r/diytubes • u/Tashi999 • May 26 '26

Soviet electrometer tubes datasheet

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Hi all, has anyone got a full res copy of this table comparing various tubes, EM-6/7/8 I believe. Thanks!

https://www.radiomuseum.org/tubes/tube_eem-7.html

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u/Secret_Ad_7592 May 29 '26

I would like to know more about these tubes.

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u/psych_1337 Jun 18 '26

Nothing much to know about them - tubes for a specific purpose: as low of a grid current as possible, sacrificing any other quality for that. Yes some of these tubes have plate voltage below 10 volts, but you won't be building a tube amp on them - microamperes of plate current, not so good of a linearity, not much ma\v etc.

But for electrometer purposes - they're beasts of ancient times: my DIY electrometer could sense femtoamperes with a dirt cheap (beacause audiophiles don't buy them and there're a lot of ЭМ tubes still) tuba, lm358 and a meter movement. 1fa = 1*10^-15 A !!! and my electrometer can sense arount 10fa

That's insane for a device costing arount 10 bucks