HP8590A Spectrum Analyser - Installation and Initial Verification checks... - Page 1
Forum section: electronics / testgear

author: MostlyHarmless
author_rank: Newbie
timestamp: July 30, 2023, 06:14:01 pm
content: HiI've just purchased an HP8590A Spectrum Analyser from that well known auction site for over £250.00 including the postage and I'm working my way through the installation and verification manual to check it out as it was listed as Used / Fully working and it completes the CAL:FREQ and CAL:AMPD and the CAL:YTO DELAY all OKbut when i do the CONF TEST it throws lots of errors eventually failing and Throwing out SRQ 110 - Hardware Brokenso my first question is can this unit be described as Fully working when it fails the CONF TEST routine with a Hardware broken message being returned?and my second question is where do i start in restoring the unit to full working condition.MostlyHarmless

author: Uunoctium
author_rank: Frequent Contributor
timestamp: July 30, 2023, 07:42:01 pm
content: Mine is an 8591E, but there should be no huge differences.I have no access to manual at moment (stays on NAS in workshop) but if BW shape means IF filter curve is misaligend, you have to readjust. Instrument & manual guides you through that procedure - you only need a couple of jumpers. I used ordinary from pc-mobo.After that, an complete Autocal-procedure is necessary. Should run approx 30 Minutes. But before that, check the Cal-Out for proper frequency and Amplitude. I used a counter with ext ref +Rb for the 1st and generator with trusted outputlevel + 2Ch Scope for 2nd by simply overlay the two traces.If you decide to replace the backup battery on memory board, do'nt trust manual! There is something written, that the miracle supercap bypasses missing battery for a couple of days. This implies that it is working :'(

author: 807
author_rank: Frequent Contributor
timestamp: July 30, 2023, 10:16:58 pm
content: Did you press the CAL STORE button after the CAL FREQ & AMPTD had finished?While doing the CONF test, did you keep the CAL OUT connected to the INPUT connector? Did you see various signals on screen, similar to when doing the CAL test?Why do you consider SRQ 110 to be "hardware broken"?It cannot be described as "fully working" when it fails the CONF test. It's up to you if you want to try & realign it yourself, but I would still let the seller know. If you decide to keep it, then ask the seller for a partial refund.I bought an 8591E around 15 years ago. I remember having to align it. But mine failed on just 1 parameter, not many like yours. I remember having to glue some jumpers to sticks in able to reach the boards. It was relatively simple, following the instructions in the service manual.

author: MostlyHarmless
author_rank: Newbie
timestamp: July 31, 2023, 06:09:32 pm
content: Thanks for your replyI did indeed save the calibration after CAL:FREQ and CAL:AMPTD had finished.I did have the CAL OUT feeding into the RF Input when I ran the CONFIDENCE test.I consider SRQ 110 as "Hardware Broken" as that is what I found in the 8590A Portable RF Spectrum Analyzer Installation and Verification Manual, Appendix B, Table B.1Thanks for the advice on contacting the seller, I had provisionally decided I would keep the unit and ask the seller for a partial refund but your advice has convinced me that is the best way forwardI've attached an image of my Cal Out on the display, I've checked the Frequency and its near enough at 299.893 and it shows the fundamental(@300Mhz) and four more harmonics up to the fifth(@1500Mhz), so i think my Cal Out is good enough for nowthe first message i get out of the CONF test is POS-PK Fail, i guess i will start there using the Service manual and work my way through the Errors thrown out in the CONF test...Ok, so consider this Stoopid question no.1 - what is the huge peak around 8 - 10 Mhz, is it the internal 10Mhz reference?MostlyHarmless

author: ccktek
author_rank: Regular Contributor
timestamp: July 31, 2023, 07:06:14 pm
content: I used an 8590a for several years. Initially it had confidence BW fails similar to yours, but the CAL procedures passed. I got it to pass the confidence self-test by carefully aligning the IF filter/amps. The factory alignment procedure didn’t always work quite correctly, so I had to fudge some of the adjustments so get the bandpass curves to look right. (I’m not sure about the other fails on your list.)I found only one correct version of the service manual – it should be specifically for the 8590a, not the 8590 series. I believe this is correct:https://ia800206.us.archive.org/32/items/hp_8590A_ServiceGuide/8590A_ServiceGuide.pdfI agree with others that your 8590a can’t be considered to be fully working.The big spike on the left represents DC and is normal when the start freq is set to 0.Best of luck with your challenging project.

author: 807
author_rank: Frequent Contributor
timestamp: August 01, 2023, 09:23:15 pm
content: I've set my analyzer to the same settings as yours, & I notice that the harmonics of the reference signal on yours are much lower than on my 8591E. Don't know if that's normal for your model?As ccktek says, the signal on the left is 0 Hz. If you disconnect the input signal to the analyzer & set the centre frequency to 0 MHz, it should appear in the middle of the screen. If you turn on the marker, you can measure negative MHz.

author: MostlyHarmless
author_rank: Newbie
timestamp: August 01, 2023, 09:59:40 pm
content: Quote from: 807 on August 01, 2023, 09:23:15 pmi have been looking at the service manual for the 8590A i have and it shows a picture of the Cal Out signal as it should look and mine appears to have a higher noise floor than it should.the manual also shows some example calibration data sets and my data has RL-VENR values that are much too high at the bottom of the data set tableThe first test in the CONF routine is the POS-PK test which my unit fails, the manual gives me cause to think that the first mixers diodes may have degraded,I've watched a YT video where a guy had a very similar looking trace of his Cal Out and had Calibration data that was showing the same dodgy RL-VENR values

author: 807
author_rank: Frequent Contributor
timestamp: August 01, 2023, 10:37:16 pm
content: Ah, yes. Didn't notice your noise floor is about 10dB higher than mine. What does your display look like after pressing the "Preset" button? I've attached mine.I think I've seen that youtube video. Is it the one where he replaces the L.O. diodes with a surface mount dual diode?

author: MostlyHarmless
author_rank: Newbie
timestamp: August 02, 2023, 11:51:54 am
content: Quote from: 807 on August 01, 2023, 10:37:16 pmNot sure its the same YT video you mention, here's a link to it :its a three part series and he definitely sees an improvement at the endhe gets his RL-VENR values much lower than they were initially but still not as low as the service manual suggests they should be (but his unit also had an input attenuator module fault) so I think he has other hardware issues he did not find perhaps?)After pressing the "Preset" button my display is jumbled with correction toggled on, its not until i turn off correction that the display looks much better but the noise floor is much higher with the correction from the stored CAL DATA turned off, it looks to me like the correction is fighting the high noise floor?MH

author: ccktek
author_rank: Regular Contributor
timestamp: August 02, 2023, 03:51:33 pm
content: FWIW, I found a screen photo of mine when it was operating correctly.

author: 807
author_rank: Frequent Contributor
timestamp: August 02, 2023, 11:21:35 pm
content: @MostlyHarmless...yep, that's the video I saw. He replaces the 2 RF dides with an SMD dual schotky device.Definitely looks like your noise floor is around 8dB or so too high.The 300MHz CAL signal generator must be different on the 8591E. The harmonics are higher on my model compared to the 8590A.

author: Oldtestgear
author_rank: Regular Contributor
timestamp: August 03, 2023, 10:53:03 am
content: I just acquired one of these so will be watching this thread with interest. No idea when I will do a full check on mine but did see that the cal signal is correct & the full frequency range could be seen using a comb generator. Currently trying to coax a Datron 4707 back to life.Phil