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
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On 5/6/2024 6:24 AM, jmr via groups.io wrote:
Hi
I know this question has been asked numerous times on the internet and it has been discussed here before, but does anyone know the part number for the Schottky diodes in the HP 8405A sampling probes?
I'm aware of the Richard Carey W6RLC pdf document that suggest using 1N6263 diodes but looking at the datasheet, I think the 1N6263 is not going to be the same as the original diodes. I really want to restore this VVM to full working order and it has some issues with the probes.
