I need help to fix the HP 8640B freq. lock. ?
The output freq. wobbles greatly and will not hold onto any frequency as set by the cavity dial.
Any help would be appreciated.
I have downloaded some manuals, but no trouble shooting information was found.
Cheers, Steve Bell KJ7OG
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Thanks for the great replies! Some?have tried to identify the original part, but none of the parts matched exactly. The Avantek came closest, but these are apparently no longer available?with bandwidth?above 1300 MHz.
Some have offered possible substitutes, but they either do not have the bandwidth, or the pin outs are different from the OEM part. This makes me?suspect that the OEM part was truly a special part just for HP. The Keysight website offers no substitute, but marks the part as "obsolete".
So at this point, the best route is probably to acquire a modern MMIC and use a daughter board to connect to the original board holes. It should be fairly easy with the MIcrocircuit's amplifier. Except for the physical connections, the design, supporting parts, and supply voltage are very close to the original.
Thanks again for all of the great responses! I'll post again when I have a working solution.
Best regards,
Joe, KN5U
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I spent years hunting for one of these before I found one, so I just thought I¡¯d email this out in case anyone is looking for one. I don¡¯t know anything about the seller, but it looks like its in good shape.
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Re: Part Needed Ge Diode HP 1910-0016
Now I got curious and had to look at the schematic. It looks like almost any small-signal Ge diode or even a transistor junction would be a drop-in substitute. Looking at the parts list, it's clear that plenty of Si diodes were used elsewhere, while they used Ge in that spot, so one reason would be to get a lower forward voltage. Another possible reason is to somehow provide some degree of temperature compensation for the level detector diode, but it seems like a weird arrangement for that. The circuit demands aren't great - about 10 mA, forward biased, from R18 to -200V, without cathode current. It's not clear whether the diode is always supposed to be forward biased to set the Ks to slight negative voltage, or if it's a negative clamp to ground and normally the Ks should be a few V positive. If it's a clamp, then it doesn't seem necessary to use a Ge vs Si for the rest, so it seems more likely to set K voltage.
I took a quick look at the circuit description - nothing jumps out as obvious, but I think a thorough reading of it will tell you more about what's going on.
I'd say first try any diode you have on hand, and make some measurements to see the operating conditions. Alternatively, check the tube specs to see where the Ks should be at reasonable plate currents in this circuit - the Gs appear to work around ground to maybe a volt positive. After you've confirmed proper circuit operation, and found a Ge device substitute, you can return it to stock condition.
Ed
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Hi Joe,
I have GPD-402 and GPD-403. Tose guys can go till about 800MHz; for 402 gain drops from 14dB at 100MHZ to 12dB at 800MHz. For 403, 12dB at 100MHz to 8 at 800MHz.
But i think you need GPD-1001 or 1002 for go over 1GHz. All is specified at 15V supply.
Milan
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Re: Part Needed Ge Diode HP 1910-0016
This part is used in a HP 606B signal generator in the A4 oscillator
amplifier assembly.? It's in the cathode circuit of the differential
amplifier.? The differential amp provides a DC signal to the output
meter for each step of the output attenuator depending upon the
setting of a level control potentiometer.? I'm shaky on the the
operation of this circuit but it seems that this diode sets the
cathode bias on the 6AW8A differential amp.
David
KW4DH
On 2/23/2016 1:33 PM, edbreya@...
[hp_agilent_equipment] wrote:
?
What is the function of this diode in the circuit? If
it's just a rectifier or low speed signal diode, you
should be able to replace it with silicon easily, or with
a Shottky diode or rectifier if particularly low forward
voltage is needed.
Ed
--
The very essence of a free government consists in considering offices as public trusts,
bestowed for the good of the country, and not for the benefit of an individual or party.
John C. Calhoun 1835
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Re: Part Needed Ge Diode HP 1910-0016
What is the function of this diode in the circuit? If it's just a rectifier or low speed signal diode, you should be able to replace it with silicon easily, or with a Shottky diode or rectifier if particularly low forward voltage is needed.
Ed
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Part Needed Ge Diode HP 1910-0016
Is there a commercial/milspec equivalent for the HP 1910-0016 which is listed as a Ge diode 100mA/0.85V 60 PIV. Sphere has them @ $6 each, but the shipping from Canada is so expensive. This part is not listed in their cross reference of HP parts.
David
KW4DH
--
There are two possible outcomes: if the result confirms the hypothesis, then you've made a measurement.
If the result is contrary to the hypothesis, then you've made a discovery.
Enrico Fermi
--
The very essence of a free government consists in considering offices as public trusts,
bestowed for the good of the country, and not for the benefit of an individual or party.
John C. Calhoun 1835
|
Re: HP3585A repair of RAM board
On Tue, Feb 23, 2016 at 5:56 PM, multanova@... [hp_agilent_equipment] <hp_agilent_equipment@...> wrote:
I replaced both SN74S02N and SN7410N by new ones and everything went back to normal.
However strange.... suddenly 2 IC's dead together. I must say the boards were quite dusty
and perhaps it might be due to dust and moist that these died....that still puzzles me.
I don't know that particular schematic, but I always try to test logic ICs out of circuit after I remove them, to be sure I'm not missing something else bad into the board I'm repairing. Indeed a double fault is strange, unless for some reasons, the first fault caused the second. I once replaced a 7406 with a small hole in the case, all internal gates but two were still working :-) Best regards Frank IZ8DWF
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HP3585A repair of RAM board
Hi all readers,
Just wanted to inform that I have managed to repair my HP3585A 40 MHz spectrum analyzer? with :?
keyboard no reaction (all LEDS lit) and no display on CRT.
Following the manual Fault instruction tree to section C (processor and RAM /ROM debug). I had no signature analyzer nor extension boards, so not at all straightforward to?proceed. After some debugging with RAM and ROM boards removed, the processor board looked OK but? RAM refresh lines became dead after I reinserted the RAM board. Apparently some lines?
(clock and refresh LSTM) were shorted to earth by a malfunctioning input structure of a NOR?
gate.I could see with an oscilloscope that U35 and U36 (RAM board) were completely dead and the? gate outputs were at approx. 2.5V iso pulsing between 0 or 5V.
I replaced both SN74S02N and SN7410N by new ones and everything went back to normal.
However strange.... suddenly 2 IC's dead together. I must say the boards were quite dusty? and perhaps it might be due to dust and moist that these died....that still puzzles me.
Now I get a CAL error 28 however I have a small error in amplitude only. So I will proceed? to solve this. Possibly some contact resistance increase in one of the input attenuator?
relays but clearly a minor issue....
Only to say that one better not give up too early on a complex malfunctioning and a ? signature analyzer and extension ?boards are not always necessary. Guess my HP3585A is ?
quite an early model (no 1750A00558) from end of the seventies...however the CRT is still in great condition.
Of course I was lucky none of the critical components such as the uP or ROM's were?damaged.
I am quite happy I got this magnificent instrument back to work.
regards? from Felix
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A small OT hint: The same goes for the output amplifier in the old 8640B. I replaced that one with a MiniCircuit MMIC. Had to disconnect the +40V and use an external voltage regulator though. Just watch up for PSU ripple.
Ulf - SM6GXV
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Maybe more suitable NEC UPC1654 but still rolls off rapidly above 1.1GHz. You could try your luck with recently discussed China sourced products. :(
Dennis
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On Tue, 2/23/16, g4gjl@... [hp_agilent_equipment] <hp_agilent_equipment@...> wrote:
Subject: Re: [hp_agilent_equipment] Re: Part Needed
To: hp_agilent_equipment@...
Date: Tuesday, February 23, 2016, 11:19 AM
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I believe this device is a GPD from the AVANTEK range in the
late 1970s and early 80s.?
See datasheet at:
?
There were three and four pin
devices made as the datasheet shows. Does this help in
identifying the device?
PeteG4GJL
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Re: 8594e front panel buttons not responding
IIRC, the 859x series uses the rubber membrane style keyboard, Peter.? I¡¯m still betting on a disconnect at the keyboard end.? At least most of the keyboards are fairly easy to access. ? Daun ? Daun E. Yeagley, II, N8ASB ?
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From: hp_agilent_equipment@... [mailto:hp_agilent_equipment@...]
Sent: Tuesday, February 23, 2016 11:34 AM
To: hp_agilent_equipment@...
Subject: RE: [hp_agilent_equipment] Re: 8594e front panel buttons not responding? ? I assume you checked the power supplies with a ¡®scope? I have some spare buttons and springs for other front panels. I will check, contact me off line. PeterB ? ? ? From the manual, hitting [CONFIG] [(LOCAL)] should bring it back to local if it's it remote mode, and [CONFIG] does nothing, so I don't think that's it.
I think Daun is correct, the keyboard is defective or disconnected.? The cable seems intact at the CPU end, so now I'll have to disassemble the front panel.
Dave
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Re: 8594e front panel buttons not responding
I assume you checked the power supplies with a ¡®scope? I have some spare buttons and springs for other front panels. I will check, contact me off line. PeterB ?
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From: hp_agilent_equipment@... [mailto:hp_agilent_equipment@...]
Sent: February-23-16 11:24 AM
To: hp_agilent_equipment@...
Subject: [hp_agilent_equipment] Re: 8594e front panel buttons not responding? ? From the manual, hitting [CONFIG] [(LOCAL)] should bring it back to local if it's it remote mode, and [CONFIG] does nothing, so I don't think that's it.
I think Daun is correct, the keyboard is defective or disconnected.? The cable seems intact at the CPU end, so now I'll have to disassemble the front panel.
Dave
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Re: 8594e front panel buttons not responding
From the manual, hitting [CONFIG] [(LOCAL)] should bring it back to local if it's it remote mode, and [CONFIG] does nothing, so I don't think that's it.
I think Daun is correct, the keyboard is defective or disconnected.? The cable seems intact at the CPU end, so now I'll have to disassemble the front panel.
Dave
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I believe this device is a GPD from the AVANTEK range in the late 1970s and early 80s.?
See datasheet at: ?http://www.rf-microwave.com/en/shop/0/393-high-performances-professional-mmic/4168-GPD-401.html
There were three and four pin devices made as the datasheet shows. Does this help in identifying the device?
Pete G4GJL
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Re: 8594e front panel buttons not responding
Part of the IEE-488 standard was a function called ¡°local lock out¡±? (LLO) which does prevent local operation or even going to local (GTO), but I don¡¯t recall that it survives a power cycle. ? Daun ? ? ? Daun E. Yeagley, II, N8ASB ?
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From: hp_agilent_equipment@... [mailto:hp_agilent_equipment@...]
Sent: Tuesday, February 23, 2016 10:40 AM
To: hp_agilent_equipment@...
Subject: [hp_agilent_equipment] Re: 8594e front panel buttons not responding? ? From memory, doesn't this thing have a 'Hold' function key that locks out the keys, keypad and encoder knob? It hasn't got stuck in that mode somehow has it?
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HP 8355X mm wave module with HP 8673B/C/D signal generator
Hi,
The HP 8355X millimeter-wave source module is used with an HP 8673B/C/D signal generator and an HP 8349B amplifier to generate mm wave signals. The manual notes that the 8355X requires the signal generator to have an output of 0.5V / GHz. The manual also notes that early models of these signal generate 1V / GHz and they must be modified with a retrofit kit to change this to 0.5V / GHz. For example, the retrofit kit for the 8673B is P/N 08673-60130.
As I assume these retrofit kits are not available, does anyone know details of what they contain and how they are to be installed?
Thanks!
Ray VE3FN
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Hi David,
I was able to review the MAR-3+ MMIC datasheet, and I believe that I may need an add-on board. I posted some pictures of the 5335A A9 board, especially in the vicinity of the U1 amplifier IC. See album "".
The existing four-pin configuration that I mentioned earlier in this string is actually a thru-hole bottom arrangement. I will need to adapt from the Minicircuit's surface mount arrangement to the thru-hole arrangement. I can?build a prototype board to do this.
The original attachment was solderless, using the plug-in holes on the circuit board in conjunction with mechanical flanges, screws, and nuts?to hold the IC tight to the board. I will likely need to solder the four pins with the new configuration.
I am relatively new at SMT, so any comments or suggestions would be very helpful.
Thanks,
Joe / KN5U
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Re: 8594e front panel buttons not responding
From memory, doesn't this thing have a 'Hold' function key that locks out the keys, keypad and encoder knob? It hasn't got stuck in that mode somehow has it?
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Pete_G4GJL