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Since Agilent continiously ups the spare part prices and discontinues parts it has become more and more important to go past normal repair practices. Step Attenuators for example can be repaired without any special tools or cleanroom enviroment ! Lets take a look at the failure modes first, there are a few: 1.) Blown pads Usually common with spectrum analyzers if a level past the damage level of the attenuator was applied 2.) Cracked pads, pad has developed a hairline crack due to mechanical stress ! 3.) Improper contact, the contact in between the attenuator and contact fingers is disturbed. 4.) Stuck solenoid Quite common if attenuator hasnt been used in awhile After we remove the attenuator from the instrument the first step is to obtain the pinout and build us a little test bench consisting of a powermeter and a signal generator, the good old 8481D or 8484A will do nicely, if you dont have a sig gen use the 50MHz calibrator output of the 435 or 436 or similar model, connect the cal output to the 30dB pad connect the sensor and zero and calibrate meter, the meter will read -30dBm. Disconnect the sensor from the attenuator and insert the Step Attenuator, set step attenuator to 0dB, note the level on the powermeter, now switch in the attenuator sections one by one measure and note the level, 70dB attenuators are comprised of a 10 20 and 40dB Pad while 110dB Attenuators normally comprise of a 10 20 and two 40dB pads ! check every section individually, you should hear a click as you enable each section, if you find a bad section note the value it should have if all sections appear to be good repeat the test at a higher frequency using a sig gen, if everything appears to be ok at low frequency then most likely you have attenuator that just needs cleaning. Now lets take the attenuator apart, looking at the top you will see a nut on each SMA connector, remove this nut this will allow for you to remove the nameplate, under the plate you will see a wealth of allen screws, remove those but note that the screws close to the SMA connector are shorter than the other ones. Now look at the small sideplate, not the one with the ribbon cable but the other side - there are 4 small allen screws, remove those and then remove the sideplate, careful not to lose the little wire mesh here ! now slide out the u shaped cover and remove the top side. You now have two parts, one beein the bottom side containing the solenoids and the other one beein the top part containing the attenuator pads. First lets inspect the pads, you can measure them with a ohm meter, they should measure in the vicinity of 50ohms , except of the 10dB pad which can measure up to 70ohms or more. Inspect the pads visually, are there any burned or cracked pads ? if all pads look ok and check out at DC take a surgical swab and isopropilic alcohol and carefully clean the contacts pads on the attenuators. Next look at the contacts, enable all solenoids and observe the position of the contact tongues, they should be slightly above the surface of the block, carefully clean the contact tongues with alcohol, be careful not to bend them. next put the solenoids back into the 0 position and look at the top of the solenoids, you will see two little white plastic rods where those meet the solenoid you should see little rubber rings , there are 4 of those on each segment, usually over the years they go briddle and then disappear, with those rings gone the attenuator wont make contact anymore, you can buy the rings from watchmakers supply stores as they are beein used for sprocket gaskets ! Now if your gaskets are there put the attenuator back together after you cleaned everything and it should work now. If you have a broken or burned pad dont stress over it the pads are used in all HP attenuators so just find a attenuator on ebay and take the pad you need out of it, you can also buy pads from agilent however be prepared to pay $100-150 per piece

I got a HP8754A recently that mostly works but seems low on available trace intensity. Maybe it just needs some internal adjustment, or maybe the CRT is weak on emission. Now that I have this one, I've cancelled a project I was planning to fix an old HP8407 VNA with 8412A CRT mag/phase display. I junked it all out and it turned out to be the right choice, since I found all sorts of corrosion in places inside, and broken items, which would have been a PITA to restore anyway. I would have also needed to acquire or build a suitable source for it. The 8754A has everything in one unit sufficient for mag/phase transmission measurements on RF parts. It will be committed to the component testing dept. I saved the CRT from the 8412A. It seemed to be pretty decent in brightness, so maybe it could be a spare for the 8754A if ever needed, with certain limitations. The screens appear to be basically the same except for marking details, and the 8412A one does not have the circular or radial graticule lines for polar display. In the manuals I found the CRT pinouts appear to be the same, but the listed cathode supplies differ by 100V - could just be typos, or different design choices, or maybe due to different phosphors (P39 v. P7?). I believe they are both the same basic CRT, just with different faces, so should be interchangeable. I found some CRT info here in the files department. It says the 8412A used 5083-9081/P7, and the 8754A used 5083-1890/P31. The manual for the 8754A says its standard CRT is P39, while the 8407A doesn't say anything about the phosphor. I know they're both green, and would have gone with long persistence for this application. Anyway, I can accept the differences if something should happen to the original CRT, and the spare is close enough. Does anyone know details of the HP CRT lines, or where more info can be found to clearly determine (electrical) interchangeability? Ed

Would anyone have an example cal file they can share? I’d like to create one for my hardware

Hey All, I noticed what looked to be a zero issue with my 435B, so I thought I'd run it through the zero carryover test (OSM 4-6) to see what was going on. While the meter meets all the ranges given for zero carryover, it occasionally doesn't meet the requirement: 4. Press the front panel ZERO and wait for the meter indicator's position to stabilize. Verify that the DVM reads 0+/- 0.9 mVdc. Release the ZERO switch. My output seemed quite noisy, so I used the statistic function to look at it over 100 samples, and what I saw was: Max 0.533 mVdc Min -1.006 mVdc Avg -0.150 mVdc If I had been quick to look at it, then I could have moved on to the next part of the test and never noticed that over some time it exceeds the +/- 0.9 mVdc requirement. Should this be less noisy? The only fix from the manual is to change the factory selected resistors A4R12 & A4R16 (the A1 assembly is a recommended factory replacement), and it does pass the actual +/- span for each step of the range control so I'm hesitant to make any changes to those. Any thoughts or guidance appreciated. TonyG

Having done enough (red) eye cracking smd soldering jobs or inspections in case of suspected failure (cold joints, etc.), I've decided to invest a bit on a better optical setup. There's plenty of cameras on the marketplaces and retailers out there, but what are some better choices? Good experiences with some specific models? Also, what to watch for? Specs, minimal magnification that crosses over a good threshold? I have a couple of large screens at my bench - I'm thinking this will be best done by shooting this over to one of those. USB, HDMI?... Lighting/LEDs making a significant difference? Thank you for your input. Radu.

Hello, I need to disassemble the HP/Agilent 8495B attenuator, there are no visible screws, how can I do it if I need to service the attenuator ? Thanks in advance!

Hey All, I asked over on VinHPcom but apart for a pointer to the 17090B Software up on HPMuseum I didn't hear much back, so I thought I'd ask here as well. The C version of the software apparently works with Series 300 machines so I'm interested in trying to see if it works with my Viper machine. So if anyone has a copy I'd appreciate it if I could snag one from you. Thanks, TonyG

Hi Alex, I used a demo version of Benchlink 33503A Pro to create triangle wave files in *.wvf, *.arb, and *.barb formats. For the 33522A, the waveform will appear on both channels simultaneously. Yves De : [email protected] <[email protected]> De la part de TomS via groups.io Envoyé : 23 mars 2025 04:19 ? : [email protected] Objet : Re: [HP-Agilent-Keysight-equipment] Keysight 23522a Binary Arb Files Hey Yves, I found a threat for a 33210 where you created a testfie for a User. Is IT possible that you create a small barb File with all possible Parameters for my 33522a? Thanks in advance Alex

Does anyone have handy the HP part number on the interface IC used in the 10248 series of logic analyzer data probes? The manual on the probe has all part numbers listed except for the IC that is part of the PWB assembly. I once came across a HP part number 1820-0919 that was believed to be the number but it crosses to a Motorola MC1650L which is a dual A/D converter, an obviously wrong part. Thanks, Greg

About a year ago one of my E4421B signal generators developed a display contrast problem. I left it for a while and then decided to see what info i could find about the problem. After a while i decided i needed the services of Milan for the CLIP details, this was neatly done (thanks Milan). This info also was left for a while and then i finally took the cover off to see what was happening. As previously reported Q601 had an open BE junction. Mmm strange. But prior to this i measured some weird voltages on the LT1170 regulator and even worse an unusual to me configuration, the ground tab is connected to the 1mH switching inductor. So i confirmed the DAC was supplying a 0 to -10V control signal from the front panel-good but the output from the TL074 was jumpy as was the output from the LT1170 regulator with supplies of up to -46V being measured. Q601 was replaced (not the best thing to do) and the display was back for a minute and then it all went wrong again. Working at the LT1170 was not easy due space and depth issues so i rebuilt the supply on stripboard to emulate the problem. So i couldn't get these weird varying voltages even thought the control signal was fine. Almost there so it was the Schottky diode CR607 that was the culprit. The excess voltages explains the demise of Q601, C651 the 47 uf output capacitor was also replaced. I would suggest to any one with this problem to immediately connect a 24V zener across R625 the 2 watt 1K5 resistor and remove the 15 way flat ribbon going to the display to avoid damaging it whilst affecting repairs as $350 is a high price for a new one cheers Geoff GI0GDP

HP list, the extension cables have been sold, Thanks for the responses, Gary WA2OMY

Not strictly Agilent/HP, but I recently bought a 2nd hand N-Type cal kit for the 3 HP VNA's I have. I did originally want a new kit from Kirkby Microwave, but after 3 or 4 emails over the course of a few weeks with no response I gave up. So I have this 2nd kit, the pin depth checks out ok on it. Problem is the foam has deteriorated in the case, and some of it has got into the connectors. I've tried IPA with a swab and got the worst of it out, but some stubbornly remains. Any suggestions to dissolve the black sticky residue? Or otherwise clean these connectors. Problem number 2 is creating a definitions file for the 8519C, 8753C and 8571A although 85054A