Re: HP 3325A amplitude problem
Thank you for the input. I'll try cleaning as suggested , the service manual describes the details about the relays, so I'll keep you posted.
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Goran
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Seeking manual for HP 651B test oscillator
Would anyone have a HP 651B test oscillator OP/SVC manual covering serials around 1200A and later (1980’s manufacture)? All of the ones I can find are referring to serials in the very early range of 6xx (1960’s manufacture).
Also, even if you don’t have a spare some information on a manual part number that would be covering that range would be helpful.
Thanks,
Greg
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Re: HP 8566B issue above 18.5GHz ?
Wojciech,
?
Since the 8566B switches between band 3 to band 4 in the upper band at 18.5 GHz and the 8341B/8340B switches at 20.0 GHz, I would say it is pretty conclusive it is the 8566B that needs adjustments in this case.
?
Regards
Saevar
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Re: HP8753E, 8753D, 8753ES 3.5" disk drive replacement reference information
Glad I am not the only
one with similar issue....LOL
搁别苍é别
On 12/10/24 7:23 AM, Renaud F5ZR via
groups.io wrote:
toggle quoted message
Show quoted text
On Tue, Dec 10, 2024 at 03:48 PM, Scott Vance wrote:
Yes, my spelling sucks, that's on me.? As a bonus, I
can misspell things in at least 3 languages.
Excellent! Better than not mispelling in only one!
Renaud
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Re: HP8753E, 8753D, 8753ES 3.5" disk drive replacement reference information
On Tue, Dec 10, 2024 at 03:48 PM, Scott Vance wrote:
Yes, my spelling sucks, that's on me.? As a bonus, I can misspell things in at least 3 languages.
Excellent! Better than not mispelling in only one!
Renaud
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Re: HP8753E, 8753D, 8753ES 3.5" disk drive replacement reference information
Yes, my spelling sucks, that's on me.? As a bonus, I can misspell things in at least 3 languages.
?
Rich - I am a little confused regarding the GoTek options.? I am seeing lots of these drives on epay, but all of the ones I am seeing have a different interface at the back of the unit (i.e. not plug and play) and in general are a larger drive size (i.e. won't fit in the slot which is 12.5 x 101.5 x 130 mm).? What am I missing?? Is there a commercial GoTek option which can be easily adapted to these machines or is modification required?
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Re: 5350/51/52 Sampler Replacement?
Thank you for your reply. I just went and made some quick measurements. J2 (LO out) is at +13.78dBm on my power meter, and the sweep from 292-355 MHz looks good on my spectrum analyzer.?
?
With a 2GHz input, I can get a phase lock and accurate reading down to -22dBm. At 4GHz, I cannot get an accurate reading at all, even though the LED's are lit for phase lock. It's reading about 700 MHz low (3.313 GHz), even at +7 dBm from my signal generator.?
?
If you look at the noise profile from the input port of my 5350B, it makes sense. The noise peaks around 4 GHz, and is about 20 dBm lower at 2 GHz. So with high enough input levels it is possible to overcome the noise. I would expect it to be the same at higher frequencies as the noise floor drops off again by 10 or so GHz, but the signal generator I was using only went to 4 gig so I didn't test that.?
?
I had posted about this a few months back on the EEV Blog and it was suggested a diode in the U1 had likely shorted. This seems to make sense, given the amount of power present on the input connector. For reference, I also have a 5347A counter/power meter that uses the same sampler module, and when connected to the spectrum analyzer, the amount of "leakage" from the 50 ohm input is just over the noise floor, or about -50 dBm. I can get good sensitivity on that counter down to -40 dBm at all frequencies.?
?
?
?
On Mon, Dec 9, 2024 at 03:58 PM, Yves Tardif wrote:
I made others measurements on my 8350B:
?
The signal output to the sampler, that is J2, and the signal has a variable frequency of 292-355MHz approximately (in theory: 295-350MHz), with a level of +14dBm.
No signal connected to input1.
To measure the LO output +14dBm at J2, I removed the loop from the module, and with a SMB to BNC adapter, I connected to my Spectrum.
?
I now put a signal at 1GHz, but at -40dBm, so that the meter does not synchronize.
So, you see the frequency values ??that the IF output of the sampler can take (theory: 500kHz-175MHz).
After this test, I put the 1GHz signal at 0 dBm, the meter synchronizes (phase-locked) and we can see one of the values ??that the IF output can take.
The meter is continuously measuring, so we can see the frequency excursion.
To do the closed loop measurement, I used a SMB test of my design, and the tap was -19dB, the insertion loss on the main line was -1.1dB.
By making several attempts, the IF outputs could be at another frequency, but the result displayed remains the same after processing.
?
In summary:
The LO measurement is +14dBm at J2 towards the sampler.
For a 1GHz -40dBm input, I get -37.45dBm at the IF output (not locked)
For a 1GHz 0dBm input, I get -1.14dBm at the IF output (locked).
?
If you have the correct RF levels input-output to the sampler and the frequency range is similar, if the meter is not phase locked, then the problem is probably not in the sampler, but rather elsewhere like in the A5/A6 section for example.
?
Hope this information helps you.
?
Yves
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Re: HP 3325A amplitude problem
On Tue, Dec 10, 2024 at 12:55 AM, Raymond Domp Frank wrote:
The 3325A uses latching relays in its attenuator. These are mounted on the PCB and held with springs. The contacts between relays and PCB are prone to becoming dirty after many years. Remove the relay and clean the PCB and relay contacts with IPA. Do *not* use anything abrasive and be careful not to bend or even break a contact.
?
?
I guess I should clarify: The relays are an open construction: Their switching contacts employ the gold-plated PCB pads.
Once you see it, it'll become clear.
?
Raymond
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Re: 5350/51/52 Sampler Replacement?
Hi, ? First, I did the spurious comparison by measuring directly at input 1 of the 5350B, but I don't have an external 10dB attenuator. It's clear that you have much more spurious than my 8350B. ? 
? I made others measurements on my 8350B: ? The signal output to the sampler, that is J2, and the signal has a variable frequency of 292-355MHz approximately (in theory: 295-350MHz), with a level of +14dBm. No signal connected to input1. To measure the LO output +14dBm at J2, I removed the loop from the module, and with a SMB to BNC adapter, I connected to my Spectrum. ? I now put a signal at 1GHz, but at -40dBm, so that the meter does not synchronize. So, you see the frequency values ??that the IF output of the sampler can take (theory: 500kHz-175MHz). After this test, I put the 1GHz signal at 0 dBm, the meter synchronizes (phase-locked) and we can see one of the values ??that the IF output can take. The meter is continuously measuring, so we can see the frequency excursion. To do the closed loop measurement, I used a SMB test of my design, and the tap was -19dB, the insertion loss on the main line was -1.1dB. By making several attempts, the IF outputs could be at another frequency, but the result displayed remains the same after processing. ? In summary: The LO measurement is +14dBm at J2 towards the sampler. For a 1GHz -40dBm input, I get -37.45dBm at the IF output (not locked) For a 1GHz 0dBm input, I get -1.14dBm at the IF output (locked). ? If you have the correct RF levels input-output to the sampler and the frequency range is similar, if the meter is not phase locked, then the problem is probably not in the sampler, but rather elsewhere like in the A5/A6 section for example. ? Hope this information helps you. ? Yves
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Re: HP 3325A amplitude problem
The 3325A uses latching relays in its attenuator. These are mounted on the PCB and held with springs. The contacts between relays and PCB are prone to becoming dirty after many years. Remove the relay and clean the PCB and relay contacts with IPA. Do *not* use anything abrasive and be careful not to bend or even break a contact.
Let us know the result!
?
Raymond?
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HP 3325A amplitude problem
Just noticed that some of the amplitude levels are not correct on my HP 3325A that worked without problems for a long time. So before starting anything I wonder if anyone has experienced something similar: I setup sine signal in the 1 mV increments and from 1 mV rms to 10 mV rms levels are correct. Between 11 mV and 36 mV rms the levels can be few mV below or completely absent, haven't tested yet the other ranges. I'm doing measurements at 1kHz. Haven't tried other frequencies yet.
Some other observations - there is DC component present at the higher levels which I noticed earlier, ( at one occasion I setup sine signal at 2 V rms and I had 140 mV DC present while DC offset was set to zero)and DC offset is out of tolerance ( and we are talking about significantly out ( if I remember correctly manual allows 0.4 % of the set value for error of DC offset and I was getting error in the range of 4 % to 5 %.
Any input is appreciated.
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Thank you
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Re: HP 54720A comes on briefly then shuts off
Yes, it is the same supply!
toggle quoted message
Show quoted text
On Dec 9, 2024, at 15:51, Tim Tuck <timt@...> wrote:
?
Hi Yves,
Yes, my PSU is a 0950-2211
and I'd be interested in your experiments.
It'd be nice if we could come up with some
methodology to verify these things.
regards
Tim
On 9/12/24 15:47, Yves Tardif via
groups.io wrote:
Hi,
?
I don't have a
54720A, but an 83480A, similar to the 54750A. After checking
the 54720A service manual, it seems that the power supply is
the same.
My question is: is
the power supply of the 54720A really a Yokagawa PS495-0101,
the HP number is 0950-2211 for my 83480A.
?
If the number is the
same, I could try to run it outside (I have a spare power
supply to experiment).
But I know that if
there is no fan, or if it does not turn or stops turning,
then the power supply will go into shutdown mode...or
simply, will not turn on.
So, I have to find a
way to simulate the signal or connect a fan to it.
?
Without an electrical
diagram, it is quite difficult to repair this power supply,
but I succeeded three times on this model...and it was
painful...but feasible and inexpensive.
?
Yves
|
Re: HP 54720A comes on briefly then shuts off
Hi Yves,
Yes, my PSU is a 0950-2211
and I'd be interested in your experiments.
It'd be nice if we could come up with some
methodology to verify these things.
regards
Tim
On 9/12/24 15:47, Yves Tardif via
groups.io wrote:
toggle quoted message
Show quoted text
Hi,
?
I don't have a
54720A, but an 83480A, similar to the 54750A. After checking
the 54720A service manual, it seems that the power supply is
the same.
My question is: is
the power supply of the 54720A really a Yokagawa PS495-0101,
the HP number is 0950-2211 for my 83480A.
?
If the number is the
same, I could try to run it outside (I have a spare power
supply to experiment).
But I know that if
there is no fan, or if it does not turn or stops turning,
then the power supply will go into shutdown mode...or
simply, will not turn on.
So, I have to find a
way to simulate the signal or connect a fan to it.
?
Without an electrical
diagram, it is quite difficult to repair this power supply,
but I succeeded three times on this model...and it was
painful...but feasible and inexpensive.
?
Yves
|
Re: Shielded probe cables?
OK. Not a fan of fine pitch :) But I will try to use the pods from my Agilent 54622D with the 32-ch analyser and see if it works. They have a straight 2,54mm pitch IDC connector.
|
Re: HP 54720A comes on briefly then shuts off
Hi, ? I don't have a 54720A, but an 83480A, similar to the 54750A. After checking the 54720A service manual, it seems that the power supply is the same. My question is: is the power supply of the 54720A really a Yokagawa PS495-0101, the HP number is 0950-2211 for my 83480A. ? If the number is the same, I could try to run it outside (I have a spare power supply to experiment). But I know that if there is no fan, or if it does not turn or stops turning, then the power supply will go into shutdown mode...or simply, will not turn on. So, I have to find a way to simulate the signal or connect a fan to it. ? Without an electrical diagram, it is quite difficult to repair this power supply, but I succeeded three times on this model...and it was painful...but feasible and inexpensive. ? Yves ? 
? ?
toggle quoted message
Show quoted text
-----Message d'origine-----
De?: [email protected] <[email protected]> De la part de Tim Tuck
Envoyé?: 8 décembre 2024 18:22
??: [email protected]
Objet?: [HP-Agilent-Keysight-equipment] HP 54720A comes on briefly then shuts off ? Hi all, ? My 54720A comes on briefly before switching itself off. ? No modules in frame. ? Been through section 5-12 of the service guide and I have all rail LEDs green and then LED1 on and LED2 off. ? Its not hot since its been off for a long time so I thought about the overload protection and did the resistance tests in fig 5-7 and all rails test as per instruction. ? Doing the instructions for the 5.1v and 120v rails pass as well. ? Before I proceed further with pulling cards, I thought I'd ask if there was a common fault or two I could go check for 1st. ? I'd also like to know if anyone has managed to power up the PSU outside the chassis for testing and what was the connectivity required to do that. ? If I can power up the PSU outside the frame I an eliminate that as a cause. ? thanks ? Tim ? ? ? ? ? ? ?
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Hi, Greg,
?
I'm Andrea, IW2FDH, from Italy,
?
Could you please post the? schematic of the HP 8980a/8981a power supply ?? Even without the removable vertical control board
?
thanks in advance
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Re: HP 54720A comes on briefly then shuts off
I have worked on many 54720, and the power supply is always the culprit of most issues. I was never able to find the schematic of that power supply!
toggle quoted message
Show quoted text
On Dec 8, 2024, at 17:22, Tim Tuck <timt@...> wrote:
?Hi all,
My 54720A comes on briefly before switching itself off.
No modules in frame.
Been through section 5-12 of the service guide and I have all rail LEDs green and then LED1 on and LED2 off.
Its not hot since its been off for a long time so I thought about the overload protection and did the resistance tests in fig 5-7 and all rails test as per instruction.
Doing the instructions for the 5.1v and 120v rails pass as well.
Before I proceed further with pulling cards, I thought I'd ask if there was a common fault or two I could go check for 1st.
I'd also like to know if anyone has managed to power up the PSU outside the chassis for testing and what was the connectivity required to do that.
If I can power up the PSU outside the frame I an eliminate that as a cause.
thanks
Tim
|
HP 54720A comes on briefly then shuts off
Hi all,
My 54720A comes on briefly before switching itself off.
No modules in frame.
Been through section 5-12 of the service guide and I have all rail LEDs green and then LED1 on and LED2 off.
Its not hot since its been off for a long time so I thought about the overload protection and did the resistance tests in fig 5-7 and all rails test as per instruction.
Doing the instructions for the 5.1v and 120v rails pass as well.
Before I proceed further with pulling cards, I thought I'd ask if there was a common fault or two I could go check for 1st.
I'd also like to know if anyone has managed to power up the PSU outside the chassis for testing and what was the connectivity required to do that.
If I can power up the PSU outside the frame I an eliminate that as a cause.
thanks
Tim
|
Re: 5350/51/52 Sampler Replacement?
Looks like plenty of strobe. Can you put a CW say a few GHz 0 dBm in the input, and tap into the IF signal from the IF amp output to show on the SA? If it's zero or very low compared to spec, then try to look at it near the input to the IF amp.
?
Ed
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Re: 5350/51/52 Sampler Replacement?
Hi Ed, thank you for your reply.?
?
Regarding how I concluded the U1 was bad,? strong signals are making it through, as seen on my 8566B (pic below). This was with attenuation at -10dB and a 10dB pad in-line. SA was connected directly to the input on the 5350B. I have no idea on the history of this unit, or how that may have happened, as I received it this way.?
?
I'm sure there are a lot of these floating around in the world and was hoping someone had cobbled together an acceptable replacement for the 5088-7071 from modern components. 20 GHz components are certainly more available now than they were 40 years ago!?
?
?
?
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Anders