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I would tend to trust the 8920 more than the Bird. IIRC correctly the Bird wattmeters are +-5% of full scale ...not sure what slug you have in the Bird .? If that's a 100 W VHF slug you are +- 5

Hi Bill, I listen to the normal gaggle of 2m repeaters so you can find me there. Tied up with WARG (again). Re your calibration against the Bird, is the Bird a good reference? Happy to have a chew of

Your Bird 43 is likely far less accurate than your HP. The elements include a potentiometer that is prone to shifting or going ‘rusty’. Some even fail open circuit. I took an element apart once

Hi Robyn, I see we are both VK6 ... and proud owners of these great instruments. I have been into the PSU?on my 8920A also.? At last all is going sweet. Perhaps we could support each other with some

Hello all, I have finally got my instrument going well, NO FAILURES? :) The one thing left is to adjust the reading to agree with the value of watts at the rf input, measured with my Bird 43 watt

Thanks, Yuri I suppose this 28C256 originally attached in the unit is broken. James

Hi John, Thank you. Hmmm, I gotta say that I'm suspecting the processor board right now. Yes, if the blank 28C256 is attached, checksum error only pops out for the very first time. After that first

Re: [HP8920/8935 Family] 8921A PCBs required Hello, Friday, December 29, 2023, 10:31:48, chinesejames1990 wrote: Thanks. Umm should I fiddle with my programmer to see if I can make some adjustable

When my 8924C died a few years ago, it was the little supply that keeps the OCXO warmed up. The rest of it wouldn't work without that. Getting to that little supply was a headache, but a couple of

Hi all, My 8924C died as well. Thankfully the excellent PDF and a $0.40 47 uF, 50 v high temp electrolytic fixed it.? What I will say is that you can remove and replace that cap in situ if you are

James, It sounds like you may have a bad processor board ...not sure if that is what also damaged the EEPROM.? Still could be another issues ....second on my list is the memory board? which on the

Hi Yuri, Thanks. Umm should I fiddle with my programmer to see if I can make some adjustable supply voltage on the chip? Thanks, James

Thanks John, Sorry for the late reply. Yes, I gave it another shot these days. First, I put an empty new 28C256 on and turned on the unit; errors remained the same. Second, I used another programmer

I can add a "me too".? My power supply died in 2009 and I paid someone to fix it, it just died again and this time I decided to tackle it myself this time. So far I've confirmed that was the problem

Dear Yuri, ??? You could send us the 28C256 IC and we could evaluate it at no charge. It's possible the IC is corrupt. We can read it and transfer the data to another 28C256 and see if that works.

Happy Holidays to all group members I am a proud new owner of an HP8920A. My main use will be for various amateur radio applications. I have been reading as much documentation as I can find on the

Re: [HP8920/8935 Family] 8921A PCBs required Hello, Monday, December 18, 2023, 16:43:43, chinesejames1990 wrote: My guess is CAL data is broken due to faulty original EEPROM 28C256. And the worst

replacing the calibration data is going to be tough for the whole unit.? It will load defaults when it hits a checksum issue ...every section in the cal data has a checksum it's so important.?

Hi all, First, I'd like to thank all of you who gave me ideas and clues. So here is what I've done these days: 1. I ran the selftest program contained in the ROM, and I almost every error message

Hi , I have a spectrum analyzer HP8920a and during the self test RF DIAG I have the message " VCO 1Ghz Not locked ". I checked at the board A15 and I have made some measurements. The output of the