Repair Boonton sensor 51033 (6E)

[pe2ben]

Hello everyone,
Have someone experience in repairing the Boonton 51033 (6e) sensor (older version with black housing?
This sensor failed during zeroing.
Or does someone knows which diodes are used in this probes?
Thanks Ben

[edpalmer42]

Here's some info that I saved many years ago. 

https://web.archive.org/web/20061216013712/http://members.shaw.ca/novotill/MillivoltmeterRfProbe/index.htm

You're on your own for a translation of the French document. 

Ed

[pe2ben]

Thanks Ed,
Unfortunately this for the Boonton voltmeter ( 1.2 GHz) and not for the Boonton power meter (18GHz).
I can't find the french text.
But at the end from your link there are some information on diodes when i don't find the original ones.
Someone another  suggestion?
Regards Ben

[edpalmer42]

Thanks Ed,
Unfortunately this for the Boonton voltmeter ( 1.2 GHz) and not for the Boonton power meter (18GHz).
I can't find the french text.
But at the end from your link there are some information on diodes when i don't find the original ones.
Someone another  suggestion?
Regards Ben

Sorry Ben, I didn't look close enough at the page.  I guess there's more than one version.  Let's try again with a pdf.

The French text is in the document that's attached to my previous message.   

Ed

[Kosmic]

Some more info here. again in french. http://www.voilec.com/ham/boonton.php#repa

So the diodes appear to be paired and the copper foil on the diode has been manually placed to adjust the frequency response of the diode. Also, old probes can develop a lot of attenuation in low frequency but not in high frequency. This would be due to some oxidation in the probe and can be removed by carefully polishing the oxidized parts. The author of the web page was also looking for the correct replacement part for the diodes. he says they are better than BAT 1503.

If you need some paragraphs to be translated let me known.

[pe2ben]

Many thanks Ed and Kosmic,
Looks great !
It's a good start point.
Regards Ben

[1audio]

I'm undertaking something similar. However its a power sensor. I found the French note on repair but have determined that this guy is completely fried. The 2 100 Ohm resistors are open and the resistors in series with the diodes are open. The diodes are shorted.
I think I can replace these components but the construction has a cap that seems buried under solder on the input.
Does anyone have experiece rebuilding one of these? Modern parts are potentially much better but the actual optimization will be challenging at best. Is it worth the effort? (I got the sensor for $30.)

[1audio]

Here are some closeups of the internals of the sensor. There are 2 diodes and 4 "rod" resistors. All of them are fried. The diodes look a lot like HP 5082-2835's. I found some on e-bay. I have a good supply of 5082-2810 but my understanding is that they are less suited to this application. I found a source for the "rod" resistors- Smiths interconnect https://www.smithsinterconnect.com/contact/distributor-stock-check/  but the prices and availability is not going to work. I'm planning to substitute some RF 0604 resistors and hope for the best.