Re: Adjustment procedure for 355C VHF Attenuator?
Jared: Have many 355C and D, excellent attenuators.
But your readings are so close, the range of error of your setup and instruments will be an issue. EG how close is your source and termination to 50 .000 Ohms?
Simple DC test:
Get a precision stable DC refences, and exact 50.00 Ohm R for source and term, eg 1.000 V ,(watch dissipation!) place 4.5..6.5 digit DVM at input and output, get ratios.
As the resistors are very wideband you may do more harm than good to "trim" or adjust!
"if it isn't broke don't fix it!"
Jon
Kind Regards,
Jon
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Re: Adjustment procedure for 355C VHF Attenuator?
The only way that I know of is to replace the resistors. One thing to keep in mind is that the readings will be different at higher frequencies, due to capacitance and inductance of the resistor networks. From your tests, it looks like some of the switches are not working properly. For instance, 9dB uses the 6dB and 3dB in series. You show no error for 6dB and 9dB, yet 3db is out of spec. I would try rotating the selector a few dozen times, then retest. You may need to replace those switches. The cams may be worn a bit. Is there any adjustment to the switch position? I have some of these, but they are boxed up right now.
On Sun, Feb 6, 2022 at 12:47 AM Jared Cabot via <jaredcabot= [email protected]> wrote: Hi all,
I recently picked up a 355C VHF Attenuator for a cheap price that I was able to repair by cleaning the cam section to allow the mechanism to press on the micro switches reliably (a little corrosion on the aluminium casting was binding up the works).
Now, I do know enough to leave the other parts well enough alone, no touching of the metal plates that form the gimmick capacitors used for trimming the unit into spec, etc.
However, after testing the ranges at 1kHz (all I've done so far, still repairing my function gen capable of 500MHz and 1GHz) I have found some ranges are out of spec.
Here are the results:
dB Set??? Measured dB??? dB Difference (spec = 0.1dB@1kHz)
0??? ??? ?? - ??? ?? 11.97??? ??? -??? ??? -0.03dB
1??? ?????? -??? ??? 10.94??? ??? -??? ??? -0.06dB
2?????????? -??? ??? 9.87??? ? ? ? -??? ??? -0.13dB
3?????? ??? -??? ??? 8.86?? ?? ??? -??? ??? -0.14dB
4??? ?????? -??? ??? 7.85??? ?? ?? -??? ??? -0.15dB
5?????????? -??? ??? 6.81??? ?? ?? -??? ??? -0.19dB
6?????????? -??? ??? 6.00??? ?? ?? -??? ???? 0.00dB
7?????????? -??? ??? 5.02??? ?? ?? -??? ??? +0.02dB
8?????????? -??? ??? 3.99??? ?? ?? -??? ??? -0.01dB
9?????????? -??? ??? 3.00??? ?? ?? -??? ???? 0.00dB
10???????? -??? ??? 2.01??? ?? ?? -??? ??? +0.01dB
11???????? -??? ??? 0.99??? ?? ?? -??? ??? -0.01dB
12???????? -??? ? ? 0.00??? ?? ?? -??? ??? Reference setting
You can see that settings 2, 3, 4, and 5 are out of spec.
Now my question... Does anyone know if the adjustment procedure was ever released by HPAK? Or has anyone figured it out?
I have this device working quite well apart from those few settings reading too low and I got this device very cheap, so I'm not averse to a bit of guided tweaking.
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Adjustment procedure for 355C VHF Attenuator?
Hi all,
I recently picked up a 355C VHF Attenuator for a cheap price that I was able to repair by cleaning the cam section to allow the mechanism to press on the micro switches reliably (a little corrosion on the aluminium casting was binding up the works).
Now, I do know enough to leave the other parts well enough alone, no touching of the metal plates that form the gimmick capacitors used for trimming the unit into spec, etc.
However, after testing the ranges at 1kHz (all I've done so far, still repairing my function gen capable of 500MHz and 1GHz) I have found some ranges are out of spec.
Here are the results:
dB Set??? Measured dB??? dB Difference (spec = 0.1dB@1kHz)
0??? ??? ?? - ??? ?? 11.97??? ??? -??? ??? -0.03dB
1??? ?????? -??? ??? 10.94??? ??? -??? ??? -0.06dB
2?????????? -??? ??? 9.87??? ? ? ? -??? ??? -0.13dB
3?????? ??? -??? ??? 8.86?? ?? ??? -??? ??? -0.14dB
4??? ?????? -??? ??? 7.85??? ?? ?? -??? ??? -0.15dB
5?????????? -??? ??? 6.81??? ?? ?? -??? ??? -0.19dB
6?????????? -??? ??? 6.00??? ?? ?? -??? ???? 0.00dB
7?????????? -??? ??? 5.02??? ?? ?? -??? ??? +0.02dB
8?????????? -??? ??? 3.99??? ?? ?? -??? ??? -0.01dB
9?????????? -??? ??? 3.00??? ?? ?? -??? ???? 0.00dB
10???????? -??? ??? 2.01??? ?? ?? -??? ??? +0.01dB
11???????? -??? ??? 0.99??? ?? ?? -??? ??? -0.01dB
12???????? -??? ? ? 0.00??? ?? ?? -??? ??? Reference setting
You can see that settings 2, 3, 4, and 5 are out of spec.
Now my question... Does anyone know if the adjustment procedure was ever released by HPAK? Or has anyone figured it out?
I have this device working quite well apart from those few settings reading too low and I got this device very cheap, so I'm not averse to a bit of guided tweaking.
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Re: 8596E cal: not stored
To be clear, there's the "calibration data" which is the result of the unit's self-cal routines, and then there's the "correction constants" which is the characterization of the attenuator, reference oscillator, etc. that's performed using external equipment.? Both sets of numbers are stored in the battery backed SRAM.
The calibration data is regenerated when the self-cal is run, but without accurate correction constants the unit will not meet its specifications.? If you're battery was dead when you received the unit, you've unfortunately lost your correction constants.? But if you're saying the attenuator was already in need of replacement, you would need to regenerate the correction constants anyway.
Regenerating the correction constants is covered in Section 2 of the Assembly-Level repair manual.
The supercap was probably ok.? It's only there to keep the SRAM running for a few hours while you change the battery.
-mark
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Re: 8596E cal: not stored
On Sat, Feb 5, 2022 at 01:04 PM, Franco Macci¨° wrote:
Taken on ebay with battery and 0 volt supercap, even the attenuator is broken, it does not complete the amplitude calibration I think for this reason, I will have to replace it with a new one, I hope that afterwards it will be able to perform the two cals and be able to store the data calibration.
---- In the service manual it tells how to record current calibration constants, most likely you will see random data there. Still worth recording. Section 3 of the service manual describes what to do when calibration constants are not valid. I didn't need this step, I recorded constants before battery replacement and didn't lose data, so no firsthand experience. You need to start with something ballpark right to continue with the auto-cal steps.? Ozan
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Re: 8596E cal: not stored
Taken on ebay with battery and 0 volt supercap, even the attenuator is broken, it does not complete the amplitude calibration I think for this reason, I will have to replace it with a new one, I hope that afterwards it will be able to perform the two cals and be able to store the data calibration.
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I would like a copy also, please.
Bob K6DDX
On Saturday, February 5, 2022, 12:53:04 PM PST, N5ZTW via groups.io <n5ztw@...> wrote:
Thank you and yes I would like a copy of the service manual schematic please
Bill
On Jan 31, 2022, at 1:21 PM, sv1aku via groups.io <sv1aku@...> wrote:
Hi Bill,
see attached PSU schematic I got from a guy back in 2009 when I was trying to repair my HP 54501. I also have the 54501 schematic in PDF ( from 90903 service manual supplement)? if anybody ever? needs it.
Thanks,
Konstantinos SV1GSI
¦²¦Ó¦É? ¦¤¦Å¦Ô¦Ó?¦Ñ¦Á 31 ¦©¦Á¦Í¦Ï¦Ô¦Á¦Ñ?¦Ï¦Ô 2022, 07:28:12 ¦Ì.¦Ì. EET, ¦Ï ¦Ö¦Ñ?¦Ò¦Ó¦Ç? N5ZTW via groups.io <n5ztw@...> ?¦Ã¦Ñ¦Á¦×¦Å:
Howdy friends, I have a pair of 54503A scopes. Both had the dreaded Dallas semi Battery ram chip go bad.
I purchased a new Dallas unit and pulled the bad installed a socket and the new unit. Now The system will not boot I have garbage on the screen.
Pretty sure I must have broken an interconnect via while removing the old unit. (it did not come out as easy as I had hoped)
I have discovered the schematics for this unit are some kind of top secret as I simply can't find them. I read somewhere there is a former HP tech who works on these. Does anyone have contact information? I would like to send the main board for repair to this person if it can be done for a reasonable fee.
One unit has a bad PSU which is a poor design with the caps up against heatsinks. I replaced the puffed up caps but it looks like the bad caps took out a FET. Thanks to the member who did some reverse engineering? and provided notes I should be able to repair. In the long run I hope to simply get one to the point where I don't have to do the entire cal procedure every time I want to use it.
Thanks, Bill N5ZTW .
<supplyHP54503.pdf>
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Thank you and yes I would like a copy of the service manual schematic please
Bill
On Jan 31, 2022, at 1:21 PM, sv1aku via groups.io <sv1aku@...> wrote:
Hi Bill,
see attached PSU schematic I got from a guy back in 2009 when I was trying to repair my HP 54501. I also have the 54501 schematic in PDF ( from 90903 service manual supplement)? if anybody ever? needs it.
Thanks,
Konstantinos SV1GSI
¦²¦Ó¦É? ¦¤¦Å¦Ô¦Ó?¦Ñ¦Á 31 ¦©¦Á¦Í¦Ï¦Ô¦Á¦Ñ?¦Ï¦Ô 2022, 07:28:12 ¦Ì.¦Ì. EET, ¦Ï ¦Ö¦Ñ?¦Ò¦Ó¦Ç? N5ZTW via groups.io <n5ztw@...> ?¦Ã¦Ñ¦Á¦×¦Å:
Howdy friends, I have a pair of 54503A scopes. Both had the dreaded Dallas semi Battery ram chip go bad.
I purchased a new Dallas unit and pulled the bad installed a socket and the new unit. Now The system will not boot I have garbage on the screen.
Pretty sure I must have broken an interconnect via while removing the old unit. (it did not come out as easy as I had hoped)
I have discovered the schematics for this unit are some kind of top secret as I simply can't find them. I read somewhere there is a former HP tech who works on these. Does anyone have contact information? I would like to send the main board for repair to this person if it can be done for a reasonable fee.
One unit has a bad PSU which is a poor design with the caps up against heatsinks. I replaced the puffed up caps but it looks like the bad caps took out a FET. Thanks to the member who did some reverse engineering? and provided notes I should be able to repair. In the long run I hope to simply get one to the point where I don't have to do the entire cal procedure every time I want to use it.
Thanks, Bill N5ZTW .
<supplyHP54503.pdf>
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Re: 8596E cal: not stored
The manual says that error will occur if there aren't valid amplitude calibration values in use.? Run "CAL FREQ & AMPTD", then store.
Was your supercap defective that you replaced it?? Did you backup your correction constants first?
You probably lost your stored (and valid) amplitude calibration values when you replaced the battery and supercap, which is why it won't store just the frequency values.
-mark
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Re: HP 8648C keyboard mostly dead
Hi Kirb,
I own an HP 8648B but I don't currently have access to it, since I'm not in the lab over the weekend.
I could imagine that the attenuator stepping doesn't take place, unless the RF output is enabled, so that could explain the lack of clunking, since you can't enable the RF output.
If that is so, it could just be keyboard a problem:
The keyboard employs a selectively silverpaint-covered foil, which suffers from multiple keypressing and corrosion / air pollution, leading to interruptions.
Notwithstanding the fact that usually quite a lot of places are affected, these are really easy to repair by applying some (very little) conductive (silver containing) paint to bridge the gaps in the traces.
If this is what happened with your instrument, you'll probably see that in some areas, operating the silicone rubber keypad has caused prolonged rubbing over the conductive traces connecting the keypads (interleaved combs), even though a plastic layer should prevent that from happening.
Easy to find out (after some disassembly), easy to repair. Be careful with the conductive paint, since even an almost invisible smudge causes enough conduction to confuse the keyboard circuits.
Good luck!
Raymond
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You refer to a book but no link? or how to read it alternatively it could be uploaded as a PDF to the file section on this site ??An alternatively solution to display a diode detector on an analogue display could be HP 7563A Log Voltmeter / Amplifier, as we use one in an education lab?The 415 SWR meter dues take an EXTAL input but requires a modulated RF input ?But I think trying to use a 432 for an EXTAL input is a case of using the wrong instrument for the job ? ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Radu Bogdan Dicher
Sent: 04 February 2022 23:20
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP detector ? Jeff, "The guy" is asking whether you'd be willing to share directions for building a suitable detector for my initial request? :) In my book, DIY is the way, if possible. Thank you much in?advance.? ? No can do: apples vs oranges 432 uses RF thermistors, not set up for diodes.
In a message dated 2/4/2022 5:38:23 PM Eastern Standard Time, joeprice@... writes:
Hi Jeff,?
How about posting in files or here on how to build your own HF detector for HP432.?
Tnx? ? Joe? ?wa9cgz
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Re: HP 11664A Detector - DIY equivalent?
Those pics are from me.
As a detector I used Pasternack pe8000-50.
Zero Bias Detector, BNC, Positive Video Out, 0.1 MHz to 1 GHz
No longer supported.
Jos PA0AMX
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am trying to repair my 8596E, new battery and supercap, it does autocalibrate in frequency but does not do data stored (cal: data not stored), I ask if the stored should do it regardless of having autocaled in amplitude . Day and time works regularly.
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Re: HP 11664A Detector - DIY equivalent?
OK Paul- all sorted! Thanks DaveB, NZ ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Paul Bicknell
Sent: Saturday, February 05, 2022 11:52
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 11664A Detector - DIY equivalent?? Hi? ok? I made a mistake as quoted? the D when I should have quoted C ? The 11664A is up to 18 Ghz? the? 11664C is the detector adapter this allows you to use any diode detector with the scaler analyser and I have personally used this up to 75 ghz The 11664D is 26 to 40 Ghz? with? wave guide input? and I do not have any documentation on this part ? So basically we now have ( as I have just uploaded them? ) the operator and service manuals including? the CCT for the 11664 A and the C? on this site and that is all that is available at this time ? Regards Paul ? ? ? But that¡¯s info re the home built C version, NOT the D.? Where is the data/cctry for the D version? ?I¡¯d like to see the HP original schematic for the D version as well as? any available data re a home built version of it. DaveB, NZ ? ? ? /g/HP-Agilent-Keysight-equipment/photo/68507/806445?p=Created%2C%2C%2C20%2C2%2C0%2C0 ? hi it is in their? picture 6 number 11664 ? ? Can only see info re home built 11664C in photos section- perhaps I¡¯m blind¡.? DaveB, NZ ? ? Hi look in the ?photos on this site and you will have the 11664D admittedly not that good but also a new design based on modern components Paul B ? ? 11664D schematic somewhere? The manual in? files section of grps io is ops only, no ccts. DaveB, NZ ? ? I have done as Jeff described a number of times to get someone a working scaler analyser I use the 11664 C detector adapter for frequencies above 18 Ghz? so if you are making an adapter without using an old 11664 then the circuit used in the D version is actually better and easier to configure to different detectors ? Also I have seen possibly on this site a modern board lay out using modern components Paul B ? From: [email protected] [mailto:[email protected]] On Behalf Of Jeff Kruth via groups.io
Sent: 04 February 2022 09:15
To: tonycox01@...; [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 11664A Detector - DIY equivalent? ? Yes, I have. Polarity of detector doesnt matter, as the signal is chopped at 27.8 KHz. Best bet is get a blown detector then remove the detector bulkhead and fashion a small aluminum sheet metal plate to hold a BNC, replacing the bulkhead with this. It is the same as an HP11664C detector adapter. Easy-peasy. Works great.
In a message dated 2/4/2022 3:52:30 AM Eastern Standard Time, tonycox01@... writes:
Hi,
I've been looking for a couple of HP 11664 detectors for a network analyser but was put off by the sky high price - even for second hand items of dubious condition.
I've seen a web page showing a DIY equivalent using a?33330B?(positive)?detector and an amplifier replicated from the HP service manual.I was wondering if this is a sensible/realistic thing to attempt? Has anybody ever tried this?
thanks
Tony
|
Jeff, "The guy" is asking whether you'd be willing to share directions for building a suitable detector for my initial request? :) In my book, DIY is the way, if possible. Thank you much in?advance.? Radu, aka "the guy."?
Hi Joe!
No can do: apples vs oranges 432 uses RF thermistors, not set up for diodes.
73
Jeff
In a message dated 2/4/2022 5:38:23 PM Eastern Standard Time, joeprice@... writes:
?
Hi Jeff,?
How about posting in files or here on how to build your own HF detector for HP432.?
Tnx? ? Joe? ?wa9cgz
|
Re: HP 11664A Detector - DIY equivalent?
Hi? ok? I made a mistake as quoted? the D when I should have quoted C ? The 11664A is up to 18 Ghz? the? 11664C is the detector adapter this allows you to use any diode detector with the scaler analyser and I have personally used this up to 75 ghz The 11664D is 26 to 40 Ghz? with? wave guide input? and I do not have any documentation on this part ? So basically we now have ( as I have just uploaded them? ) the operator and service manuals including? the CCT for the 11664 A and the C? on this site and that is all that is available at this time ? Regards Paul ? ?
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Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of Dave Brown
Sent: 04 February 2022 22:03
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 11664A Detector - DIY equivalent?? But that¡¯s info re the home built C version, NOT the D.? Where is the data/cctry for the D version? ?I¡¯d like to see the HP original schematic for the D version as well as? any available data re a home built version of it. DaveB, NZ ? ? ? /g/HP-Agilent-Keysight-equipment/photo/68507/806445?p=Created%2C%2C%2C20%2C2%2C0%2C0 ? hi it is in their? picture 6 number 11664 ? ? Can only see info re home built 11664C in photos section- perhaps I¡¯m blind¡.? DaveB, NZ ? ? Hi look in the ?photos on this site and you will have the 11664D admittedly not that good but also a new design based on modern components Paul B ? ? 11664D schematic somewhere? The manual in? files section of grps io is ops only, no ccts. DaveB, NZ ? ? I have done as Jeff described a number of times to get someone a working scaler analyser I use the 11664 C detector adapter for frequencies above 18 Ghz? so if you are making an adapter without using an old 11664 then the circuit used in the D version is actually better and easier to configure to different detectors ? Also I have seen possibly on this site a modern board lay out using modern components Paul B ? From: [email protected] [mailto:[email protected]] On Behalf Of Jeff Kruth via groups.io
Sent: 04 February 2022 09:15
To: tonycox01@...; [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 11664A Detector - DIY equivalent? ? Yes, I have. Polarity of detector doesnt matter, as the signal is chopped at 27.8 KHz. Best bet is get a blown detector then remove the detector bulkhead and fashion a small aluminum sheet metal plate to hold a BNC, replacing the bulkhead with this. It is the same as an HP11664C detector adapter. Easy-peasy. Works great.
In a message dated 2/4/2022 3:52:30 AM Eastern Standard Time, tonycox01@... writes:
Hi,
I've been looking for a couple of HP 11664 detectors for a network analyser but was put off by the sky high price - even for second hand items of dubious condition.
I've seen a web page showing a DIY equivalent using a?33330B?(positive)?detector and an amplifier replicated from the HP service manual.I was wondering if this is a sensible/realistic thing to attempt? Has anybody ever tried this?
thanks
Tony
|
Hi Joe!
No can do: apples vs oranges 432 uses RF thermistors, not set up for diodes.
73
Jeff
In a message dated 2/4/2022 5:38:23 PM Eastern Standard Time, joeprice@... writes:
?
Hi Jeff,?
How about posting in files or here on how to build your own HF detector for HP432.?
Tnx? ? Joe? ?wa9cgz
|
ESG-DP E4437B Signal Generation Issue
Hi all,
?
I have a problem with my E4437B that started gradually as jitter, but now just outputs white noise.? I used to repair ESG RF boards, and know the generators relatively well, but haven't seen this issue before.
I had been measuring internal stability by using my 53132A?(500KHz for best ?Hz resolution), set with an offset, and recording the resulting offset, recording a range of 1 - 15 ?Hz. Just recently, it started getting worse, and worse, and at times jumping to outrageous frequency errors.? ?However, there were no indicated errors until today.
?
?
The bandpass filters are switching properly, but show white noise covering the entire bandwidth of the filters, and the white noise levels change drastically with frequency, and am now seeing an "UNLEVEL" indication, which is likely due to to the signal generation failure.? One note, when I select 400MHz, I get a secondary output at 800MHz (-55dBm with output set at 0dBm), which attenuates severely with only a few hundred KHz change.? The high level of the 800MHz is likely due to the output board trying to ink out as much level as possible, but is not able to.
?
My first dread was that it might be the YIG, as they are such a pain, and very expensive (I don't have any experience with them, just the RF boards in the cage).? I have also been considering the U313 (1GC1-4210) Frac-N divider on the E4423-60019 SYNTH BD, which I know is a weak spot.? I haven't opened it up yet, but plan to in the next few days.? Since the YIG drives the FRAC-N board directly, I will check for a clean signal there, then at the output of the FRAC-N divider.? Fortunately, I have an E4404B spectrum analyzer, so I can look directly at the YIG output.
Fortunately, I have a couple new, but slightly damaged (scratched on top of the chip, which obliterated the part number) 1GC1-4210 replacements, as I used to repair these boards, and the regular rework person messed up a few chips with tweezers.
Thanks in advance for the help.
Tom -- KJ6SVS --
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Hi Jeff,?
How about posting in files or here on how to build your own HF detector for HP432.?
Tnx? ? Joe? ?wa9cgz
|
Re: HP 11664A Detector - DIY equivalent?
But that¡¯s info re the home built C version, NOT the D.? Where is the data/cctry for the D version? ?I¡¯d like to see the HP original schematic for the D version as well as? any available data re a home built version of it. DaveB, NZ ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of Paul Bicknell
Sent: Saturday, February 05, 2022 10:08
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 11664A Detector - DIY equivalent?? /g/HP-Agilent-Keysight-equipment/photo/68507/806445?p=Created%2C%2C%2C20%2C2%2C0%2C0 ? hi it is in their? picture 6 number 11664 ? ? Can only see info re home built 11664C in photos section- perhaps I¡¯m blind¡.? DaveB, NZ ? ? Hi look in the ?photos on this site and you will have the 11664D admittedly not that good but also a new design based on modern components Paul B ? ? 11664D schematic somewhere? The manual in? files section of grps io is ops only, no ccts. DaveB, NZ ? ? I have done as Jeff described a number of times to get someone a working scaler analyser I use the 11664 C detector adapter for frequencies above 18 Ghz? so if you are making an adapter without using an old 11664 then the circuit used in the D version is actually better and easier to configure to different detectors ? Also I have seen possibly on this site a modern board lay out using modern components Paul B ? From: [email protected] [mailto:[email protected]] On Behalf Of Jeff Kruth via groups.io
Sent: 04 February 2022 09:15
To: tonycox01@...; [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 11664A Detector - DIY equivalent? ? Yes, I have. Polarity of detector doesnt matter, as the signal is chopped at 27.8 KHz. Best bet is get a blown detector then remove the detector bulkhead and fashion a small aluminum sheet metal plate to hold a BNC, replacing the bulkhead with this. It is the same as an HP11664C detector adapter. Easy-peasy. Works great.
In a message dated 2/4/2022 3:52:30 AM Eastern Standard Time, tonycox01@... writes:
Hi,
I've been looking for a couple of HP 11664 detectors for a network analyser but was put off by the sky high price - even for second hand items of dubious condition.
I've seen a web page showing a DIY equivalent using a?33330B?(positive)?detector and an amplifier replicated from the HP service manual.I was wondering if this is a sensible/realistic thing to attempt? Has anybody ever tried this?
thanks
Tony
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Froggie the Gremlin
Michael A. Terrell
Jared Cabot
Paul Bicknell
Jos Raven PA0AMX