[sdiy] [OT] Name that tube

[metasonix]

>The pressure isn't messured with the AC-gain.

It was...in the 1930s....

>First the triode type (and the other types like Bayard, Schulz etc.) aren't
>operated like a normal triode tube.
>The hot filament emitts electrons as usual. But the grid has a positive
>potential (120-200 VDC are common).

I know. The Bayard version uses the same connection, grid positive
and anode negative, measure the resulting grid current. 
It has the filament on the outside, something to do with reducing x-rays.

>I didn't have looked that up somewhere. I'm operating some of this tubes
>(bayard-alpert and a misused EC92) in my own high vacuum system with good
>results. And I definitely messure the pressure with the ion current from the
>outer collector electrode. Further the whole messuring circuit operates with
>stabilized DC voltages, so there aren't a dynamic resistance other any other
>dynamic properties involved in the messuring mechanism. ==> no variable AC
>gain.

Granted, but we're talking about an antique ion gauge.

What are you using this vacuum system for, may I ask?



uncle eric
metasonix.com