HP 3400A RMS Voltmeter thermocouple chopper Nuvistor 1965 teardown

this is a very cool Hewlett Packard RMS voltmeter, its fundamental design sounds quite simple, but its implementation is as always out of this world, released in 1964 and end in 1980 this one works really good, I managed to fine adjust it for best possible readout.
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#teardown
#hewlettpackard
#vintage
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I use auto generated subs, I go thru them my self, but i am far from perfect at finding all errors, so if you find errors worth fixing, please comment (or PM) with the TIME in the video you saw the error, i will be happy to fix it. This also apply to the Danish version.
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[lulrik]

That's an amazing device, now i want one <3 thanks for the review !

[jeanpierre]

The last version HP 3400C are a J-FET input transistor instead a Nuvistor (6CA7 maybe)

[chongli]

Love it! What a beautifully designed precision instrument! Would love to see it operating down in the lowest ranges! Looks like it goes down to 10 mV AC?

[Edisson.]

Hi Thomas, I'm back in civilization for a while, I've been watching videos in my spare time, but I haven't commented on them from my mobile.
I bought a 3400 on e-bay, unfortunately someone hurt it terribly, the input part is totally dead, the Nuvistor only heats up, but the signal does not pass, so I have something to do for the long winter evenings. When I bought it, I just wanted to do a quick commissioning and find out its condition, first I measured all the capacitors and after finding out that they were out, I bought a set of radial (they didn't have axial) 105° capacitors in a brick and mortar store for initial commissioning, with the provision that I would then order axial types. Before I started replacing them, I measured all the new capacitors to know what deviations they had from the prescribed value in the service documentation and I couldn't help but wonder - the old Sprague ones (the ones that were fine) had better parameters than the new ones bought in the store - reforming didn't help either. I'm quite jealous that yours works because it's an amazing RMS voltmeter. So far, I have put into operation the 209A oscillator and the 427A voltohmmeter from this series, for which I also made a new battery (it has been there for more than a year and it still works).

Nice day 🙂 Tom

[maxjakobsen]

Sådan en har jeg liggende, jeg har aldrig vidst hvad det var før jeg så din video.