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Have a failing/failed cooling fan from a HP machine with OPT 003 (400 Hz), which appears to apply to the type of fan installed. Are there any requirements (trying remember undergraduate EE class that described analysis of induction motors - does that describe a typical cooling fan of this sort? - but that is digging waaaaaaaaaaaaaaaaay back to the 70s... Should a generic 120 VAC 60 Hz fan of sufficient air flow be acceptable, or do I need search for a fan designed to support 400 Hz?)

Have a HP 8485A sensor I bought used, turns out it had been damaged due to overload, seller refunded, now have a physically nice but electrically dead HP 8485A sensor. Have a HP 8481A sensor surplus to my needs. I'm interested in the possibility of converting my 8481A to an 8485A (3.5mm male connector), albeit not calibrated, in lieu of the cost of buying a working 8485A. Found a Keysight publication that seems to be quite comprehensive coverage of this era sensor: https://www.keysight.com/us/en/assets/9018-04931/service-manuals/9018-04931.pdf?success=true This is titled "Keysight 8480 series coaxial power sensors operating and service manual." I wasn't aware the manual existed; it is current publication from Keysight. The manual has pretty extensive "how to disassemble and reassemble" and other maintenance activities. The underlying thermocouple sensor element appears to be the same part number for 8481A and 8485A, so this brings me to my question - could I create a thermocouple sensor with a 3.5mm HP male connector that could subsequently be recalibrated and used as an 8485A? I've searched and haven't found any reports of the practicality or result of actually trying this procedure. Thanks for any comments, observations, or requests for clarification.

Hello, I have picked up an oscilloscope 54810 I have some problems on it, but it’s settled. Meanwhile, I tried to put the graphics card 54810-66505 on another motherboard (which also had its video output built in), for tests. Since the video card no longer provides output. The screen is black. If I put an old video card trident, the screen works. I think my manipulation must have "written" information in the chip 65550. (Some register?) What manipulation could reactivate it? NB: the card is visible in the bios pnp/pci parameters Your opinion. cdt

Hi guys, as you all know, the HP 435A, 436A, 437A and so on are quite nice power meters and the meter itself is availabe at quite low prices. However, the power sensors are quite expensive. I own a 8481A and a 8484A, both in nice and working condition, but I don't want to damage anything so I treat them like raw eggs and handle them extremely careful. So I always thought whether it would be possible to make a own diode power sensor which is compatible to the HP 436A. This would have the advantage that the 436A could be used (and therefore its HPIB capabilities), and if it works with the 436A, it will do so also with the other meters (and possibly others, I don't know). Further, the homebrew power sensor would be cheap and if it breaks, no matter, it can be repaired easily. So today I spent a few hours on making my own power sensor. I checked the schematic of the 8481A power sensor, and I did basically the very same. I came up with this schematic: (I don't want to waste valueable web space for the group, so I uploaded the high resolution pictures to my webspace) https://hb9fsx.ch/wordpress/wp-content/uploads/2018/11/20181117_173101.jpg The letters on the right side are the connector pins for the HP 436A, of course. Then I made a quick 'dead bug' style prototype, as follows.... (please don't laugh at me :-) ). https://hb9fsx.ch/wordpress/wp-content/uploads/2018/11/20181117_170657.jpg I connected to the 436A and I also installed a SMA 30dB attenuator at the input and connected my power sensor to the power reference of the 436A. At first, the readings were quite off a bit, but using the little trim pot on my PCB, I was able to precisely adjust the gain of my sensor such that the reading on the power meter was exactly 0.00 dBm. I then connected a signal generator to the power sensor and tested various power levels between -10dBm and +20dBm. Incredible, but my power sensor was accurate to 0.1dB! I also tested different frequencies between 1MHz and 2.6GHz. The flatness was not extremely good, but between +/-1dB. So, basically, the concept seems to work. I also tested different ranges for the power sensor - there is a 'mount resistor' inside the HP power sensors (8481, 8482, 9494, ...) which tells the power meter which range the sensor uses; the meter then internally adjusts the gain according to the power sensor range. It appears that it should be possible to home brew such power sensors. However, at the moment, I have two issues: a) the auto zero function does not work - even if I run the autozero feature, the power meter afterwards displays -13dBm anyway, so I cannot properly zero my power sensor. At the moment, I do not understand why this is so. Has anyone on the list an idea? b) I don't understand exactly how the amplifier using the NPN transistor works. When I was adjusting the gain of my sensor, I tried to change the collector resistor (330 Ohms), but this had almost no effect on the gain. The emitter resistor (1k Ohms) also had only little effect on the gain. Only when I placed the pot where it is now I was able to adjust the gain in a wide range. So it basically looks to me like this amplifier is a common emitter amplifier, with the gain being RC / RE, is that true? why then is a feedback from the emitter required to the meter? Thanks for any hints, tips and so on, Tobias HB9FSX

Hello, Any one have a service manual for a HP 4934A? An electronic copy? Any good ideas where to find either a paper or electronic copy? It is for a TIMS. Transmission impairment measuring set. thank you for any help Brian

Hi Fellows, Last offer before retirement... CLIP P/N is E4400-90336 Model covered: E4400B, E4420B, E4421B, E4422B, E4423B, E4424B, E4425B, E4426B, E4430B, E4431B, E4432B, E4433B, E4434B, E4435B, E4436B I’m sure that also E44xxA series are covered because i have also ESG-D3000A = E4432A and boards/modules of this guy are also covered. Keysight seems didn’t put E44xxA series in the Find-A-Part database because is older than B series. Was a lot of work to scan over 1000pages...I'm asking 35USD or 30EUR When we did a scan, not optimal scanner parameters were used... scanner ignored inductors (spring like lines) but references and values are there. Once we saw this, was to late to do job again. Zip file size is about 122MB I told, not perfect scan quality but totally useful, please check attachment. Please contact me on my private email: milan.vasic@... BR, Milan

Hi can someone tell me what thread the screws are that hold the back panel on HP8656. I am assuming they are 5/32 as 3mm and 4mm metric are either too small or too big. or wrong thread Are the UNF , UNC or something else? imperial thread screws are not common in Australia, and I have lost all teh screws out of the back of my sig gen. I think the ones i ordered were bsw and of course don't fit Wayne VK2WDE

HP series 200/300 and Plotter Manuals PM direct for offer… 7470A Plotter, Statistics, Graphic Presentation, Project Management, Basic 4.0… Interface Techniques, Utilities, Waveform Analysis, Graphic Techniques, Asynchronous Terminal Emulator Thanks, Alan

The following items have been added to the Files area of the [email protected] group. /All HP, Agilent and Keysight instruments in folders by part numbers/3000 to 3999/33xx Level detectors and synthesizer level generators/3336 A-B-C Section VIII - Service.pdf By: Harold Foster <halfoster@...> Description: Combined schematics and diagrams for the "Section VIII - Service" portion of the 3336A-900000 manual

Radu Bogdan Dicher <vondicher@...> added the photo album Microscope

I might be able to get an HP 8511A...

Went to great lengths to create PyVISA program to read using the GPIB the x4 parameter S-parameter data from the HP8510C. This eventually would read consecutive 1701 point sweeps in a round 5 seconds using the HP binary data format; ASCII data formate took much longer. That was for uncalibrated data. However, when i tried to read TRL calibrated data it would take over two minutes to read the data. The obvious solution then would be to just read the uncalibrated data and perform the TRL calibration in the PC. I could trawl through endless papers to find a suitable mathematical equations to code up in Python. From what i gather, mathematically its quite complicated, solving something like 12 simultaneous equation, clearly doable, but i've also got a massive list of other stuff to do. Might anyone have an algorithm to perfor the TRL calibration, or know where i might find this? many thanks, N

Hello Forum, I think I posted this before but no harm in bumping... Together with an HP8568B, I got a number of 3?-inch disks: 85863-10027 Rev C : 85863A Opt 630 Basic Software Library 08568-10004 Rev A: HP 8568B Spectrum Analyzer Operation Verification 08568-10004 Rev A: BASIC Operation Verification for 8568B 85863-10027 Rev B: 85863A Basic Software Library for 8566A and 8568A Opt 630. All disks (C) 1984 and two of them marked "For HP 9000 Series 200 Computers with Basic 2.0 or 3.0 O/S Any interest in images? I do not know if any data remains on them. If so, How to read and make images on a PC running XP or W7? Cheers Ulf Kylenfall SM6GXV

My 8643 failure message indicated 5V supply failure. Voltage at test point measured 4.9 volts. I replaced all the capacitors in both switching supplies of the 8643A. Both supplies checked out OK before capacitor changes, and OK after capacitor changes. But I'm happy it has new capacitors. The battery voltage was OK, but being old and not interested in leaks, it has a new set of 3xAAA in little plastic holder. After reading about tinned Molex connectors developing voltage drops I sprayed DeOxit on pins of the power supply connector, and both input and output connectors of the power filter board. And of course the cable pins that plugged into those connectors. Power supply and filter board input connectors were tinned pins. Pins on the output end of the filter board were gold. Did the best I could, but it wasn't as good a job as I would like to have done. NONE of the connector bodies were discolored. There was maybe 1/4 volt drop, and not that many hours of use, before I took it apart. Probably not enough time and heat to discolor the Nylon. Applied power, and test point now measures 5.10 volts. So looks like it was voltage drop in the tinned Molex connectors. No error message. While I haven't checked exhaustively to verify everything is working, but I expect it's OK again. THANK YOU GUYS FOR POINTING TO THE CONNECTORS Regards - Bill W7AAZ

My 8643A started doing a "recalibrate" every time I turned it on. Once the 8643A completes that "recalibrate" its RF output and frequency are OK, although I have not tested every aspect of modulation, sweep, etc. I assumed it was failure of the memory backup battery, but it was original and OK. But old and leakage would be a disaster, so replaced the battery with three AAA NiCad. Still "recalibrated", as expected. The fault message at the end reported the 5.25V supply was not within spec. I checked a test point at the output of the power supply filter board and found less than 5.0V. Having experience with tired computer grade capacitors I assumed that would be the case here. Surprise: no transformer supply with big caps, just two switchers. I pulled both switching supplies and found that both the oven switcher and the main 5V/15V supplies voltages were OK. Particularly the 5.25 I tested with a 2A load current and it was perfect. All capacitors in both supplies with Nichicon 105C and operating at a fraction of rated voltage. Nonetheless, considering the age and the disassembled state of the 8643A I have all new capacitors (again Nichicon 105C which were also my choice when I was working). I have replaced caps and retested the 24V oven switcher. The last capacitor for the main switcher is supposed to arrive today and I expect the main supply will test OK by tonight. Out of curiosity I tested the removed capacitors and all but one exceeded the rated capacitance and had tiny leakage current. It appears I am losing about 300mV between a supply at 5.25 volts and the connector at the output of the power-filter board. Something drawing too much current? It would have to be a seriously large amount of current. That seems unlikely given that it seems to be working. All DC supplies pass through a passive filter board with series inductors, shunt capacitors. With the supplies still out and the filter output connector disconnected, I will measure the shunt impedance of that filter board. Anyone with 8643A experience have any other ideas? Bill On 3/7/2025 7:51 AM, AArnaud via groups.io wrote: