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Re: 4195A restoration adventure*

 

There is a DAC in one of the units which is known to fail. I need to look it up for you, afaik on mikrocontroller net and eevblog there was discussion of
3497A semantics question

 

The photo shows the relevant portion of the Inguard circuit.

It appears to me that if I disconnect and short the voltmeter inputs at J9 & J11 and remove E1 I should have the relay boards feeding the back panel banana jacks which I can connect to my 3457A.

Does jumper J3 set to no A/D allow directing the 100 inputs from the 3497A to an external meter?

Goal is to select a channel with the 3497A and measure with a 3457A. If that goes well I may well spring for a 3458A.

I have a 3457A which will give 7.5 digits. I have in mind measuring 80 or so voltage references over a multiyear period along with temperature control and logging.

This is motivated by volt and time nuts posting plots accompanied by unsupported claims, but refusing to provide the digits for independent analysis . All I've asked for is a chance to be proven wrong without having to wait for years to record my own data. After 10 years of asking I'm going to collect my own data. Simply put, I am a reflection seismologist. We invented DSP in the 1950s (search for " MIT Geophysical analysis Group under Norbert Weiner" for proof).

Reg

3497A-inguard.png

Re: Wanted: WORKING 8482A Power Sensor

 

Well... aren't most people?
There are still a few 8482As left, that haven't had their measuring thermocouple vaporized an shot into outer space... by people who don't know what a milliwat or a dBm is.
What's reasonable?
One time... a long time now... used ones... but not terribly abused to death... they were 'reasonably' price... but dwindling numbers of 'good' ones has seem to made the unreasonable reasonable.
And what's working?
IMO... there's more to it than just getting one the power meter recognizes, zeros and gives a reading.
It seems to me... there ought to be more of them in Japan, than over hear. (Hoarding them, and trying to corner the market, for sale on Ebay, seems more of a thing here.)
Re: File /HP , Agilent Firmware & Programs/KeyCodeGenerator.7z uploaded #file-notice

 

Hello Mr Flanagan,
Thanks for this wonderful tool.
I could activate the LAN option on my 8711C.






Perhaps I will try to update the firmware in the near future.

Bruno Torremans
Re: HP 3490a Multimeter shows all 2s.

 

Hi Alan,

Would you ship it down under (Australia)? I'm curious enough to see if it could be resurrected.

Regards,

Waz
Re: Cheap and simple OXCOs upgrades on ebay

 

Okay, here's some stuff to nudge us back on topic...

One of the two boards I bought from sz.plaza.com had a defective regulator, and I cooked the OCXO before I realized the problem. So I decapitated it and took a photo of the PCB, top and bottom. Images here:?OCXO Photos?

The second board was modified to increase the tuning adjustment range, R3 changed from 36k to 4.99k, and ?1meg resistor brought out from the R2, R3 junction to the ?+/- 5V control voltage of my vintage Symmetricom GPSDO. I placed some foam insulation around the OCXO case, and after a day or two of stabilization I am seeing offsets in the E-11 to E-12 range. The temperature setpoint appears to be 50C

I've run the rest of my stock against the GPSDO to see where the control voltages are now with aging.

Serial # ? ? Voltage
130802 ? ? 1.7052
131221 ? ? 1.8515
140121 ? ? 1.8662
140310 ? ? 1.8366
140610 ? ? 1.9876

Yet to do, is capture the statistics out of the GPSDO to see if there is either a diurnal phase shift, or some slow oscillation in the servo loop.

More as it happens...

Dave?
KC6UPS
Added Folder /A temporary directory for photographs and help relating to emails and posting/CTI_OCXO internal photos #file-notice

Group Notification
 

Dave Wright <davewrightsplace@...> added folder /A temporary directory for photographs and help relating to emails and posting/CTI_OCXO internal photos
Re: Another 3GHz 53132-68003 Chanel 3 option design for the 53131A and 53132A

 

On straightening the traces, I wonder if rotating the parts (and 45 degrees is legal) would help.? Don't think that power leads are as critical.? IIRC, the bends might cause impedance changes and therefore reflections, but someone who actually does this might want to comment.

From what I remember about waveguides (seeing them), the minimum bend radius is frequency related, too.

Harvey

On 11/1/2023 12:03 PM, Jared Cabot via groups.io wrote:

The diodes are there because that's what HP did. I would also like to know the exact reason they did that too. :) It seems to work, so I'm sure there's a good reason for that layout.


The Coplanar waveguide specs are as follows:
PCB thickness = 1.6mm
Conductor width = 1.5mm
Conductor gap = 0.28mm
So that makes the trace Impedance = 50.1 ohms according to the Saturn PCB Design Toolkit.

Is there a benefit to going to a thinner board for signal integrity etc? I designed around 1.6mm thickness as it's the most common size (so cheapest, easiest, and quickest to get from China).


I'll have a go at straightening those traces too.
HP 3490a Multimeter shows all 2s.

Alan Kilian
 

I got a bunch of stuff from an old moldy garage for US$50 a box and this HP 3490A shows all number 2 on the display.

It looks (to me) to be in pretty rough shape externally, and great shape internally, but before I give up on it, I'm offering it here if it or parts of it are useful to you.

Photos are at:

I can take measurements/scope traces etc. of various places and perform experiments if it will help understand what shape the meter is in.

If anyone wants the whole thing or parts of it for $50 plus shipping from US area code 02138, it's all yours.

If it turns out not to be useful, I'll keep just the display and face plate and repurpose them into some art project or other.
Re: Another 3GHz 53132-68003 Chanel 3 option design for the 53131A and 53132A

 

Straight signal line, 2 layer, (transistors.....), bottom ground plane stitched to top ground pour.

Yep, looks reasonable to me.

Harvey

On 11/2/2023 1:09 AM, Jared Cabot via groups.io wrote:
Here's some pictures of the original HP board that I found online:

HP 53132-60003 PCB Top <>

HP 53132-60003 PCB Bottom <>



Jared
Re: HP8753 error, "CAUTION: NO IF FOUND: CHECK R INPUT LEVEL"

 

¿ªÔÆÌåÓý

Hej Klaus det er desv?rre ikke s? let. Du kan kun k?re med intern source. Og der er 2 slags YIG i de apparater. 5086-7473 eller 5086-7934. De g?r begge i stykker. Du kan god f? den repareret men du skal regne med 4000-5000 for det.?
Eller se efter en 8753 som er hugget op.
mvh Peter

Fra: [email protected] <[email protected]> p? vegne af kvk@... <kvk@...>
Sendt: 2. november 2023 08:29
Til: [email protected] <[email protected]>
Emne: [HP-Agilent-Keysight-equipment] HP8753 error, "CAUTION: NO IF FOUND: CHECK R INPUT LEVEL"
?
Hi

I have an HP8753 network analyzer I bought at an auction.

When powered up, it shows the error: "CAUTION: NO IF FOUND: CHECK R INPUT LEVEL"

Seems the 8753ES has a known problem with YIG oscillator:
?
/g/HP-Agilent-Keysight-equipment/topic/hp_8753c_caution_no_if/82863730?p=,,,20,0,0,0::recentpostdate%2Fsticky,,,20,2,0,82863730
?
https://www.eevblog.com/forum/repair/hp-5086-7781-yig-oscillator-tear-down-fits-85628563a-sa/
So I need that fixed.

Could I buy an external clock to solve this, or maybe find a person that I could pay to repair it for me? (I am based in the EU)

Regards

Klaus

HP8753 error, "CAUTION: NO IF FOUND: CHECK R INPUT LEVEL"

 

Hi

I have an HP8753 network analyzer I bought at an auction.

When powered up, it shows the error: "CAUTION: NO IF FOUND: CHECK R INPUT LEVEL"

Seems the 8753ES has a known problem with YIG oscillator:
?
/g/HP-Agilent-Keysight-equipment/topic/hp_8753c_caution_no_if/82863730?p=,,,20,0,0,0::recentpostdate%2Fsticky,,,20,2,0,82863730
?
https://www.eevblog.com/forum/repair/hp-5086-7781-yig-oscillator-tear-down-fits-85628563a-sa/
So I need that fixed.

Could I buy an external clock to solve this, or maybe find a person that I could pay to repair it for me? (I am based in the EU)

Regards

Klaus
HP85422E frequency offset

 

Hi
?
I recently bought a? EMI test receiver HP 85422E at an auction.
?
I have tested it, directing a single frequency into the RF input.
?
The gain is spot on, at most 0.5dB off. But the frequency is wrong.
If I enter 50MHz, I get 20MHz peak. If I then add 100MHz, it only increased the peak by 73MHz. It's consistent, every time I increase by 100MHz, only 73MHz is seen (generator has been checked on another spectrum analyzer)
?
I guess it works by sweeping a local oscillator, and generating an IF frequency.
?
What could be wrong?

I am looking to repair it, but have no HP repair experience, so I am looking to find someone who I could pay to repair it. I am based in the EU. Anyone know of experienced person doing this??
?
Regards
?
Klaus
Wanted: WORKING 8482A Power Sensor

 

Hi all,

I'm on the hunt for a verified working 8482A power sensor, shipped to Japan.
If you can provide a few pictures of it in operation and are willing to sell it for a reasonable price, I'm interested. :)

I can pay via paypal.


Thanks!
Jared
Re: Another 3GHz 53132-68003 Chanel 3 option design for the 53131A and 53132A

 

Here's some pictures of the original HP board that I found online:







Jared
Re: GPIB Control / Data Software for 8720A VNA?

 

It's pretty straight forward.


I take the four real/imaginary S-parameter data pairs, using the Smith plot data retrieved by HPIB and write the data to a flat file.
See?
https://github.com/VK2BEA/HP8753-Companion/blob/12d9ad4fbc591d4baea50103171d705a5d26497c/src/HP8753_S2P.c
https://github.com/VK2BEA/HP8753-Companion/blob/12d9ad4fbc591d4baea50103171d705a5d26497c/src/messageEvent.c#L114
Re: Another 3GHz 53132-68003 Chanel 3 option design for the 53131A and 53132A

 

Good point Tom. The schematics don't necessarily indicate the fine details of circuit structure (especially at HF) and operation. I guess there is no picture of the original HP board layout? If one is available, it would help a lot.

Ed
Re: Another 3GHz 53132-68003 Chanel 3 option design for the 53131A and 53132A

 

I don't know what HP's original layout looks like, but here's one possibility for the doubled-up diode clamps: Note that they're not directly in parallel -- they're separated by other stuff. If that other stuff is intentionally made to look like a segment of slightly higher impedance line (and therefore inductive), then the diode capacitance gets more or less absorbed into the T-line, rather than looking like a lumped capacitive load. That way, you can get substantially better protection without killing bandwidth or SWR.

Don't know if that was HP's reason, but I've used similar protection strategies in a lot of designs. It's hard to get good ESD withstand at mm-wave freqs without doing something like this.

-- Cheers
Tom

On 11/1/2023 9:03 AM, Jared Cabot via groups.io wrote:

The diodes are there because that's what HP did. I would also like to know the exact reason they did that too. :) It seems to work, so I'm sure there's a good reason for that layout.
Re: Another 3GHz 53132-68003 Chanel 3 option design for the 53131A and 53132A

 

Jared, as I recall, the modern replacement diodes you're using are quite a bit more stout than the originals HP used. The only reasons I can picture for the doubled-up ones by HP is first, at the input, to handle some input RF overload protection level spec. Any ones deeper into the circuit could be limiting to protect the individual amplifier stage IC inputs at various points - I don't know what their specs are, but if they can output much more than the next stage's input rating, this could be an issue, requiring some diode clamping. The diodes can help to provide some degree of leveling too, but only where the level is already high enough to activate them. This would tend to flatten the overall frequency response, at least at high input levels.

Depending on your diode ratings versus the original, you can probably eliminate the double-ups, and the associated extra capacitance, which should speed things up.

Good luck. I know you'll make it work.

Ed
GPIB Control / Data Software for 8720A VNA?

 

Hello again Group -
I have an 8720C and would like to be able to extract s2p files.
I do have a PC with GPIB, and also I have a plotter emulator which works great.
But I need a way to extract the data files.
Either free or up to maybe $1k - any suggestions?

Thanks
Dan
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