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Re: HP8924C duplexer tuning setup
Found right here: HP 8920A Application Handbook? ? HP 8920B Application Handbook? ___________________________________________________________
On Tuesday, July 30, 2024 at 12:30:11 PM EDT, Mike wrote:
The HP 8920A Application Handbook has a section on passive cavity and return loss measurement, the 8924 should be similar in setup.
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https://www.keysight.com/us/en/assets/9018-40358/reference-guides/9018-40358.pdf |
Re: HP8924C duplexer tuning setup
Here is another excellent video from Brian Swann on duplexer tuning using a very similar test set made by HP. Best of luck. Pete
On Tuesday, July 30, 2024 at 09:10:34 AM CST, Andy <akunik@...> wrote:
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Here is a good youtube video describing the process. If you do a youtube search you will find many more examples.
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HP8924C duplexer tuning setup
I have one of those small UHF duplexers, and I think I need to tune it up.
I took the ARES group's portable UHF repeater out yesterday and most of the time the repeater would receive my signal and transmit a carrier and courtesy tone at distance. But I would not hear my audio out until I was only a few blocks away. Where can I find the best documentation for how to set up the HP8924C tracking gen and see/adjust the nulls on the duplexer TX & RX sides? ?
Thanks folks.
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Mark Weisenfeld K7TUM * |
WORKING HP 8924C Test Set on eBay
Caution:? I just found this listing by accident.? I know nothing about the seller or their reputation.? Just passing on the info because right now the price is good if all functions are working and there is good calibration.? I'm sure the price will rise sharply, but might still be good, esp. for local pickup or for a buyer near Florida. US $155.50 ? (as of 4:15 PM EDT Wednesday; 4 bids)Ends?Thursday, 07:16 AM Eastern Daylight Time Pickup: Free local pickup from Clearwater, Florida, United States 33763 USPS Ground Shipping to US; depends on distance; mininum charge looks to be about $76 (Florida destination) _______________________________________________________________ |
Re: HP 8935 has false alarm for overvoltage duplex out
opened the I/O module on the underside next to the I/O panel.
What are the silk screen number (s) for the detection? diodes?
I see some of tht SOT23 packages labeled CR1 to 4 and cr200 and cr201.
I sure wish schematics were available for this thing! |
HP 8924C For Sale
Unit is in working condition. I opened it up to see if there were any power supply (swollen caps) issues and everything looks good to go. The screen does appear to have a slight "burn in (see photo) but functions fine. Comes with a power cord. Looking for the best "reasonable" offer. I am sure it would benefit someone that utilizes this test set more than I (I have another, smaller unit). Rather not throw it up on eBay if at all possible. Take care!!
P.S. The location of this unit is in Clearwater, Fl.? Edit 7-18-2024 This test set is now on eBay with added local pickup option
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Re: HP8924C Memory cards for calibration data in 2024
Thanks Robert,
Rab at Amtronix did offer me a lifeline so I'll check in with him tomorrow. Still, making the disk drive work and learning about how the Cal program is written has been fun and educational. I think I've correctly modified the program to access the disk instead of the card but I have an iBasic error with a file name to figure out. Jim. |
Re: HP8924C Memory cards for calibration data in 2024
From direct personal experience with these things. 2/ The cards are accessed in "linear" mode ie addressed like RAM or ROM. 3/ They will READ any type of PCMCIA card, but will only WRITE to RAM or SRAM cards. 4/ PCMCIA to SD card adaptors WILL NOT WORK 5/ SOME PCMCIA to CF Adaptors will work but not many. They need to support linear mode, most only work in IDE mode i.e. like? HDD not ROM. |
Re: HP8924C Memory cards for calibration data in 2024
Hi Rab,
thanks for joining in! For my HP859x analyzers I have 2 of the 40 pin Epson cards but alas, no 68 pin SRAM PCMCIA cards. Just the other day I called Amtronix! I have a friend who bought three of your 60 watt kits for the 8924C about 13 years ago. However, he had labeled his PCMCIA card as "100 Watt" and that created some confusion when we tried to resurrect one of his older 8924C instruments. The installed attenuator was actually 14dB and not 20dB so all of our readings were shy by 6dB. Learning about all of details of the upgrade inspired me to have a go at upgrading my own 8924C. Jim |
Re: HP8924C Memory cards for calibration data in 2024
Well, I've hit a snag with the disk scheme. I did receive my 3.5" drive with the USB connection. It runs fine on Windows 11 and I was able to drop the Cal files onto the floppy that I was able to store instrument config files into. So all is good with creating floppies to put into the HPIB disk drive.
This is where the fun starts because I knew nothing of HP iBasic before this and am learning on the fly. The attenuator cal files we have are built for storage in and use from the HP SRAM card. Not a deal killer because I am slowly learning what to change to make them compatible with the HPIB disk drive. For instance, I believe the original DwnldCal0.PRC process file needs to be modified or replaced and in the TESTS main menu in the bottom area there is a SAVE/DELETE PROCEDURE tool that I am still figuring out. I'm not sure how else to edit the original PRC so I think a new one has to be created. The DNLDCAL4.PGM file is not even needed. It's used for 8935 and 8285A instruments. The DNLDCAL0.PGM file needs to be modified from calling for the SRAM card to calling the disk. The line looks like this as it defines what memory storage is to be used: ????? MASS STORAGE IS ":INTERNAL,4" ? ? ? ? ? ? ?Replace ":INTERNAL,4"? with ":,700,0" which is the value I mentioned earlier for the disk drive. The value can be found in the TESTS menu at the bottom with the COMMAND entry called Cnfg EXTERNAL DEVICES Anyone that knows more than I do please chime in!! Jim |
Re: HP8924C Memory cards for calibration data in 2024
CrazyFin & Lorenzo
Thank you very much for your feedback! Here are some of the things that I ran across during my searches. I did read that dalton.ax page and there are some similar efforts at disk drive emulators such as this Arduino project There are a number of Arduino based HPIB to USB projects out there. I've seen a few videos but didn't pursue those avenues of thought yet. This HP Museum page has some useful docs on HP disk drives ? There are some Epson adapter cards out there which could have flash memory cards or SD cards plugged in. I don't know if the 8924C will be able to properly address such large memory arrays. A number of automobiles used such cards and I also saw that CNC machining systems used PCMCIA cards and used prices on the cards are similarly crazy. There are groups for the HP85 and HP87 computers that have useful resources for dealing with HPIB and peripherals. My disk drive was made by a Japanese company, ISA Quality Products, Model 1015. It is not HP labeled but is almost identical to some HP dual drives. The HPIB dip switches on the back have no labeling so it was a guessing game to have it set to address 0 to match the 8924C's field for External Disk Specification. I've yet to find if I have the manual somewhere or if it is long gone. Web searches have not yet borne fruit. From memory, some other HPIB setting notes for the 8924C and a disk drive. On the I/O configure screen initially set MODE to Control and Save/Recall to Disk. Go to the TESTS screen and scroll to the area SET UP TEST SET. Scroll to Cnfg: External Devices.(Select) At the bottom check External Disk Specification to read? ? :,700, 0 ?? as this is having the 8924C look on the HPIB for a peripheral with address set to 0 I have a precious old XP laptop, a Dell Latitude D600 that has the correct PCMCIA slot so I'll have to experiment with programming any cards that I can (if ever) acquire. A bit more background to what is driving all of this. A friend had said that he had an HP PCMCIA card with the 100W Cal files loaded on it so we attempted to load them and they seemed to go in. However, power readings were off. Eventually I realized that readings were always off by 6dB and slowly realized that his card had a cal file for the 60W 14dB attenuator and not the 20 dB attenuator that I have installed. Yikes. He is afraid to try to modify his card so it leaves me to go to square one and come up with a way to get the proper 20dB file into my 8924C. One other hiccup. I think in loading his card something with my options has been messed up. A number of weeks back I had set up the 8924C analog screens where I wanted them to initialize at power up and stored those in the POWERON file. Now if I attempt to invoke POWERON manually I get a worrisome message "Options present at Save are missing" Jim |
Re: HP8924C Memory cards for calibration data in 2024
Gents, are you aware of this cool project called "GPIB / HP disk emulator"? |
Re: HP8924C Memory cards for calibration data in 2024
Jim, I was able years back to use an old laptop with a PCMCIA slot for writing to two PCMCIA cards, you want to look for the Mitsubishi MELCARD models. This could work with PCI adapters for PCMCIA too, and some fiddling. Ultimately though you will need some command line shenanigans to mount, configure and format the filesystem (msdos/FAT16 if I remember right). It isn't too complicated but it is indeed a chore to get the legacy tech cooperating with modern equipment. Other users of these cards include audio techs and musicians with legacy gear, Amiga 600/1200, some old CNC systems... You might be able to use Windows XP as well: Expect prices to be extremely inflated, as you have seen. Honestly I would expect some form of emulator to be available somewhere from the retro computing folks. The other possibility is remoting the HP kit to write to the card. I think SRAM cards won't be a reliable option anymore, both due to the price inflation, failures (the cards usually need an internal battery to keep the data, at some point they will fail), etc. The GPIB based drive emulators seem like a great option. Not a good idea to spend much on the SRAM options, and I would advise against buying a reader for them (from Amtron for example) unless your day job is literally working with legacy test gear.
Cheers
On Thursday, June 20th, 2024 at 2:57 AM, Jim via groups.io <teotwaki@...> wrote: I am still interested in the memory cards but I may have come up with a workaround. |
Re: HP8924C Memory cards for calibration data in 2024
I am still interested in the memory cards but I may have come up with a workaround.
A long time ago, my HP8722C had come with a new HPIB dual 3.5" floppy drive that I had forgotten about. It was still new in the box, stored in the garage. After a lot of reading and trying settings I now have the 8924 talking to the drive and have been able to successfully store and recall the current instrument test states for Rx and Tx. I've ordered a USB to 3.5" floppy drive on Amazon and hope to have it tomorrow. I plan to put the cal files onto a floppy and then recall them into the 8924. Jim |