Hi,

Might, or not, be the original parts but you certainly want to look at EDAC connectors:
https://edac.net/

This is a 30p PCB mounted connector, I suggest to measure yours with a caliper and compare. They have several different sizes.
https://www.mouser.be/ProductDetail/EDAC/305-030-500-204?qs=0l4xDpTicHLdB29%2FIhn4uw%3D%3D

Hello, does anyone know where I can find an equivalent of the Agilent 1GM1-4205 IC?
It's an RF switch IC consists of three SPDT switch. It's used on the Agilent ESA spectrum analyzer main RF deck to switch the various inputs, cal signals into the main mixer.
Mine is broken and no longer switch the main input into the main mixer.
Any help is greatly appreciated.

Hi Razvan,

When you have a 5313xA firmware 3403, I think by default the EEPROM includes the configuration for the 3GHz option.
So, only the hardware option would be missing.
When I bought my hp53132A several years ago, I installed the 3GHz option only later.
After installing the PCB, the 53132A worked normally without having to modify the EEPROM or adjust the scale.
Since then, I have acquired another meter, Agilent 53132A (newer, firmware 3944); I transferred the 3GHz option to this one without problems and the frequency displayed was normal, without having to put a compensation scale or modify the EEPROM.
Hence my conclusion that the 3GHz option is activated in the EEPROM by default, but it obviously requires the hardware part to be added.

The 124 option (12.4GHz), the divider is 512 instead of 128 for 3GHz, then you must put a scale of 4, to multiply the result by 4 to display the correct frequency.
By modifying the EEPROM as suggested in the document, I should be able to make the 12.4GHz option work without changing the scale.
It's quite easy to simply activate the scale at 4.

But in my opinion, it may be a lot of work and a risk to remove the EEPROM, put a socket (restricted place on the PCB), and make modifications in the EEPROM.
Furthermore, on the PCB of my hp53132A, I cannot find the R334 resistor cited in the document.
In short, I will look at the implications of making this change, and I will take the opportunity to do a firmware update, if I decide to move forward with this little project.
I need to check the calibration procedure first.

Yves

Envoyé : 6 mai 2024 04:28
? : [email protected]
Objet : Re: [HP-Agilent-Keysight-equipment] Another 3GHz 53132-68003 Chanel 3 option design for the 53131A and 53132A

Hello Yves,

I was thinking the same that something is not right in the firmware.
I found the same thread on EEVblog late last night. For me it is more work to be done since my 53181A and 53132A both have no option so I need to maybe install the zero ohm R334 resistor and also the U14 socket.

When I will have time I will open my counters and check the motherboards first.

Would be great news if you can confirm this info and the cloned 12.4GHz work by default without any scale adjustment.

There is also an 18GHz version from the same seller on eBay and I wonder that one how it would work since HP never had 18GHz version released.
They say you need the 3GHz option already installed and working and after that you need to set scale to 4.0 to have the 18GHz option working correctly. Maybe the hex values modification in firmware tells it what divider or IF to use so maybe other values (or the same values as 12GHz) will make it working fine without scale adjustment.

Thanks,
Razvan

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---

Oh, and yes, the "old hp controller". I started this whole thing because my 85060C cal controller is dying and finding an 85097A is close to impossible.

Hello All,

I have an hp1611A Logic State Analyzer that has two broken 15-pin, 2-row card-edge connector sockets, part number 1251-1886.

Would anyone have some of these sockets so I could fix this motherboard?

Thanks in advance.

Christopher

Thanks, I'm going to consider all diode types from all manufacturers so I'd be happy to use BAT parts if they work OK. I'd welcome any other suggestions as well. I do have an old Avago diode kit here with their whole Schottky diode range in it but this is all in SMD.

I did another test using a decent ESGD sig gen as the source. I used my (SMA) homebrew compensated tee with the far end terminated in a decent 18GHz SMA load. Normally, I would externally level the generator using a power meter and external ALC but in this case, I'm not after great precision (yet). This sig gen is usually well within +/- 0.1dB across this frequency range when using its own internal levelling as long as I pad the output and don't turn the level up too high.

If I test the channel A probe for flatness with my homebrew tee or a homebrew compensated termination I see a gradual upwards slope up to about 500MHz. However, this slope is only about +0.25dB in total. I don't think this is in the sig gen. Some of it will be in my tee and some of it in the probe itself. However, this agrees with my old HP 8405A when I do the same test on its channel A probe.

If I then plug the channel B probe PCB into the channel A probe on the newer HP 8405A, the performance degrades a lot in terms of flatness. It was so disappointing I didn't write down the results but it exceeded 1dB by about 150MHz and hit +2dB by 250MHz.?

So something is clearly wrong with this probe element. I have a fair bit of design experience designing Schottky detectors up to a few GHz and usually when something like this upwards slope happens it will be a function of the input capacitance and any stray package inductance in the overall detector design. This typically causes some peaking up towards UHF. Adding damping resistance can help but this can spoil the input Rp.

I think it could take me a while to find the right diodes to use, but I'm in no hurry as I have the other HP 8405A here and I rarely use it anyway. I want to get this newer HP 8405A working really well, hopefully as good as the older one in terms of probe performance :)

Note that even in its current state I think it would be fine to use up to about 100MHz even with the wrong diodes in the probe. I suspect that the majority of 8405A uses will typically use these meters below 150MHz.

I agree that your measurements are trustworthy and so the diodes are indeed the main suspect.

Dave Wise’s suggestion of a BAT62 is a great one if you don’t mind a breakdown voltage that is a bit less than the spec’d allowable input voltage.

And they’re more readily available than the original through-hole parts.

Tom
Sent from an iThing; please forgive the typos and brevity

I'm using an Agilent E5071B VNA and a decent cal kit and I use the fixture simulator feature in the VNA to correct for the fixture. I normally do this stuff up to many GHz so I think the fixture is fine.
The diode repair/fitment looks fine apart from the fact that the diodes are different.

I'm also measuring the relative differences between healthy probes (they all agree) and the modified probe (shows higher capacitance and poor Rp).

You can see the difference below. Channel B obviously has a problem with input capacitance and the Rp is also degraded up at VHF.

Also, if I do a flatness test across 10MHz through to 300MHz, my old HP 8405A meter and probes agree within <0.3dB up to about 300MHz. This meter hasn't been adjusted in about 10 years so this is a good result I think.

The newer HP 8405A is obviously poorly because the response isn't as flat and the two probes have up to a 1.5dB difference between them across this frequency range.?

So something is obviously wrong with it and I think it will be the repair on probe B. It might be possible to improve things with internal compensation but probe B is obviously not right. The capacitance is too high for one thing. These diodes need to be replaced with something closer to the correct part.

I think the official HP 'tee' in the HP 11570A kit will be designed for a probe with 2.5pF input capacitance so it's obviously going to cause some issues if used with a probe that now has 4pF input capacitance. I don't have an 11570A kit here but I do plan to buy one at some point. I have a homebrew versions of the tee here but they are ugly lashups and I rarely use them. They are designed for a probe with 2.5pF capacitance though.

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What's your measurement setup, and what capacitance (and resistance) values are you seeing?

If you're seeing significantly higher capacitances, then I wonder about fixturing. Or maybe whoever did the repair wasn't careful about parasitics.

If you're seeing just somewhat higher C and lower R, then perhaps you could try some 1N5711s. These are often double-marked as 5711/6263, but the original 6263 had 10-15% or so higher capacitance, IIRC.

That is a fine instrument, for sure, and I hope you will get it back to like-new performance. It's also fun to use as a front-end for a 1GHz ETS sampling scope.

--Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
420 Via Palou Mall
Stanford University
Stanford, CA 94305-4070

The main problem is that the input capacitance of the probe is too high and the Rp is lower than it should be up at VHF when compared to a good probe. I think this could be caused by the wrong choice of diodes (1N6263). I won't know for sure until I'm able to take the diodes out of the probes. It's not my VVM yet so I can't do any further internal testing.

This VVM is in such good condition it deserves to be repaired properly and if I do buy it I will service/adjust it to try and get as close to the original performance as possible.
I've got lots of the HP accessories to go with these meters plus I made a few of my own plus I have various directional couplers to use with it.

It's all a bit nostalgic because I also have a couple of modern lab VNAs here, but the HP 8405A is a classic instrument and it's also quite educational to use. I usually use the DMM recorder outputs at the back for voltage and phase, but I might also experiment by coupling up an Analog Discovery 2 to the 20kHz outputs and code it up to measure voltage and phase at 20kHz.?

I have used these. 0.5mm CS is standard.

Those diodes should work fine, as long as they're matched (for both forward voltage and capacitance -- and be sure to tweak the adjustments for balance, as described in the manual). What problems are you seeing with them?

You'll want to replace them in matched quads for best performance. I once repaired a probe that had "never worked right", according to its most recent owner. It had been repaired before by someone who had replaced just one of the diodes. Replacing all four with 1N5711s (pretty much the same as 1N6263) that came from consecutive positions on a tape worked fine. If you can find some HSMS-280x surface-mount parts, they should work very well (these contain 1N6263-equivalent devices). There are even some in that series that are in the bridge configuration (though rare; I've never found them for a reasonable price).

--Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
420 Via Palou Mall
Stanford University
Stanford, CA 94305-4070

On 5/6/24 11:21, Jim Adney wrote:

Thanks for posting that Dave; I was not aware of that info. Is hparcive.com the site that people on this group are running? I tried to find out how you found the 400D-2C Service Note, but had no luck searching for it there. I was hoping to find more info, but there's no link to a "Service Notes" section, and even a general search for 400D came up empty. So how did you find this?
Or did you know it was there because you were the one who put it there?
I'd say that the directory on the home page could use a Service Notes entry.

If you're talking about HPWiki, no, hparchive.com is not that. There is a link for Service Notes on the front page of HPWiki, and 400D-2C is there.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

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Hparchive is run by Glenn Robb; I don’t remember him posting here.