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Agreed. That would be extremely useful. The -40V rail's operating spec max is 0.5A - so I can increase the current dummy load I have in place by quite a way yet - I'll try that next. thanks Tony

I did a simulation of the clamp and it clamps at 5v, both polarities which is under the 6v reverse breakdown so the thing shouldn't get zenered. It's a bit tight though! As for the JFET pricing, it's

FWIW, Mouser have over 8000 PN4117A. at $3.17 each. I don't know how easy/expensive to get them to ship in the UK though. You don't need the metal can version - HP switched to plastic packages for

Orin Eman: The B-E diode is zenered by back reversing it. It increases 100s times or more increases the B-E diode leakage if zenered once. There is a need for back to back 2N3904 B-E diodes to avoid

The 1901-0586 is also used in the 34702A, in which it is listed as "DIODE: SI 30 WV 10PA LEAKAGE", so I would say that a low-leakage JFET would be a perfect choice as a replacement. A 2N4117 or its

Yes, a 2N3904 B-E is next best after the FETs for leakage, but doesn't have a very good reverse breakdown spec - only 6V.

Has anyone used canned air (R134a, er=1.0113, plus a bittering agent) to backfill sealed HP modules? I don't have any dry nitrogen on hand, canned air doesn't seem to kill the performance, and it

As to my knowledge option 005 was never covered by the regular service manual , back in my tucker days I remember seeing a addendum that was published to be added to the service guide that covered the

There is separate protection for the AC, ohms and current ranges from what I can see. I haven't traced the whole thing out here or checked the whole DMM out yet, only the DC path.

Chris Smith: Good to know. I will look at the schematic later this evening to see what they have done. Strange to clamp later on leaving the input buffer amp and AC converter open to burn out. But

Low capacitance is not an issue as it's after the AC converter so low voltage slew. It can be considered a DC amplifier with very low bandwidth at that point. There is actually 0.1uF to ground anyway

Chris Smith: What about capacitive loading at the clamp point ? Looking at the service manual for 5 minutes I see no spec for the accuracy when fed 100 kHz compared to 50/60 Hz. I am thinking that it

Hi all, I'm looking to get my hands on a copy of the HP/Keysight VEE Pro software development package for tinkering around, but I'm not able to fork out the full cost of the current version for my

Dave , Incorrect, the 46GHz used a 2.4mm , it was a connector that is similar to the ones used on VNA (NMD type) , google pictures of the 52B with option 05 and you see the difference

Thanks all for the replies. I looked into this as well and came across similar FETs. The only problem is obtaining them cost more than I paid for the meter. It turns out the B-E junction of a 2n3904

Oops, I meant 2n4416.

Hi Tony I am surprised that the power supply even starts with such light loads.? I know that Askild has a 8623A which uses Meanwell units, perhaps he would be so kind as to measure the actual

Great! Let us know how you get on. Ohhhh yes. :-) -Dave -- Dave McGuire, AK4HZ New Kensington, PA

I found some adapters on eBay and they're on their way. Thanks for the responses. Interesting rabbit hole I seem to have fallen into!

Hi G :-) I attach a picture of my PSU dummy load.? This should translate to the following: +23V? ?9.4k? ?2.4mA +5.2V? 15R? ?346mA -10V? ?56R? ? ?178mA +20? ? ?390R? ? 51mA -40? ?