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

 

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.
Re: VNA cal kit manager and Prologix GPIB?

 

I use the cal kit manager to create the XML version of the cal kit.
In my '' program for the 8753 I parse the XML and use the relevant HPIB commands to send it to the analyzer. From memory the 8510 commands are the same.
See ...?
and?
I'm using the Linux GPIB driver (which I don't think works with the Prologix device) but I'm sure you have an environment that does.
Re: VNA cal kit manager and Prologix GPIB?

 

On Wed, 1 Nov 2023 at 12:49, tom_iphi via <iphi=arcor.de@groups.io> wrote:
Hi all,

I have just stumbled across the VNA cal kit manager software here on this site:
/g/HP-Agilent-Keysight-equipment/files/VNA%20Calibration%20Kit%20Software/VNA%20cal%20kit%20manager.exe
This appears very useful!
Does anybody know if it can be used in combination with the Prologix GPIB USB adapter to transfer cal data to the 8510C?

Tom

My understanding is that it only works with NI or Agilent GPIB cards, but I have not verified that.

VNA cal kit manager and Prologix GPIB?

 

Hi all,

I have just stumbled across the VNA cal kit manager software here on this site:
/g/HP-Agilent-Keysight-equipment/files/VNA%20Calibration%20Kit%20Software/VNA%20cal%20kit%20manager.exe
This appears very useful!
Does anybody know if it can be used in combination with the Prologix GPIB USB adapter to transfer cal data to the 8510C?

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

 

Why two sets of diodes before the prescaler?
I would think that two diodes after the resistor should be enough.
The pair after the amplifier have no limiting.
Also agree with the comment about straightening out the traces on the amplifiers.
A question, are you using a 0.032 (0.8mm) thick board or other thickness than 0.062?

ed
Re: help repairing 8133a

 

开云体育

Hi,

?

One problem to solve, the next one will be a little more complicated, namely the timing board.

?

For my part, I also ordered an RF relay which I received last week, and it works perfectly.

I will replace it anyway even if I managed to repair the original in the 8133A.

?

?

Regards

De?: HP-Agilent-Keysight-equipment@groups.io <HP-Agilent-Keysight-equipment@groups.io> De la part de Xtremexp
贰苍惫辞测é?: 31 octobre 2023 11:27
??: HP-Agilent-Keysight-equipment@groups.io
Objet?: Re: [HP-Agilent-Keysight-equipment] help repairing 8133a

?

Hi Yves,

Today I received the RF relay and I managed to replaced the faulty one. Indeed the RF relay was bad as you can see the transmission losses observed using VNA (my VNA can only goes up to 3Ghz). After replacing relay, the channel 2 positive output works.
RF Relay transmission loss:


New Relay Transmission loss:


Here are more pictures:



---------------
On the clock frequency issue, I do not think I will receive the timing board. it's stuck in transit. I do not have any path forward to debug or repair of the clock.?

Regards,
?

RF relay 8133A.png

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

 

The MB510 should give more predictable results, having much more uniform frequency response than the UPB1506.

If tweaking bias and input frequency response tricks just don't cut it even with the MB506, and you must have no output (can't just ignore it) when there's no input signal, there is another option. This would entail having an RF signal level detector in the amplifier chain, and a comparator circuit that overrides the prescaler's bias so it can't respond unless the detector says there's enough input level to work right. The prescaler can then be run in stock mode, with maximum sensitivity, whenever it's enabled. This of course adds another set of considerations like what trip limits apply, and how accurately it all must be determined, and the added circuit complexity.

HP apparently got the original system to work adequately to avoid this nuisance response (right?), and meet some sort of specs - I'm not familiar with this model so don't know if these are true. Anyway, if they did, then you can too, but with the grief of having to use some different parts. I doubt that the original is extremely clean and flat and totally free of instabilities, but just enough for whatever the specs are.

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

 

Would it be a better layout if U1 and U2 were rotated to straighten out the traces?? No idea, but it's something that occurs just by looking at it.

Harvey

On 10/31/2023 1:37 PM, Jared Cabot via groups.io wrote:
And just for funsies, here's the latest layout, using the MB510-PF chip and HP designed bias network as per the HP original design.

Let em know if there are any glaring errors. :)




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

 

And just for funsies, here's the latest layout, using the MB510-PF chip and HP designed bias network as per the HP original design.

Let em know if there are any glaring errors. :)




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

 

My spectrum analyser is a Siglent SVA1032X, good for 3.2 GHz.
I'll have to get a down converter for my scope...

It's all SMD (I even mounted the resistors upside down to improve performance) and the entire signal path is 'coplanar waveguide with ground' at almost exactly 50ohms.


I haven't completely given up just yet, but I took the cheater's way out... I just ordered some MB510-PF prescalers from China, the same part that HP used. :D
I'll replicate the HP bias network, with the only main differences in my design being the 5V LDO regulator rather than a zener regulator, and the RF amps/diodes being substituted too as they are obsolete and my selections all seem to work fine.


I have just re-laid out the PCB for the new prescaler, so once I've slept overnight and looked at it again tomorrow with fresh eyes and fixed any stupid mistakes, I'll send the gerbers off to get the PCB's made and wait for the prescaler chips to come from China.
At least if I get a closer replica working to HP specs with a HP specified prescaler, I can use that as a baseline for further tweaking if needed.



One other question. I'm not sure if I'm doing it right, but I tried measuring the SWR of the input using the SWR function of my VNA for fun. Does this look correct/reasonable/etc or does SWR not matter for this application? I'm still learning what I'm looking at here..










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

 

On Sun, Oct 29, 2023 at 04:15 PM, Jared Cabot wrote:
Unfortunately the highest bandwidth scope I have is a TDS794D at 2GHz, so it's a little hard to scope the input to the prescaler directly to see what's going on. Any ideas on how to see the signal level there?
I guess you don't have a wider spectrum analyzer?

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

 

Am 29.10.2023 um 16:15 schrieb Jared Cabot via groups.io:
Unfortunately the highest bandwidth scope I have is a TDS794D at 2GHz, so it's a little hard to scope the input to the prescaler directly to see what's going on. Any ideas on how to see the signal level there?
Use a down converter. If you have a -hp- 5257A Transfer Oscillator or similar, you can use that to downsample the HF to below 100MHz.

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

 

Are the two input chips identical?

Is it reasonable to expect the two chips to behave similarly if different?

Could it be that adding the resistors somehow adds enough capacitance to mess up the frequency response?

You're using surface mount resistors, right?

resonant circuits anywhere?

How is the prescaler driven?? Could that make a difference?

I am NOT an RF type, but there might be some validity here.

Harvey

On 10/31/2023 12:19 PM, Jared Cabot via groups.io wrote:
Hmm, I'm getting to the point I'm going to give up on this now. I've spent too much time chasing my tail and I'm just not smart enough to figure it out.


I can get it to respond from 20 MHz up to 3.2 GHz without any input bias and it operates fine (if a bit deaf compared to the HP design, as per my previous messages), but then it has that free-running thing with no input signal.

If I use any sort of bias on the input (22K bias in the following example, the internal resistance from the input pins to Vcc is 7.5K) the random counts stop but the maximum frequency the prescaler operates to is only 2.4-ish GHz (minimum is still less than 100 MHz, so that's fine), BUT it seems there is some weird behaviour from the prescaler chip.
At a number of frequency ranges (shown below) it outputs roughly double the frequency that it should.... (changing the amount of bias just shifts the problematic frequencies up or down)

190 MHz - 195 MHz
224 MHz - 240 MHz
275 MHz - 305 MHz
350 MHz - 415 MHz
450 MHz - 495 MHz


I just don't know enough to figure this stuff out, so I'm quickly coming to the point of not continuing to waste time and dropping this project.
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