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Re: HP 8660B/86602B developed output stability problem, getting-started suggestion(s) request

 

Set the frequency to 0.0 MHz.? ? Does the RF level meter in the RF section go to zero??
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The phase lock loop that most often needed adjustment is the 350 to 450 MHz loop (in the swing-out assy on top).? Check its output with the small spectrum analyzer or a counter.? ? This loop goes moves in 10 MHz steps.? I probably adjusted these a few hundred times as the VCO would drift out of capture range.? ?Every time an 8660 would come in for anything I'd check its adjustments.? ?
The other smaller step-size loops were more stable or at least less problematic.? ?They also had pre-tuning to push the VCO closer to nominal range.? ??
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Definitely check the power supplies first if you have not already (use a scope to check for ripple).?
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If you had an 86601A RF section, 350-450 loop is still required as you might already know.? ? ?
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If this was still the mid to late 90's I'd be of much better help.? ? I was the last tech in the HP repair center in New Jersey to work on these old sig gens before all the HP service centers were consolidated to CA.??
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Re: HP 8660B/86602B developed output stability problem, getting-started suggestion(s) request

 

First experiment - swapped 11661B module with a supposedly-OK "just in case" spare I had picked up a long time ago (with understanding that the 11661B manual has an adjustment procedure to use when module swap/move occurs, which I didn't perform).

The output problem remains (fluctuating around 100-200 kHz below the set frequency), so taking this as a clue that the 11661B is not necessarily the problem, and starting into the fault finding tree in the 8660B manual.
Re: Thoughts on Hakko FR301

 

I have a job that requires removing a 56 pin PCB connector from an HP 6 (or so) layer motherboard.
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I'm considering the Hakkp FR301 desoldering tool - if anyone has experience using this tool for a similar job, I'd like to hear about it.? In particular is it capable of supplying adequate heat for a job like this.
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If you have experience, please speak up!
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Cheers!
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Bruce
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Re: Accurately measuring 1000pF and 100pF capacitors, to calibrate 4276A?

 

Well, I just picked up an Arco SS-32 Precision Standard Capacitor Set for the equivalent of about $75 all up, so that's a start. It has some missing values and a number of doubled up values too (maybe it is a set built up from values laying around rather than a 'complete set'), but the price was good anyway. Once I get it in my hands, I can see how each standard is constructed, and once I get my gear calibrated, I can complete the set with my own DIY capacitors.
It seems to have become the Electrocube ss-32 at some point, so at least parts are still available... Stated at 0.1 - 0.5%, so sort-of getting close to what I need, closer than I was yesterday anyway...
https://www.electrocube.com/pages/ds-pfc-precision-film-capacitors-and-standards-data-sheets
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My set doesn't have a 1000pF cap, but it does have a 100pF cap, so I'm now halfway there sort of, just need to get these caps all measured and such.
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@Richard Parrish, where abouts are you located?
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Thanks all for the info so far! Greatly appreciated. :)
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Jared
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Re: 8753C VNA option upgrade

 

Hi Caesar,
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I hope you're well. Yes, now I remember that did come from you. Thank you so much for the service you provide, you're a credit to the community!
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J.
Re: HP Agilent 8753ES VNA repair [Help]

 

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Hi,

?

To make a first comparison, here is the output of my 8753ES at 1GHz, CW mode, 0dBm output, Trigger HOLD, measured on a Spectrum.

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If you have a similar image, the PLL A11 would be correct.

You do not have an UNLOCK message, this means that you have enough signal to maintain synchronization.

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If the signal going to the sampler R was attenuated, the average during an S11 measurement would give an average signal offset from the reference (when nothing is connected to port #1).

But looking at your image, test S11, nothing connected to port #1, apart from the noise everything seems correct.

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Do a test from 30kHz to 250kHz, the A11 module is bypassed, if the problem persists, A11 is not the cause.

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Either the problem comes from A7, or it is further away like on the IF DIGITAL.

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Make measurements on the samplers separately, MEAS A, B and R. Do you have the noise problem on all samplers.

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I will wait for your answer, and I will be able to make comparative measurements on my VNA 8753ES.

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Yves

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Re: E5052A Power On Test (3.3V Bus Supply)

 

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Sounds about right. ?60 kHz is right in the range of a switching regulator of that era.

I didn’t find a signal source analyzer around the particular lab I frequent, but I’d be very surprised if there weren’t one somewhere in this building. ?Literally tons of vintage test equipment lying around here, much of it from the old Hughes Aircraft days. ?Glad you at least figured out where the spur was coming from.

Jim


On Feb 24, 2025, at 12:53?PM, jmr via groups.io <jmrhzu@...> wrote:

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Turning the backlight off makes the spurious term go away when probing :)
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There is a soft menu button that turns off the backlight and pressing this makes the spurious vanish on the probe (that feeds to another spectrum analyser).
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Also if I do a screen grab via Excel and GPIB (with the backlight ON) the 60kHz spurious is present on the spectrum from the baseband input. But if I grab the screen with the backlight off the baseband spectrum is clean on the grabbed screen image in Excel. A huge improvement.
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I guess I can live with this when grabbing screen plots as (hopefully) I can add the 'backlight off' command to the excel routine.
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So screen grabs will look much better. I'll have a look for the backlight command in the programming guide...
HP Agilent 8753ES VNA repair [Help]

 

Hi everyone,
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I am looking for some help on the repair of my 8753 VNA.?

I took some time trying to find the problem it myself with the service manual without success.?

The unit was working great and failed during my last filter mesurement. The signal is now noisy on port 1 and 2 (in S11,S22 ans S21), even if I do a new calibration.?
I have no error on power on. Have you ever entered this type of failure ?

I was first thinking of an ESD failure but it do not seems to be the case.?
The two input couplers mesure OK. I have 16 dB of coupling loss on port 1 and port 2. Visual inspection do not show any damage on the RF patch.?
The solid state switch also seems to be OK. I have 2 dB of loss between the input and the two output of the SP2T.?

In span zero mode I mesure a RF signal at the right frequency in the 1 MHz- 6 GHz band. Output power is also OK. The stepped attenuator seems to be Ok, signal source is there.?

The only problem I can see here is when I look at the RF out signal on a spectrum analyser, the RF signal do not seems to be locked. ?
When I reduce the SPAN on the VNA, I can see a lot of spike on the response.?
From what I understand, I now need to check the ?A7 Pulse generator diode stage and the A11 Phase lock board. The red LED on the A11 board is blinking but do not stay ON.
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Could you help me from this point on this repair ? Thank you ??
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S11 signal, port 1 open SPAN 6 GHz:
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S11 signal, port 1 50 Ohms load, ?SPAN 6 GHz:
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S11 signal OPEN SPAN 1 MHz
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S11 Signal SPAN 6GHz with 50 ohms load


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Re: Accurately measuring 1000pF and 100pF capacitors, to calibrate 4276A?

 

Both your 4276a and 4263b can measure ESR. So you may take the Henry Parsons Hall way, which he did at general radio with the digibridges:
First he calibrates the measurement-frequency deviation.
Secound he uses calibrated resistors and no capacitors for calibration.
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For your case: Check the oscillator frequency for drift.
Then take your calibration resistors and measure them with your 34461a. Now measure and tweak your 100pF and 1000pF calibation capacitors until your calibrations resistors measure the same values on the 4276a as on the 34461a.
Build from relative new (post year 2000) high voltage foil or Y2 capacitors - they have very low D, but D is never nagative.
Check with your 4263b and DER-EE 5000 - both with short and open calibration.
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By the way: my 4274a/4275a did not drift out of spec in the mid ranges, for me f > 1 MHz ranges are hard to check . Maybe the 4276a behaves the same, if you didn't tweek it. My 4263b drifted less then 1%, but more then the 4274a, if i remember correct. But all are not in the class of the genrad 1689 which has the most simple design and calibration procedure and like the 4274a no special parts.
(the 4274a/4275a are a repair nightmare compared to the digibridges, but have the better user interface).
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Re: E5052A Power On Test (3.3V Bus Supply)

 

Turning the backlight off makes the spurious term go away when probing :)
?
There is a soft menu button that turns off the backlight and pressing this makes the spurious vanish on the probe (that feeds to another spectrum analyser).
?
Also if I do a screen grab via Excel and GPIB (with the backlight ON) the 60kHz spurious is present on the spectrum from the baseband input. But if I grab the screen with the backlight off the baseband spectrum is clean on the grabbed screen image in Excel. A huge improvement.
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I guess I can live with this when grabbing screen plots as (hopefully) I can add the 'backlight off' command to the excel routine.
?
So screen grabs will look much better. I'll have a look for the backlight command in the programming guide...
Re: E5052A Power On Test (3.3V Bus Supply)

 

Hi Jim, thanks.
I've just spent some time fishing around the outside of the chassis with a loop probe and the 60 kHz spurious is from the front of the instrument around the display. It isn't a single tone, it is spread over many kHz on the high side of 60 kHz and looks to be caused by digital traffic. It might be the display causing it. It seems to be at 59 kHz and it may be backlight related but it looks like it has some digital traffic on it.?
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Probing around the screen area of an E5071B VNA (I think this has the same touch screen display) shows exactly the same waveform so it is definitely screen related in some way. I'm not sure how this is getting into the baseband path but because it is also there on the main phase noise display I think it is getting in at the ADC/DSP module, possibly via a power supply rail. Hopefully a tired decoupling cap is the cause.
Re: E5052A Power On Test (3.3V Bus Supply)

 

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Hi, Jeremy. ?Let me take a look around the labs here at Raytheon. ?Might be an E5052A or two that I could fire up. ?Give me a couple hours.

Jim Ford?
Laguna Hills, California, USA


On Feb 24, 2025, at 10:17?AM, jmr via groups.io <jmrhzu@...> wrote:

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I wonder if anyone here has experience or access to an Agilent E5052A signal source analyser? Mine is about 20 years old and is recently showing signs of unreliability.
The main symptom is an occasional power on self test fail and it then reports issues with a 3V3 power supply voltage on the A3 DSP/ADC board where it reads low at typically 2.96V. I think a pass requires >2.96V but this may be firmware dependent. My E5052A is running the latest firmware V2.51.

I think this 3V3 supply is common across the backplane but it gets reported as an A3 test in the service menu. The 5V PSU rail also reads low at between 4.7 and 4.8V but this is still a pass (shows true for the test result)
Also, for several years now it has shown a stubborn internal spurious at 60 kHz at a very low level. This very slightly spoils any phase noise measurements even though it shows up at about -140dBc then the trace is in phase noise mode in dBc/Hz. I'm not sure what causes this internal 60 kHz term, it may be from a PSU or the display or a divided clock. It may be that the 60kHz spurious term is a feature of this analyser as it is present on all my plots dating back over 13 years. It's not caused by anything nearby to the instrument as it does it regardless of position or proximity to other equipment. Plus the other E5052A I've used in the past (in a different location) is exactly the same.

The 60kHz spurious is also present when I swap across to the baseband input even with a very clean LF signal fed to the 0-40 MHz baseband input. So this spurious must be getting in at the ADC if it affects the baseband input as well.
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I've seen similar on another E5052A that also shows a lowish 3V3 voltage (but it never shows a power on test failure) and it also has the permanent 60 kHz spurious on all phase noise tests on the main RF input.
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The service menu password is only three characters long and is 'kid'
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If anyone has access to a healthy E5052A could they enter the service menu and do a manual Power On Test (POT) in the service menus? Then report the 5V and 3.3V results for the A3 module
Mine shows anything from 2.91V to 3.05V and I think the pass/fail threshold for the POT is somewhere around 2.96V. The other E5052A I have some access to shows 2.982V to 3.08V and never reports a POT failure.
Thanks in advance for any replies
Jeremy
HP 8660B/86602B developed output stability problem, getting-started suggestion(s) request

 

My HP 8660B/86602B (owned since 1995 - I've owned it longer than it's initial life in industry, I believe) failed to produce a stable output signal when powered up a few days ago (it has worked properly over the years, although it's use is not frequent.) I wish to tackle repair (at least as a learning experience.)

When tested today at some spot CW frequencies (1, 2, 5, 10, 20, 30, 50 and 100 MHz), output signal is below nominal by 200-300 kHz and is not stable (movement around carrier seen on spectrum analyzer display and listing on a receiver yields a noisy and unstable signal.) A swap-out of the 86602B RF plug-in (I have a spare) yielded no difference in behavior.

I have original operator/service manuals for the three key components (the 8660B, 86602B and 11661B frequency extension module inside the 8660B) and associated extension cables/boards (the 11672 service kit and 08660-60070 extender card set), so at least not flying totally blind.

My getting-started question is from this observation:

The 8660B manual's adjustment/test procedures don't mention whether the 11661B frequency extension module's behavior should be considered (as far as I can see, there is no mention of the 11661B in the 8660B manual at all.) It appears to be silent as to whether the 8660B should be evaluated with the 11661B installed (or not.) The 11661B manual focuses on that device and presumably assumes that the 8660B containing it is working normally.

Where (at the 8660B itself or the 11661B FEM) should I start troubleshooting?

Thanks for any suggestions (other than recycling the hardware and replacing it with a TinySA or similar)!
E5052A Power On Test (3.3V Bus Supply)

 

I wonder if anyone here has experience or access to an Agilent E5052A signal source analyser? Mine is about 20 years old and is recently showing signs of unreliability.
The main symptom is an occasional power on self test fail and it then reports issues with a 3V3 power supply voltage on the A3 DSP/ADC board where it reads low at typically 2.96V. I think a pass requires >2.96V but this may be firmware dependent. My E5052A is running the latest firmware V2.51.

I think this 3V3 supply is common across the backplane but it gets reported as an A3 test in the service menu. The 5V PSU rail also reads low at between 4.7 and 4.8V but this is still a pass (shows true for the test result)
Also, for several years now it has shown a stubborn internal spurious at 60 kHz at a very low level. This very slightly spoils any phase noise measurements even though it shows up at about -140dBc then the trace is in phase noise mode in dBc/Hz. I'm not sure what causes this internal 60 kHz term, it may be from a PSU or the display or a divided clock. It may be that the 60kHz spurious term is a feature of this analyser as it is present on all my plots dating back over 13 years. It's not caused by anything nearby to the instrument as it does it regardless of position or proximity to other equipment. Plus the other E5052A I've used in the past (in a different location) is exactly the same.

The 60kHz spurious is also present when I swap across to the baseband input even with a very clean LF signal fed to the 0-40 MHz baseband input. So this spurious must be getting in at the ADC if it affects the baseband input as well.
?
I've seen similar on another E5052A that also shows a lowish 3V3 voltage (but it never shows a power on test failure) and it also has the permanent 60 kHz spurious on all phase noise tests on the main RF input.
?
The service menu password is only three characters long and is 'kid'
?
If anyone has access to a healthy E5052A could they enter the service menu and do a manual Power On Test (POT) in the service menus? Then report the 5V and 3.3V results for the A3 module
Mine shows anything from 2.91V to 3.05V and I think the pass/fail threshold for the POT is somewhere around 2.96V. The other E5052A I have some access to shows 2.982V to 3.08V and never reports a POT failure.
Thanks in advance for any replies
Jeremy
Re: Accurately measuring 1000pF and 100pF capacitors, to calibrate 4276A?

 

I use a Boonton 76-3A precision decade capacitor for my calibration checks. I originally picked it up for calibration of an old Boonton 72BD meter (0.001 to 2000 pF capacitance range) but it now also serves as a good calibration check on a few HP units that I have. It has capacitance selection from 1 to 1221 pF in 1-2-3-5 x1, x10 & x100 ranges. Accuracy is 0.1% ±0.001 pF. The connections are made through special BNC(M) connectors without outer bayonet shell. But the unit can occasionally can be found in used condition with the Boonton output connector adapter to normal BNC(F) interface or you can make your own.

They sometimes come up pretty inexpensive on ePay amidst the real price gougers.

Greg
Re: Accurately measuring 1000pF and 100pF capacitors, to calibrate 4276A?

 

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If you need accurate measurements, I do have an Andeen-Hagerling 2500E which can measure C @1kHz to better than 5ppm and 8 digits resolution even at 10pF.? I rarely get it calibrated but its still the best on the market.
If you decide on what you're going to use as a standard, I'd be glad to measure it for you if you send your standard to me.
Richard

From: [email protected] <[email protected]> on behalf of Robert G8RPI via groups.io <robert8rpi@...>
Sent: Monday, February 24, 2025 2:28 AM
To: [email protected] <[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] Accurately measuring 1000pF and 100pF capacitors, to calibrate 4276A?
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A General Radio 1422D dual range variable would meet the specification. Needs the calbration chart though. The earlier 722D would be OK if calibrated and used at same temperature.
Not many units neet this specification. A pair of IET SCAs would do but they are not cheap. chaeapest would be to make up something as close as can with PC caps and get it measured. That's the difficult part. Most labs can't measure 100pF to 0.01%.
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Robert.
CRT unit for 8593A compatible

 

I have a 8593A with a display problem.

There is a spare offered, HP 2090-0514 "for 859x E"

question here: is this full compatible and useful in my 8593A?

thank you
Re: 8753C VNA option upgrade

 

Jinxie,
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That keyword text is obviously what I wrote to you at some point.? Anyone with an 8753/8752/871x/8720/8719/8722/8702 can write to me (with the s/n) and get the keywords they need to enable any option.? This is a service I provide for free so that no one has to run the risk of unsoldering and programming EEPROMs.
I have been doing this for almost 10 years now and get a request about once or twice per week.
CV
Re: HP54502A Oscilloscope fail A/D test and cal

 

Fail code 0000 0000 0101 1110
Re: 8753C VNA option upgrade

 

Hi Jinxie,
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Thank you very much for replying. I am currently in the process of attempting the upgrades: I did receive some feedback on the subject - I just need to ensure that I take the time to properly understand the procedure first.
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Thanks again for considering the request
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Kind regards
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