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- HP8924-Family-Spectrum-Analyzers
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Re: HP 820 assembly level repair manual
¿ªÔÆÌåÓýSomeone in the USA should get the manuals as he is thinking of recycling the paper and thinks someone will want the empty ring binders Unfortunately I am in the UK ? From: [email protected] [mailto:[email protected]] On Behalf Of Wallace Gasiewicz via groups.io ? Just for your information, apparently this fellow in the US has a FREE hard copy of the assembly level repair manual: ? |
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FOR SALE: HP8924C CRT Module
I have a 8924C CRT module available for a nominal amount plus shipping.?
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It has light burns but this doesn't really affect the operation.? A few years ago, I changed it out for a new module but when in operation I didn't notice a lot of difference.? I could probably could have left it alone.
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Drop me a note if you can use it.
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KE6CD |
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Re: HP 8935 Ext Ref Problem
The 8935 board I have is not identical to the 8920 CLIP Schematic. So I cannot be sure.? There is a signal to the oscillator that appeared to be high when the ext ref? was plugged in. a pull down resistor of about 500 R at this point solved the problem.? There is also a big cap at this point which is not on the schematic, It was fine.? I think there is something amiss in the oscillator itself.? however works fine now. I have the high stability OCXO not the TCXO. Wally KC9INK
On Thursday, August 22, 2024, 12:48:47 AM UTC, Hank Riley via groups.io <n1ltv@...> wrote:
Wally,? good news, but please tell us how it's working again. |
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Re: HP8924C duplexer tuning setup
¿ªÔÆÌåÓýGood afternoon and hello Robert. Will these files work on the 8920B? ? Thanks, John WR0J ? From: [email protected] <[email protected]>
On Behalf Of Robert G8RPI via groups.io
Sent: Saturday, August 3, 2024 7:15 AM To: [email protected] Subject: Re: [HP8920/8935 Family] HP8924C duplexer tuning setup ? Using the HP RF Tools software greatly simplifies this proceedure. And as the 8924C uses PCMCIA cards it's easy to do. The progams are here ? ? ? ? ? ? ? ? ? ? ? ? ? ?/g/HP8924-Family-Spectrum-Analyzers/files/RF%20Tools%20&%20NA%20FM ? Ideally use a static RAM? (SRAM)? PCMCIA card.? If you don't know how to do this I can supply a linear FLASH card with the program already installed. ? Robert |
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Re: HP 8935 Ext Ref Problem
¿ªÔÆÌåÓýHi,
either your HP 8935 or the external frequency reference that you a using is off frequency. A lot of HP/ Agilent test equipment will reject the external?frequency reference if it is off?frequency, sometimes only as much as a few hundred
hertz. If you are sure that the external reference is on frequency, do a frequency check of the generator output of your 8935. Sometimes just a adjustment of your 8935 to the correct frequency is all it needs, or it may have a faulty internal reference fault,
eg, a faulty oven reference oscillator, which is common on high hour equipment.?
I believe the 8935 frequency adjustment is done electronically via a test function called PERCAL.?
James?
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Re: HP8924C duplexer tuning setup
toggle quoted message
Show quoted text
-------- Original message --------
From: mark weisenfeld <mark.wfeld@...>
Date: 8/3/24 10:32 AM (GMT-06:00)
Subject: Re: [HP8920/8935 Family] HP8924C duplexer tuning setup
Guys!??
This old video is EXACTLY what I wanted.
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Thanks lobos305 for that link. I am now familiar enough with the interface that the blur is inconsequential. I can see now how to move the marker in duplex/SA and scope views. Eyes also opened up to quite a few other measurements (sinad)
that I had not looked into yet, but was ready to try.
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The setup with auto offset is cool; I'll have to remember that one.
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I was not doing the duplex tune exactly the same way, but I now see that I was on the right track, my adjustments are good, and now that I know how to move the marker I can tell "how close" I was to the native freq of that duplexer.
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...and I am only half-way through the video.
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THANKS a Bunch!
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Re: HP8924C duplexer tuning setup
Guys!??
This old video is EXACTLY what I wanted.
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Thanks lobos305 for that link. I am now familiar enough with the interface that the blur is inconsequential. I can see now how to move the marker in duplex/SA and scope views. Eyes also opened up to quite a few other measurements (sinad) that I had not looked into yet, but was ready to try.
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The setup with auto offset is cool; I'll have to remember that one.
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I was not doing the duplex tune exactly the same way, but I now see that I was on the right track, my adjustments are good, and now that I know how to move the marker I can tell "how close" I was to the native freq of that duplexer.
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...and I am only half-way through the video.
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THANKS a Bunch!
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HP 8935 Ext Ref Problem
My 8395 works fine with the internal reference and I did ti alignment with an external source.
However it does not lock with a 10 MHz external signal - shows "unlock" but once in a while it will Lock.
If I put in a 10.000.022 MHz signal it will lock to that...but of course all the signals and freq counts are off also...
I have the Temp Comp Xtl. 1813-1106
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Any Suggestions?? |
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Re: HP8924C duplexer tuning setup
Using the HP RF Tools software greatly simplifies this proceedure. And as the 8924C uses PCMCIA cards it's easy to do. The progams are here
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? ? ? ? ? ? ? ? ? ? ? ? ?/g/HP8924-Family-Spectrum-Analyzers/files/RF%20Tools%20&%20NA%20FM
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Ideally use a static RAM? (SRAM)? PCMCIA card.? If you don't know how to do this I can supply a linear FLASH card with the program already installed.
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Robert |
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Re: HP8924C duplexer tuning setup
Mark, How close do you think you are?? Try to include numbers (even approximate ones) when posting about these HP instruments. Maybe you could post a picture of the cavities, too.? Brand? Hank ________________________________________________
On Tuesday, July 30, 2024 at 12:50:11 PM EDT, mark wrote:
I am seeing the characteristics of the cavities, their preferred operating frequencies are close to 443 & 448, but I can only get close to the deepest nulls they are capable of providing. So, once again, I am afraid my ignorance may be hiding some better techniques, and better results.
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Re: HP8924C duplexer tuning setup
Yeah, that is a good explanation of the generic process.
I also found : ?
I was able to get the 8924C to generate a signal at a certain level on the center frequencies I desired (443 & 448Mhz) and watch the spectrum analyzer dip and distort by adjusting all the cavities - just by fiddling around.
By connecting the input and output together (bypassing) I was able to determine that my straight-through loss was about 11.5db and by subtracting that from high pass losses I see that the duplexer is losing about 1.5db on the TX & RX high pass. By swapping the SA input and the dummy load on the duplexer, and changing the center frequency between 443 and 448 I was able to achieve nearly -60 db (-53 & -57) rejection on those frequencies while maintaining the 1.5 or so high pass. This process was every bit as challenging/tedious/fascinating as they say.
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I think I have it figured out, but I am such a noob to this there must be some better was to use this thing, like being able to move the marker without plugging in a new center freq.?
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I am seeing the characteristics of the cavities, their preferred operating frequencies are close to 443 & 448, but I can only get close to the deepest nulls they are capable of providing. So, once again, I am afraid my ignorance may be hiding some better techniques, and better results.
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Since I see slightly higher rejection from one path than the other I am considering swapping the repeater TX & RX frequencies so the slightly higher rejection is against the TX frequency coming back into RX. I THINK it is backwards now - but I may be remembering that wrong, another thing experience will remedy. (It will also help to not be doing it at 10:00pm)
SO anyway, What a great device!!!? I look forward to knowing more about what the hell I am doing -AND- how to make that thing work for me.
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