 GHz spectrum analyzer for $400, even needing repair, sounds like a good deal ... What do people here think?

The reason I want this is to educate myself in RF technology.

Lucky you!

Be aware that RF front ends are often very sensitive and relatively unprotected: DC bias and overload can be a problem. Even measuring some mixers' diodes with some multimeters might cause problems, so approach with caution. Ditto ESD.

A generic failure point is PSU capacitors, so the first check should be to ensure every PSU rail is within spec for voltage and ripple.

[taydin]

So it might need repair, but a 9 KHz to 22 GHz spectrum analyzer for $400, even needing repair, sounds like a good deal ... What do people here think?

The reason I want this is to educate myself in RF technology.

Lucky you!

Be aware that RF front ends are often very sensitive and relatively unprotected: DC bias and overload can be a problem. Even measuring some mixers' diodes with some multimeters might cause problems, so approach with caution. Ditto ESD.

A generic failure point is PSU capacitors, so the first check should be to ensure every PSU rail is within spec for voltage and ripple.

Thanks! Yes, I noticed in the specs, it says "maximum DC = 0"

If any DC is killing this thing, why didn't HP put some kind of DC block? Maybe because it's already hard to get a reasonably flat frequency response for 9 KHz - 22 GHz, the addition of a DC block would make this much harder?

[cncjerry]

DC block raises the input minimum frequency.  Also, it probably shut off due to a power supply cap.  Price seems good for the model.

[ps]

Guys, I have found an HP 8592B spectrum analyzer that the owner is willing to give for $400. He says it's working, but when I asked a little more, he said, well last time I turned in on, it did spontaneously turn itself off after a while.

I has the same issue with a HP8591A. It worked fine for a while and then suddenly restarted or turned off. Checking the voltages revealed a weak 5.2 V supply that started to drop after a while until undervoltage reset was triggered.

Root cause was a leaking capacitor. Spilled electrolyte has flown into the voltage reference circuit located below this capacitor. This shifted some resistance values at higher temperatures, causing the output voltage to drop. After cooling down everything was fine again.

Replacing the capacitor and cleaning the board fixed that issue.


$400 is an excellent price for an 8592B. Even an 8590A (1.8 MHz without counter lock) is more expensive.


Patrick

[taydin]

Ok I finally met with the seller and bought the spectrum analyzer. He said he also had other equipment, so we looked at the attic. I saw the 18 GHz frequency counter there, which had a warning sticker on it saying that the 500 MHz - 18 GHz range isn't working But I still took it. Paid about $900 for both the spectrum analyzer and the counter. They sure look quite beat up, so cleaning will be the first step.

[taydin]

Tested the frequency counter, and just like the label says, only the 10 Hz - 500 MHz range is working. But it seems the fan on this thing is still the original fan, and it sounds like a motorcycle

[taydin]

Tested the spectrum analyzer. It doesn't turn on at all. No activity whatsoever, no lights, no sound. Checked the mains fuse, it's good. Checked the mains voltage setting, it 230V, no problem there either. So this seems to be a power supply issue. I hope it's the only issue. When looking at the front side, I saw that some RF components are kinda rusty. Hopefully they are in good condition, would be hard finding those if I had to replace them.

[taydin]

I have removed the power suppy, opened it up and did a general examination. Right away, I noticed that the main bridge rectifier was blown. I replaced it, put it back together and applied power again. The unit turned on, but the screen only had a few horizontal scan lines and after a while, turned itself off.

I opened up the power supply again and replaced all electrolytics inside. two of them were definitely leaky. After that, applied power again. This time, the unit turned on and the screen showed some sensible information, but it soon turned itself off again. So something else is going on besides the leaky caps.

[taydin]

To see if there are issues other than the power supply, I removed the connector of the unit's own SMPS, set up two lab power supplies and applied all voltages that were needed. -15V, +15V, +12V, and +5.2V. Now the unit did turn on and the screen showed sensible information.

[taydin]

This SA has an N type input and my signal generator has a BNC type output, and I don't have a cable to connect the two, so I wasn't able to confirm that the SA itself is working properly.

But I had an N-type to SMA converter, so I used that with a 2.4 GHz antenna. I then set the center frequency to 2.4 GHz and the span to 500 MHz. But the spectrum doesn't show anything sensible. So it looks like there are other problems with the unit itself. I tried running the frequency cal and the amplitude cal, but they all failed saying that cal was not found. I looked at the cal output using my scope. It has a 300 MHz output.

I guess I have to read up on the manual ... As far as I know, the unit should source the calibration signal internally, and I shouldn't need to connect cal out to the SA input. But I'm not sure.

[Bicurico]

Hi,

I thought that the SA was in working condition...

Anyway, from my recent experience with a Keysight E4403B (=Agilent, =HP -> just more recent than yours), it does self-calibrate.

I am not literate in telling you what could be wrong, but you should probably start by cleaning the boards and replacing aged electrolytic capacitors.

Beware of the YIG, as it contains Yitrium. Not here to scare you, but to save you from scaring yourself, like it happend with me with Berylium Oxide inside a R&S CRTU...

Good luck!

Regards,
Vitor

[taydin]

Just checked the manual. To do any cal, it is necessary to connect a cable from CAL OUT to the input. So I need to get an N-type to BNC adapter and a short 50 Ohm coaxial cable.

[Bicurico]

for quick and dirty test, you could just connect a wire directly from N to BNC. Carefu,l though, to not break the connector.

[taydin]

Hi,

I thought that the SA was in working condition...

Anyway, from my recent experience with a Keysight E4403B (=Agilent, =HP -> just more recent than yours), it does self-calibrate.

I am not literate in telling you what could be wrong, but you should probably start by cleaning the boards and replacing aged electrolytic capacitors.

Beware of the YIG, as it contains Yitrium. Not here to scare you, but to save you from scaring yourself, like it happend with me with Berylium Oxide inside a R&S CRTU...

Good luck!

Regards,
Vitor

Thanks for the tips! I think I will be able to fix the power supply. Worst case, I can just empty out the PS enclosure and build an alternate power supply with the required voltages. But not sure what's going to happen with any other problems. This unit might end up being expensive to repair, but I will still try to repair it. If nothing else, the education I'll get will be worth it

[ps]

Did you wash the PSU boards after replacing the electrolytics? That stuff conducts, the warmer the better.

[taydin]

I cleaned it with isopropyl alcohol, so the area where the leaky caps were should be clean. Also cleaned the PCB where I replaced caps, even if they weren't leaky. I also cleaned other parts using cotton balls dipped in alcohol. But it wasn't an exhaustive cleaning covering every area.

[collett.marcelo@gmail.com]

Guys,
Recently I bought a defective HP8592B spectrum analyzer on ebay and after some tests I came out to some conclusions and doubts .....

The analyzer input is not responding to the input signals and the calibration procedure generates the "REF Signal not found" alarm.

I noticed that the YIG is not generating any RF signal on the SMA connector ....
The 5V and 15V supply voltages are present, but I am suspecting about some points  regarding the maincoil control signal.
 
Pin1 = -15v
pin2 = gnd
pin3 = gnd
pin4 = + 5v
pin5 = maincoil + = + 14.8v
pin6 = maincoil- = + 10.3v
pin7 = gnd
pin8 = + 14.8v
pin9 = FM-signal = 0.04v
pin10 = FM + signal = 0.04v

I also mesured the main coil current at these conditions:
(zero span and center frequency at 1 Mhz) - 72mA
(zero span and center frequency at 2.9Ghz) - 153mA

With this information I believe I can conclude that YIG is faulty, but my question is about the driver card ?
Could someone help me with the information if is correct for the main coil control current change only from 72mA to 153mA to cover the full range from 3Ghz to 6.8Ghz of this YIG ?

Thanks ! 

[Stray Electron]

Be aware that RF front ends are often very sensitive and relatively unprotected: DC bias and overload can be a problem. Even measuring some mixers' diodes with some multimeters might cause problems, so approach with caution. Ditto ESD.

   I know that this is already too late in this case but FYI in my experience, 90% of the used SAs out there have blown front ends.  Unless I can see one work and see that it is reading the input, I won't more than a scrap price for a used SA.

   The other thing that I always check before buying any high end test equipment is whether there are REAL service manuals available. Not the board level replacement nonsense but down-to-the-component level schematics, parts list, etc. Otherwise you could just be looking at an expensive boat anchor.

[collett.marcelo@gmail.com]

 
You are right on your consideration and I am just afraid my unit is one of these cases because I could not found any service manual with component level schematic's !!! 

In my case I think the front end is not blown, once i could see some signal on the display when I applied a 3,6Ghz to 7Ghz from my generator to the mixer, doing the YIG function..... of coarse the frequency is not correct but is only to test the signal is going thru the next stages....

So, I really appreciate if someone could help me with schematics or more information regarding the YIG  HP 5086-7833.

My plan is try to replace the YIG with a similar 3Ghz  to 7Ghz and lower expensive unit, but first I must confirm if the driver board is working accordingly.

Kind regards.
   

[taydin]

I haven't gotten a chance to work on mine for a while, but hopefully that is going to change soon ...

First I will fix the power supply. I'm going to wash the entire unit in my ultrasonic cleaner, which should get rid of all the electrolyte that the old caps pissed all over the board

Next I will check the YIG oscillator just like you did. Good to know that somebody else is working on the same unit. We can share our finding and we can ask to do comparison measurements. Chances are what's working here doesn't work there, and vice versa 

[collett.marcelo@gmail.com]

Hello !

 
Last week I got a equivalent YIG covering 2 to 6,6 Ghz and I did all wiring to SA.

After a got good results for YIG cal but could not got frequency and level calibration...

I checked more for the cause and I discovered that on the SPANS below 10 MHz the center frequency is very unstable.

The problem looks related to the FM coil but I have no idea it is the YIG itself



Thank you for any comments or ideas !

 

Regards.

Marcelo

[taydin]

Finally got a chance to look at this again. After giving the power supply an ultrasonic bath, the power supply is still behaving the same way. All outputs measure normal when not loaded, but the PSU cuts out when any output is loaded. So it seems I need to build an equivalent PSU for this SA.

I have done the cal tests and both frequency and level CAL's are failing with SRQ 110.

I have checked the output of the YIG using my scope, while the SA was scanning the entire span. The YIG output always stays very close to zero So I guess I will either need a new YIG, or build an equivalent circuit in there (perhaps some kind of high precision VCO).

I have seen YIG's for this SA for sale on ebay, but those are not new and are probably salvaged from other old SA's. Chances are they don't work, either.

[taydin]

Spent some time reading the "performance verification manual" of this SA. And good thing I did! Realized that I have measured the YIG output not correctly. The RF front end of this device is quite involved. It has two LO's, and two mixers. One is for the low band (0 - 6 GHz), and the other is for the high band ( 6 - 22 GHz). For the low band, the YIG oscillator is used for LO generation. For the high band, a YIG filter is used to isolate the third harmonic of the YIG oscillator output.

Based on this new information, I have reassembled the RF front end and measured the YIG output at the CORRECT SMA port, and I have seen 2.85 GHz output using my scope. The amplitude, as measured by my 1 GHz BW scope was -0.5 dBm, so probably closer to +10 dBm in reality, which makes sense for YIG oscillator. So that was a big relief

[taydin]

A few pics of the RF front end assembly:





The YIG oscillator and YIG filter

[taydin]

After putting the YIG oscillator and filter back in, I started to see of the step attenuator at the input is working properly. Removed the rigid SMA cables from the input and output of the 0 - 70 dB attenuator, and connected my signal generator to the input and the scope to the output.

The attenuator's control port was still attached to the SA, so I was able to change the attenuation using the SA's control menus. Applied 20 MHz, 0 dBm test signal to the input, and at 10 dB attenuation was expecting to see - 10 dBm at the output, but saw much, much less than that. In the end, it came out that one of the 20 dB segments in the attenuator is stuck, so the attenuator seems to be adding +20 dB more to whatever is programmed.

I adjusted the reference level setting in the SA to compensate for the step attentuator extra attenuation, and i was able to see a peak for the first time! The peak level was completely off, and the frequency indicated by "peak search" was was by 2 MHz from 20 MHz, but I'll worry about that later. For now, my focus is to get the step attenuator to work. One step at a time 

[taydin]

This is actually good news! Step attenuators are much cheaper than YIG's. But I don't know if these are available on ebay, need to check. But I've also seen videos where people attempt to repair these.

[taydin]

There were two observation that initially seemed strange to me. Below is how the spectrum looks like when it's doing a sweep of the entire 22 GHz span and nothing is connected to its input.

1) The spectrum is drawn outside of the grid. I think this is because of the step attenuator working incorrectly, and once that is fixed, I think the graph will move into the grid.

2) The spectrum has an unexpected step at about 6 GHz. I interpreted this as a possible damage in the mixer, but now I'm thinking isn't probably the case. The RF front end has two separate paths, one low and one high, so I think that step corresponds to the point where the sweep changes from low to high range. But I won't be sure until I feed this a slowly sweeping signal between 0 - 15 GHz.

[LatethanNever]

Hi, Sorry if I am hijacking this thread.

I recently acquired an HP 8592B spectrum analyzer and it is in good working order.   However, it has no options installed but I would like to find a way to connect it to a computer to control it and/or pull data from the unit.  There is no HP-IB interfce (Option 021) and no RS-232 interface (option 023).   There is only a 9-pin "AUX Interface".   I've skimmed through the 8592B Spectrum Analyzer Installation, Verification, and Operation Manual https://literature.cdn.keysight.com/litweb/pdf/5958-7098.pdf and I can't find much information about this connector.   I was hoping it is some sort of serial connector which would give me some control/access.

Does anyone have any experience about this "AUX Interface"?

Thanks