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3708A Noise and Interference Test Set - Looking for a Service Manual

 

Hi,
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I just pulled my 3708A off the shelf for a bit of a spit polish ready to sell it off and I'm looking for a service manual for the performance test and calibration procedures.
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I can't seem to find anything but the Operating Manual in the usual places.
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Does anyone have a digital copy of the service manual for this instrument?
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Thanks!
Jared
Re: HP Agilent 8753ES VNA repair [Help]

 

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Hi,

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Starting point VCXO are correct frequency with 40.000MHz.

At TP20 you have a frequency of 39.100MHz, and at the output of divider 40 you get 977.5kHz. This indicates, that the divider by 40 is correct but the frequency is wrong from VCO.

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At output of mixer 40MHZ from VCXO is mixed with 39.100 MHz (>16 MHz?) to have around 900kHz (909kHz).

At output of mixer 40MHZ from VCXO is mixed with 39.280 MHz (< 16 MHz) you will have around 720kHz.

Mixer is OK, but bad frequency from VCO, and good frequency from VCXO.

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Phase detector received bad feedback frequency from VCO (example for HIGH band, 909kHz instead 160kHz)… The PLL is open loop for a reason unknown at this time.

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Correction: TP6 is a TP from output mixer (H160kHz, L=4kHz), and TP7 is the reference for PLL (40MHz from VCXO divided by 250 for HIGH BAND and divided by 10,000 to have 4kHz).

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First question: Is the reference coming from the VCXO divided to have 160kHz for the high band and 4kHz for the low band correct at TP7?

The VCO is functional, but the frequencies are incorrect, can the VCO range cover the expected frequency band, between 39.84 and 39.996 MHz.

The electrical schematic shows the PLL section of an 8753D, which should be quite similar if not identical for the 8753ES.

A way to test the VCO range should be found…remove serial resistor near the TP to inject DC voltage.

But this verification can wait, and the verification of the phase detector and especially the integrator are the next points.

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I must go, come back later today.

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De?: [email protected] <[email protected]> De la part de MattSNE via groups.io
贰苍惫辞测é?: 2 mars 2025 05:48
??: [email protected]
Objet?: Re: [HP-Agilent-Keysight-equipment] HP Agilent 8753ES VNA repair [Help]

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Hello Yves,

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Thank you for your last post.?

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My VCO frequencies in TP20 are not correct. I have :

- a RF signal is at 39.100 MHz, -1.3 dBm instead of 39.840 on your board for frequency >16 MHz?

- a RF signal is at 39.280 MHz, -1.3 dBm ?for frequency <16 MHz?

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The 2sd LO is at 977 instead of 996 this is why my sampler FI output is at 23 MHz instead of 4 KHz.

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My VCXO is at 40.000 precisely. The VCO output to the mixer do not correctly converts the signal to L=4kHz and H=160kHz from what I measure. I have a signal at 909 KHz here.

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On PIN 2 on the divider output : 39.100 MHz divide by 40 : 977 KHz. -> The 2sd LO frequency I measure. ?

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Re: Service manual scan post processing

 

On Sun, 2 Mar 2025 at 16:25, Bert via <el_bert0=[email protected]> wrote:
The one thing with image cleanup routines, they are mostly made for text based documents and are looking to clean up the text. As such, they don't have the "understanding" as to the particularities of schematics.? In the way back days, there was vectorizing tools to help engineering firms convert scanned drawings, those things on dead, ground up trees to CAD files. But they required both a lot of work to verify the exactitude of the resulting CAD file and possibly re-verify and re-authorize it.

A very useful amount of cleanup can be done simply by comparing each pixel on its own to the average of the wide neighbourhood pixels. That works equally well for text and schematics, since it has no concept of either and they are both high contrast. It does not work well with photos.

How well such text/schematic cleanup works depends on the original's quality. Unsurprisingly, higher XY resolution and uniform illumination/background are advantageous, since both allow the "slicing level" to be more easily determined and more uniformly applicable.

Provided there are sufficient pixels for the text characters to be reasonably well formed (open loops, no "spurs"), OCR is then possible. Evidence: a couple of manuals I have quickly scanned on an ordinary printer/scanner/copier, post processed into TIFFs inside a PDF file, and somebody else has OCRed.

I have no comment about vectorising; I have never had any use for such a tool. I would expect it to be as (un)successful as decompiling binary object code back into a high level language source code.
Re: Service manual scan post processing

 

On 3/2/25 11:25, Bert via groups.io wrote:
While we seem to all agree that JPEG compression is not ideal, there ARE lossless options for TIFF and thus PDF formats.
At the museum, we use ITU-T T.6 (Group 4 FAX), which is lossless and very effective.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA
Re: Manual for HP 466A amplifier

 

On 3/1/25 23:06, Jeremy Nichols via groups.io wrote:
Paper original will be sent to Dave McGuire on Monday.
I don't mind getting it scanned at the museum, but does it still make sense to do that after the revelation that Artek has it available? I hadn't checked before; I had assumed the OP had already done so.

-Dave

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Dave McGuire, AK4HZ
New Kensington, PA
Re: Manual for HP 466A amplifier

 

On 3/1/25 08:45, Jeremy Nichols via groups.io wrote:
I have a paper copy of the HP-466A manual, serial prefix 226, and could copy the schematic for you.
I've got one of those amps and would like the schematic also.

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John Griessen
Re: Service manual scan post processing

 

While we seem to all agree that JPEG compression is not ideal, there ARE lossless options for TIFF and thus PDF formats.? While yes, storage and networking and processing and scanning time is all relatively cheap, when someone is paying all that on their own dime, there are decisions to be made.
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Where I come from, the rule for text-ish documents is 300 B&W and for image-ish it's 200 @256, and this for financial, governmental types.
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The one thing with image cleanup routines, they are mostly made for text based documents and are looking to clean up the text. As such, they don't have the "understanding" as to the particularities of schematics.? In the way back days, there was vectorizing tools to help engineering firms convert scanned drawings, those things on dead, ground up trees to CAD files. But they required both a lot of work to verify the exactitude of the resulting CAD file and possibly re-verify and re-authorize it.?
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The basic rule here is that you can clean up or otherwisely "alter" a document as long as the understanding does not change.

Re: HP 3403C True RMS Voltmeter display fault

 

On 3/2/25 09:06, factory via groups.io wrote:
The manual on the web gives type 150D for C1 & C2 on A7, these are hermetic sealed solid tants, of course they might have been replaced with a bead or the disguised bead in an axial or radial block package in the past, or HP (or someone else) might have decided to use the non-hermetic axial ones in a repair, or later build using them.
Yes, that's why I wanted to see a picture. I've never seen the ball-of-molten-tantalum failure on anything other than a dipped unit.

And I notice they are listed as 15V parts on 12V rails, not much derating, if using non-hermetic tants make sure to use at least double the voltage rating for replacements.
Seconded.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA
Re: HP 3403C True RMS Voltmeter display fault

 

The manual on the web gives type 150D for C1 & C2 on A7, these are hermetic sealed solid tants, of course they might have been replaced with a bead or the disguised bead in an axial or radial block package in the past, or HP (or someone else) might have decided to use the non-hermetic axial ones in a repair, or later build using them.
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And I notice they are listed as 15V parts on 12V rails, not much derating, if using non-hermetic tants make sure to use at least double the voltage rating for replacements.
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David
Re: E5052A Power On Test (3.3V Bus Supply)

 

I don't know if this helps, but I dug out the most recent Keysight calibration certificate for this E5052A and there is a noise floor test done at 70 MHz with correlation set to 1.
I'm not sure what is involved with this test or at what power level it is run at but the numbers for the noise floor seem to be very good! I don't have anything here that can replicate this test although I could probably design a low noise LC oscillator that could get close at a 1 MHz offset.
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I generally design wideband single loop synthesisers up at VHF through UHF and the E5052A is easily good enough for stuff like this.
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Re: HP Agilent 8753ES VNA repair [Help]

 

For reference list of the component I have on the A12 board:
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- 10H116 : Triple line receiver?
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- LM6321: high speed buffer?
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- MC143 : Low power RF mixer?
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- AD7545 : CMOS multiplying DAC
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- AD847 : AOP
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-OP37 : AOP
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- PH2222A: NPT transistor?
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- TL071C: AOP
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- 78M05 : 5V 1A LDO
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-DG408 : CMOS multiplexer
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-HC273A: CMOS gate flip-flop
Re: Agilent MSO6014A Not Booting

 

This is a long shot (and I know nothings about this particular piece of equiptment), but here goes: I have an Agilent N5030A which was not booting.? I changed the battery on the mother board (and again not booting).? But there was a "switch" on the PCB (i.e. two pins on the PCB) next to the backup battery which one had to short out (labeled "reset").? This forced the card to boot from the RAM rather than the hard disk drive and allowed it to start up fresh after the said battery change.? Perhaps there is a backup battery on the CPU board that you could remove, replace, and a similar switch which one could short to force it to boot up and reset in this manner???? Total long-shot, so please ignore if not helpful.
Re: E5052A Power On Test (3.3V Bus Supply)

 

-120dBc/Hz at 1 Hz is way better than anything I've experienced. I had a look at a plot of my homebrew oscillator and it managed -116dBc/Hz at 10 Hz.? Pretty lame by comparison...
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I guess you are aware of the Jeremy Everard paper from the University of York. This describes a 10 MHz ultra low noise oscillator that achieves -122dBc/Hz at 1 Hz offset.
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They used a Symmetricom 5120A as below. Very impressive! I don't think the E5052A can get anywhere near this level of performance.
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Re: HP Agilent 8753ES VNA repair [Help]

 

On TP20 I have a RF signal is at 39.280 MHz, -1.3 dBm ?for frequency <16 MHz instead of 39,996 MHz ?--> Delta is 716 KHz
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On TP14 for a 10MHz setting on the VNA I have a 2sd LO frequency at 10.720 MHz instead of 10 MHz --> same delta?
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From what I understand The 2sd LO in low and high band is not correct because my VCO is not at the correct frequency.?
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Now we need to understand why :)?
Re: E5052A Power On Test (3.3V Bus Supply)

 

Hi Leo
This E5052A is quite old now and it does have a few internal spurious terms. Also the noise floor performance isn't that great even down at 10 MHz.
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I don't have any oscillators here that can generate really low phase noise close to carrier. A few years ago I designed a 10 MHz crystal oscillator with low phase noise but I think it only managed a noise floor of about -173dBc/Hz from 10 kHz onwards. This was the theoretical noise floor of the oscillator (at least according to my basic calculations) but I don't think I've ever seen -180dBc/Hz even with lots of correlation. I've never used more that 100 for the correlation setting though.
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I'm fairly certain the E5052A just uses an external reference to discipline the internal reference. Both of the E5052A analysers that I have used have an internal high stability OCXO mounted inside the chassis and this has its own output at the rear panel. The idea is to link it to the REF IN connector with a short BNC-BNC jumper and then it shows up as an external reference even though it is actually inside the chassis. My E5071B VNA uses a similar system for the OCXO option.
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If this BNC-BNC link is removed then the E5052A uses the main 10 MHz oscillator inside and the OCXO is ignored.
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The best thing about the E5052A is that it is very fast. What isn't so good is the qty of internal spurious terms, especially the one from the backlight at 60 kHz. I don't think it can compete with modern alternatives in terms of the noise floor it can achieve. The E5052B is going to be better I think. Hopefully the internal spurious are improved on the E5052B as well.
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The baseband input of the E5052A is normally locked out in software with no mention in the documents how to unlock it. I think Agilent decided to hide this feature, probably because of the internal spurious that spoil the performance and also the noise floor rises a fair bit at low frequencies. There is also an enhanced jitter option which I've played with but I don't have much need for stuff like that. The jitter option is documented and available but the baseband isn't. I had to hack inside the firmware of this E5052A to find out how to release the baseband option. It can't be done via the option menus in the way the jitter option can be unlocked.
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If you look on Eevblog, I'm currently testing one of your LBE-1421 GPSDOs.? I'm getting the same result for phase noise that you did. I'm G0HZU on Eevblog.
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Regards
Jeremy
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Re: HP Agilent 8753ES VNA repair [Help]

 

Hello Yves,
?
Thank you for your last post.?
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My VCO frequencies in TP20 are not correct. I have :
- a RF signal is at 39.100 MHz, -1.3 dBm instead of 39.840 on your board for frequency >16 MHz?
- a RF signal is at 39.280 MHz, -1.3 dBm ?for frequency <16 MHz?
?
On PIN 2 on the divider output : 39.100 MHz divide by 40 : 977 KHz. -> The 2sd LO frequency I measure. ?
?
The 2sd LO is at 977 KHz instead of 996 KHz this is why my sampler FI output is at 23 KHz instead of 4 KHz.
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My VCXO is at 40.000 precisely. The VCO output to the mixer do not correctly converts the signal to L=4kHz and H=160kHz from what I measure. I have a signal at 909 KHz here.
Re: HP Agilent 8753ES VNA repair [Help]

 

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There are contradictions in the test results:

If you say that the VCO frequencies are correct (39.996MHz for LOW and 39.84Mz for HIGH), then this necessarily means that the VCXO is at precisely 40 MHz, that the divider L=4kHz and H=160kHz are functional, that the PLL is working, that the VCO output to the mixer correctly converts the signal to L=4kHz and H=160kHz, that the PLL loop is closed and stable. But the divider by 40 could be faulty if you don't have always 996kHz for HIGH at PIN2.

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You say you don't have the correct 4KHz or 160KHz at output divider (909 KHz output instead of 160 KHz).

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My error TP14, 10.4MHz it’s not good, its 10.004MHz. Marker was OK , added text have error on picture.

You have 10.4MHz to TP14 for 10MHz setup, it’s bad.

In this case A14 have problem if TP20 have for high band VCO must be 39.84Mz and VCO at 39.996MHz for lowband <16MHz.

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Need to know if the frequencies are OK for TP20.

I'll look at all that again tomorrow.

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Yves
Re: HP Agilent 8753ES VNA repair [Help]

 

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De?: [email protected] <[email protected]> De la part de MattSNE via groups.io
贰苍惫辞测é?: 2 mars 2025 03:07
??: [email protected]
Objet?: Re: [HP-Agilent-Keysight-equipment] HP Agilent 8753ES VNA repair [Help]

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Is the test point on the picture correct ??

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8510C/8530A Surplus units (UK)

 

Hi,
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I have accumulated quite a bit of 8530A/8510C stuff over the years. the 8530A stuff? I was going to use to experiment with an antenna range. Realistically it's never going to happen, and all the (heavy) boxes are taking up space at home. I'm looking at letting some of it go if anybody here might be interested.
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85101C Display unit (with 3 PAL chips) and the 8530A firmware loaded.?
8530A microwave receiver
8511A Frequency Convertor
8514B S-Parameter test set
Interconnect Cables x2?
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Also got some spares or repair units
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85101C display unit
8510C? Microwave Receiver
8514B S-Parameter test set
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Due to the size and weight I wouldn't be interested in packing and shipping these, so collection only really And ideally looking to offload as job lots rather than individually.? I'm based in the Midlands (UK), I don't mind travelling a little way to meet someone halfway or deliver them.?
Re: E5052A Power On Test (3.3V Bus Supply)

 

Hi Jeremy,
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This is a great win. What is your overall impression of the E5052A?
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I have R& FSPN8 and 53100A but I would like something I can try to push to lower phase noise levels. I need below -120dBc/Hz at 1Hz and below -180 far out.
FSPN8 gets there but very slowly as its references are not ultra low noise level class. And it does not allow to use external references like 53100A or 5052A.
53100A is OK but has some spurs I can't get rid of and I also like all-in-one instruments.
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If you were to stick ULN Wenzels or comparable references on 5052A would you reliably get below -120dB @ 1Hz and -180 far out?
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Thanks
Leo
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