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Loading 8340 FW into a 8341 sweeper
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This may sounds crazy but have anyone tried to put the 8340 CPU board into a 8341 or just the FW prom? I looked through a lot of the schematics and comparing the part numbers for major assemblies, they look extremely similar. The 8341 level control logic also has the 20Ghz breakout support just like 8340 does. Although 8341 has a 20Ghz SYTM and 8340 has a 26.5g one, but the SYTM driver and control logic assemblies are identical. I'm sure there will be some differences in the CPU boards (FW ROM) that disables band 4 in 8341. I am curious if a 8341 SYTM can be overdriven to send out 26.5ghz at usable output level if the CPU board allows it? Based on my previous experience with SRD, n and n+1 harmonics are pretty comparable in amplitude, and having YIG filter march up couple gigs is not impossible. Thanks, Calvin |
开云体育
Hi there it is much easiere just take the caibration letter inside the unit and look for the line with the model number. Simply enter the 8340 in there and you have a 26.5Ghz generator. It might have a few dbm lower output as the SYTM is not calibrated upthere. You?can look in the manual how to change the values in the EEprom through the buttons on the front panel. best regards Peter Fra: hp_agilent_equipment@... p? vegne af guancalvin@... [hp_agilent_equipment]
Sendt: 24. oktober 2017 23:45
Til: hp_agilent_equipment@... Emne: [hp_agilent_equipment] Loading 8340 FW into a 8341 sweeper ?
?
This may sounds crazy but have anyone tried to put the 8340 CPU board into a 8341 or just the FW prom? I looked through a lot of the schematics and comparing the part numbers for major assemblies, they look extremely similar. The 8341 level control logic also has the 20Ghz breakout support just like 8340 does.
Although 8341 has a 20Ghz SYTM and 8340 has a 26.5g one, but the SYTM driver and control logic assemblies are identical.
I'm sure there will be some differences in the CPU boards (FW ROM) that disables band 4 in 8341. I am curious if a 8341 SYTM can be overdriven to send out 26.5ghz at usable output level if the CPU board allows it? Based on my previous experience with SRD, n and n+1 harmonics are pretty comparable in amplitude, and having YIG filter march up couple gigs is not impossible.
Thanks, Calvin |
开云体育Hey, which correction constant is it?this is really cool :-)
So are the 8340's just selected 8341's?
Or is there some other difference between the models?
Tobias
-------- Original message --------
From: "Peter Hansen oz1lpr@... [hp_agilent_equipment]"
Date: 10/25/17 00:11 (GMT+01:00)
To: hp_agilent_equipment@...
Subject: Sv: [hp_agilent_equipment] Loading 8340 FW into a 8341 sweeper
?
Hi there it is much easiere just take the caibration letter inside the unit and look for the line with the model number. Simply enter the 8340 in there and you have a 26.5Ghz generator. It might have a few dbm lower output as the SYTM is not calibrated upthere. You?can look in the manual how to change the values in the EEprom through the buttons on the front panel. best regards Peter Fra: hp_agilent_equipment@... p? vegne af guancalvin@... [hp_agilent_equipment]
Sendt: 24. oktober 2017 23:45 Til: hp_agilent_equipment@... Emne: [hp_agilent_equipment] Loading 8340 FW into a 8341 sweeper ?
?
This may sounds crazy but have anyone tried to put the 8340 CPU board into a 8341 or just the FW prom? I looked through a lot of the schematics and comparing the part numbers for major assemblies, they look extremely similar. The 8341 level control logic also has the 20Ghz breakout support just like 8340 does.
Although 8341 has a 20Ghz SYTM and 8340 has a 26.5g one, but the SYTM driver and control logic assemblies are identical.
I'm sure there will be some differences in the CPU boards (FW ROM) that disables band 4 in 8341. I am curious if a 8341 SYTM can be overdriven to send out 26.5ghz at usable output level if the CPU board allows it? Based on my previous experience with SRD, n and n+1 harmonics are pretty comparable in amplitude, and having YIG filter march up couple gigs is not impossible.
Thanks, Calvin |
开云体育Hi Tobias,
Instr. Preset Sh GHz??? 1 Hz Sh MHz 12 Hz Sh kHz 22 Hz enter Value Press Hz Zum ???ndern des Frequenzbereichs: Sh GHz 54 Hz Sh MHz 12 Hz Sh kHz 22 Hz 20000 -> 26500 Hz to Store: Sh MHz?????? 14 Hz Sh kHz 5349 Hz Instr. Preset mfg, Rainer Am 25.10.2017 um 07:16 schrieb Tobias Pluess tobias.pluess@... [hp_agilent_equipment]: ??? |
开云体育The service manual lists different part numbers for some assemblies.The YTO is one. Possibly there were enough YTOs that did not meet spec for the 8340 that the 8341 was built to use these parts that did not pass for the 8340. There would have been sufficient market for the reduced frequency range. The US military bought a number of 8340s with the same coverage as the 8341 and with a type N connector for output. This 8340 had a mod number and could possibly be made a fully functional 8340 by changing the connector and calibration constants. I suspect that the 8341 will not function to specification if calibration constants were entered for the range of the 8340. This is my opinion based on the technical manuals and a very little knowlege of how products are brought to market. Glenn On 10/25/2017 1:16 AM, Tobias Pluess
tobias.pluess@... [hp_agilent_equipment] wrote:
Hey, which correction constant is it? -- ----------------------------------------------------------------------- Glenn Little ETCS(SS) USN Ret, ARRL Technical Specialist, SBE ARRL TAPR Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178 QTH: Goose Creek, SC USA (EM92xx) USSVI, FRA, NRA LM QCWA LM 28417 "It is not the class of license that the Amateur holds but the class of the Amateur that holds the license" --------------------------------------------------------------------------- |
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Hello all,
I'd have to say its most certainly possible. Even an A model can turn into or rather be upgraded to a B model. Just gotta find the right parts which isn't much. You could even make them too! (say create your own assembly board, bias board, or drill a hole that is missing like the FM input). Also if you have the time, that helps too. ;) As for YTOs I wouldn't sweat it too much. They are easily swappable despite different part numbers. I'd pick the higher number of the 2 of course, since the higher one is newer with improvements for that time. Another keyword is for that time. It is even possible to take a YTO from a completely different instrument and just stick it in this unit if the donor unit was made around the same time as this unit. You may have to redesign the bias PCB on top though. While its true you could create a secondary market with something that has less bandwidth, another point is that redesigning parts then manufacturing them again costs lots of money. Companies don't like waste money so they'll turn up the same design with some minor improvement. Maybe add some extra marketing wank along the way. Recent case of "within model series" (8560X series; X= A, B, E or EC) is when I swapped a 5086-7781 for a 5086-7906 in a 8561B to a 8563E's. The only difference I saw between the 2 YTOs was a "purge port" that was added then later deleted possibily because its not needed. The hybrid circuit, YIG ball, overall physical dimensions, and even the bias PCB on top outside remained the same. However don't get too eager with converting same models of units. I currently can't convert a 8561E to a 8563E. Mainly because the RF and Frequency boards are very different and are not cheap to make or buy yet. Plus you'd have to screw around with the ROM to read 8563E instead of 8561E (if you want the higher model). If there are people willing to desolder their ROMs for reading and post the results, this would be great. Very recently I have found a case for obtaining parts for dissimilar units. Rather they are marketed as such. I've found out that the same hybrid circuit "block", which I thought was unobtainium at first, is used in 4 different units or at least marketed as different units. 2 of them are analyzers and 2 of them are generators. The generators are of different model numbers while the analyzers are marketed for different measurements. Currently I'm in the delicate process of obtaining a part or 2 from something that is "really trashed" so I can't disclose exactly what are the model numbers but if there is a HP engineer in Microwave ICs from the 80s and 90s amongst us, they'll confirm what I am saying. I also detest destroying a perfectly repairable unit just to get 1 part out of it. Then of course for sure you can find that hard to find IC like that datel in the other thread and check if any other different piece of kit or board uses the same IC. I'd say ~9 of 10 this is where I get my pulls from. The parts list in service manuals are fountains of info for this purpose. If lucky enough, perhaps you could even google "part number .pdf" and a few hits turn up if someone mirrors the same pdf (like some testequipmentsales site or even here). Overall, if one is willing to spend time and effort moving mountains and the heavens then it is possible. Things like google and search engines in general have made this journey way too easy than in the past. For that I thank the people who were nice enough to provide the data or set up such search functions. You can even make this journey for pennies if you're creative enough. Can never really say "can't be done". There is always a way. -Lex |
开云体育Hi GuysI also tried to retrofit my 8341A to an 8340A. It works, kind of - I could actually set the frequency to 26.5GHz and I saw the signal on the spectrum analyzer.
However, leveling was completely crappy and didn't work properly above approx. 22GHz, so, I retrofitted my unit back to the 8341A it was before. However, I think the ALC could probably be calibrated, but I cannot do that unfortunately because I don't have
that frequency response test set or storage normalizer which is required to test and adjust the ALC (I don't even know what a frequency response test set is, but sounds like a VNA).
I tested the 8341A flatness using CW mode and documented my results here
https://hb9fsx.ch/wordpress/index.php/2017/10/13/hp-8341a-repair-part-iii/
in the 'update' section (scroll down). When I activated the 26.5GHz operation, behaviour over 22GHz was much worse than these results.
(any ideas how that unit can be calibrated without using a storage normalizer and all this stuff?).
Tobias
-------- Original message --------
From: "rastr0@... [hp_agilent_equipment]"
Date: 10/25/17 18:37 (GMT+01:00)
To: hp_agilent_equipment@...
Subject: [hp_agilent_equipment] Re: Loading 8340 FW into a 8341 sweeper
?
Calvin, |