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- HP8924-Family-Spectrum-Analyzers
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It's gone a little quit here lately
It's been quiet for a month now.? Would like to see some posting before January comes to a close. If you post just change the title to something that describes better what you're posting about.? ? We're slowly but surely gaining new members and months ago went past 200 for membership.? For some reason that I can't explain, we didn't get anywhere the numbers who came over here from the old Yahoo Group that I thought we would.? I expected 350 to 400 to start us off over here, but it was way less than that.? It didn't help at all that the group owner at Yahoo could never be reached, so the Yahoo member list could not be used to build this one. I may try one more time, with the email list I was able to piece together, to reach those several hundred people and invite them once again to come over here. Thank you to several of the present members of? HP8930/8935 Family for mentioning us in their posts to the giant HP groups.io.? Two of those people off the top of my head are Ralph M. and Robert A.? ?I think Ralph might also have mentioned us at Repeater Builder GIO. Hank |
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Re: File /8924C battery replacement.txt uploaded
#file-notice
Thanks Robert. You should add your additional information about the batteries to the part I wrote. The battery I used was the exact same type so I did not have to research it. The battery is made in Japan, but maybe the lithium causes some shipping problems to other countries. It would be bad if someone did use another type of battery and get the polarity backwards. I did notice the battery made the board a tight fit so if a replacement is much larger in diameter the board may not fit back in the slot. I don't know how long the battery will last but in the 8924C I have they are over 10 years old after I bought them. 73 de Ralph ku4pt |
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Re: File /8924C battery replacement.txt uploaded
#file-notice
Nice work. The circuit will work with 3V or 3.6V but polarity must be correct. The 3V chemistry (Lithium Manganese Dioxide) lasts slightly longer on low drain applications. It is hard to find the Lithium Manganese Dioxide cells in the UK/EU possibly due to environmental / transport regulations. |
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Re: File /8924C battery replacement.txt uploaded
#file-notice
I re-worked Ralph's great job, with a few edits and additions, into a PDF file.
/g/HP8924-Family-Spectrum-Analyzers/files/HP%208924C%20Memory%20Backup%20Battery%20Replacement.pdf |
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Re: File /8924C battery replacement.txt uploaded
#file-notice
That was a typo or something like that on my part Bob.? ?You are correct and Hank and I have been in contact and we worked it out.? I think he is going to correct it in the file for me.? Probably a few misspelled words also as I did not use a spell checker and my spelling is terrible.
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It should be a 0 instead of the 8.? The voltage is 3 volts.
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73 de Ralph ku4pt
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Re: File /8924C battery replacement.txt uploaded
#file-notice
Bob, Yes, that was a typo in the file which I just happened to have noticed earlier today.? Until I heard from Ralph, the file was edited to remove any reference to a D-K part number. Ralph bought the 270,? but there appear to be at least two other pin configuration variations by Panasonic that would also fit fine and available from D-K.? With parts shortages much more common these days, I think the file will soon reflect those options, and maybe have Mouser part numbers called out as well. Hank |
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Re: File /8924C battery replacement.txt uploaded
#file-notice
Digi key has the P278-ND battery as a 1.5 volt AAA size. Are you sure you did not mean a P270-ND, which is a non rechargeable BR-2/3 Lithium 3 volt cell?
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73, Bob, WX2NJ (Amateur) On 12/18/2021 3:42 PM, [email protected] Notification wrote:
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File /8924C battery replacement.txt uploaded
#file-notice
[email protected] Notification
The following files have been uploaded to the Files area of the [email protected] group. By: Ralph Mowery <ku4pt@...> Description: |
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File /Spectrum Analyzer Application Notes/an_1286-1.pdf uploaded
#file-notice
[email protected] Notification
The following files have been uploaded to the Files area of the [email protected] group. By: Larry McElhiney <lmcelhiney@...> |
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Added Folder /Spectrum Analyzer Application Notes
#file-notice
[email protected] Notification
Larry McElhiney <lmcelhiney@...> added folder /Spectrum Analyzer Application Notes |
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Re: 8924c memory loss
If anyone is digging into their test sets to replace weak or failing memory cells, please think of taking pictures of what you find and uploading them to the pictures section.? There's a scarcity of photos of that kind from the members and not much from HP either, even for just line drawings.
Hank |
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Re: 8924c memory loss
Important correction to an incorrect statement I made: In replying to Ralph's initial question about an 8924C, I brought up the notion of two AA cells used to retain data (and run the system clock).? It seems pretty certain now that none of the 8920 and 8924 test sets have these.? My? assuming that the 24C had these was incorrect.? Sorry for getting any 892x owners concerned about a memory battery that doesn't exist in their instruments. They are on some, maybe all, the 8935 series (both crt and electroluminescent display types) test sets.? One of these 8935s is pictured on the right side of our website and that's the one I have.? The AA battery is hidden behind the back plastic cover held on by six T15 Torx screws. This battery (one of two) is described in the big repair manual that was just uploaded November 7 in the HP 8935 directory.??Here's part of that section: ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?---------------------- Memory Backup AA Battery? Two battery sources are used to maintain the contents of the Test Set¡¯s memory when power is disrupted. One source is a set of two AA batteries mounted behind the rear frame of the Test Set. You must periodically change these batteries. The second battery source acts as a backup to the AA batteries. It is internally mounted and is not user serviceable.? CAUTION: Replace these batteries every 2-3 years. Failure to take prompt action may result in loss of RAM data including IBASIC programs and SAVE/RECALL states stored in the RAM. ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ??---------------------- ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? I think it would be a good thing for us to put together a FAQ that would provide specific details about the memory retention battery(ies) for as many of the 892X and 8935 series test sets as possible. Hank |
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Re: 8924c memory loss
The battery is only for the SRAM which holds? the power on settings for example? ?No calibration is impacted.
Calibration data is in the EEPROM on the processor board.? Usually a good idea to make a copy of that data.? That device is socketed since it needs to move over if the processor board is replaced. The biggest concern about corrupting? the alignment data in that EEPROM is for the RF Input assembly.? ?Some of the other assemblies have the calibration data on the assemblies themselves ( 8920B and 8924 ) using a small serial EEPROM Usually verify the RF Input? alignment data by jumpering the tracking gen out to the antenna in using the SA mode and the full 1Ghz span.? Should be pretty flat if the alignment data is intact and the RF input is working correctly.? +-4db flatness across the span should be good enough.? The level should match the tracking gen? output setting but if the average level is off that may be an SA? level adjustment.? ?Usually affects from 380-1000 Mhz with the varactor tuning used in that range if the EEPROM data is wrong. That step is done on top of the normal diagnostics before anything else is looked at. |
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Re: 8924c memory loss
that screw holds the bracket securing the PCMCIA socket.
On the 8920a/b there are two screws directly holding the memory card connector to the side of the chassis. Also the? 8920A early /mid versions use two of those batteries. Later versions of the 8920A and 8920B only use a single battery like the 8924 |
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Re: 8924c memory loss
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I ordered 3 of them as I have 3 of the 8924c units.? Shipping and all was only $23 for the 3 of them.? Shipping and tax was more than one battery.
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There was a battery place that popped up but they are about $ 9 each there.
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Wish you had mentioned that lone screw on the side.? Found it after 3 or 4 tries.? First try I had left the PCMCIA? card in, then 2 or 3 more tries and found that screw...
Battery shows about .7 volts.??
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73 and thanks again.
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Ralph
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Re: 8924c memory loss
THANKS very much.? I had pulled several of the other cards out that I though might have a battery? and did not think of that one having a battery.? Almost got an IC to replace on on a processor board,but looked it up and it did not seem to have a battery in it similar to the Dallas Clock type memory chips. I will look into ordering a couple as I have 3 of the 8924c that are about the same age for me.?? Only about a 'million ' screws in that thing .? I use a? battery powered drill to remove the ones I needed. Ralph ku4pt
On Sunday, December 12, 2021, 06:14:11 PM EST, jyelmgren <jyelmgren@...> wrote:
The SRAM battery has died on the PCMCIA /ROM/ memory card.? Far right hand side from the front ....lot's of screws though. The batteries are commonly available? ...the 8924 on used one of the 3v lithium solder in type ...DIgikey?P270-ND or?BATTERY LITHIUM 3V 2/3 A _._,_._,_ |
wx2nj
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