I did catch some 432 models have a sticker warning they are prepared for different, longer cables, and cable long must match what the sticker says for it to work OK. Mentioning it here, just in case.
Quote...the probability of some guy being here, having both 431 and 432, is probably next to zero.
I've also got a 431C power meter and two 432A power meters and two 478A sensors. One of the 432A power meters is as new and unused and has the original HP seals and stickers on it. The 478A sensor is still factory (vacuum) sealed in its packaging and so is the sensor cable and the manuals. It's never been unpacked and used. It must have been stored from new and forgotten about.
Quote...the probability of some guy being here, having both 431 and 432, is probably next to zero.
I've also got a 431C power meter and two 432A power meters and two 478A sensors. One of the 432A power meters is as new and unused and has the original HP seals and stickers on it. The 478A sensor is still factory (vacuum) sealed in its packaging and so is the sensor cable and the manuals. It's never been unpacked and used. It must have been stored from new and forgotten about.
You just achieved with me what Pavlov achieved with those dogs...
Every year or so I use the other 432A + 478A to check the 50MHz 1mW source from my power meter using DC substitution. I've done this for quite a few years now. I can show you how I do it when you get your 432A up and running. I follow the factory instructions and created a spreadsheet to do the calculations.
This is for sale locally on Craigs List. Though I have two 438a, I think that is the number, dual channel power meters, plus a module in my MMS, I've not run into the thermistor mount as he calls it, on this model.
c) after the 2200 ohm resistor, a battery is placed against the voltage coming from the power supply, I guess it's to lower the 29V so the suggested DVM (HP3440) is able to get in a range where it can resolve 1 mW
The value of this bucking voltage should be such that voltmeter resolution down to 0.001 volt is obtained.
1) Is it worth the hassle if thermistor mount is able to be coarse/fine zeroed? I guess probably not.
2) I guess that 2200 resistor is there to limit current/voltage. So having a good modern power supply with CV/CC, one wouldn't need that resistor, provided the power supply is set to the correct V and I output --- or is it there to make sure there aren't any peaks able to damage thermistors?
3) Having not a 3040, but a 3456 6-1/2 digit DVM, surely that bucking battery wouldn't be really needed anymore?
Up front I have not tried what you are showing so my "guesses" may be way off - Before you go slamming V/I through the 478A I'd wait to get a consensus or commentary from someone who has done this.
The battery was chosen to achieve a 1mV meter resolution - From the manual:QuoteThe value of this bucking voltage should be such that voltmeter resolution down to 0.001 volt is obtained.
#1 - No, if the mount zeros then it is pretty much working - TBH I've never seen one of these where it is working but 'almost failing', it seems that this is possible and may have been more common once given that the manual provides an explicit procedure to take to address but I think it is a pretty low chance case - YMMV as will others
#2 - +29V seems to be one of those numbers that are oddly specific - I would not be surprised to find out that the thermistors need to be seeing a certain amount of voltage/current so that the compensating thermistors react correctly to what would be expected from the thermistors exposed to the RF field. I would love it if someone had the real explanation for this and could share with us.
#3 - Most likely not given what the manual was saying earlier but you will still need to ensure that the V/I through the 478A is within spec - You could certainly math that from the manual but if the 478A was working then I lean towards this being a bit dodgy.
Sorry I couldn't provide more clarity - Interested in seeing what more experienced members say.
G0HZU, could you please provide more info on how you use the 432A + 478A to check the 50MHz 1mW source using DC substitution. I do have similar needs and can probably benefit from your experiences.
Yeah, it seems to be for 431.
Well, it seems I found the limits of the forum. Of course, the probability of some guy being here, having both 431 and 432, is probably next to zero. I have never seen the slightest mention of cables for 431 and 432 being different. So, here it remains this piece of information. Hope it will useful for somebody in the future.
I already ordered another cable, this one no only has the notch, but also has golden pins
Best wishes