Hi all -
No, i don't think it's mic toob & I'm suddenly rich, but I couldn't find any
data on this toob. It's a sub-min tetrode (strapped as a triode in the
circuit), made by Victoreen, the date code implies that it was made in
mid-'62. Judging by the circuit (Geiger counter with the tube attached
right to the ionizing chamber), it's *got* to be a high-gain tube, and I'm
calling it a tetrode just 'cos it has 2 grids - perhaps the intent of the
second grid is ... ?
Does anyone know the tube, or where I could find some data?
Thanks in advance...
-dim

shiva wrote:

Hi all -
No, i don't think it's mic toob & I'm suddenly rich, but I couldn't find any
data on this toob. It's a sub-min tetrode (strapped as a triode in the
circuit), made by Victoreen, the date code implies that it was made in
mid-'62. Judging by the circuit (Geiger counter with the tube attached
right to the ionizing chamber), it's *got* to be a high-gain tube, and I'm
calling it a tetrode just 'cos it has 2 grids - perhaps the intent of the
second grid is ... ?
Does anyone know the tube, or where I could find some data?
Thanks in advance...
-dim

What you have is an 'electrometer' tube. It is used where a very high input
impedance is required, as in some measurement equipment. The gain is not
particularly high. The tube acts as an impedance convertor.

Grid one is run slightly +ve. The input potential is applied to grid two.
Victoreen made a lot of stuff like that, including precision very high
resistance resistors, ie, 1000 megohms, Etc. If you like I will post more info
on ABSE ref the tube.

John Stewart

"John Stewart" wrote in message
...
shiva wrote:

Hi all -
No, i don't think it's mic toob & I'm suddenly rich, but I couldn't find
any
data on this toob. It's a sub-min tetrode (strapped as a triode in the
circuit), made by Victoreen, the date code implies that it was made in
mid-'62. Judging by the circuit (Geiger counter with the tube attached
right to the ionizing chamber), it's *got* to be a high-gain tube, and
I'm
calling it a tetrode just 'cos it has 2 grids - perhaps the intent of
the
second grid is ... ?
Does anyone know the tube, or where I could find some data?
Thanks in advance...
-dim

What you have is an 'electrometer' tube. It is used where a very high
input
impedance is required, as in some measurement equipment. The gain is not
particularly high. The tube acts as an impedance convertor.

Grid one is run slightly +ve. The input potential is applied to grid two.
Victoreen made a lot of stuff like that, including precision very high
resistance resistors, ie, 1000 megohms, Etc. If you like I will post more
info
on ABSE ref the tube.

John Stewart


Hi John -
If you could, it would be great.
This thing's sitting in a kind -o sort - a Geiger counter - A Civil Defense
thingy from the late 50's (last cal date 69) a steel ionization chamber,
inside of a steel case, with the pickup hooked up right to the grids
(jumped) of the tube. I guess the kind
of a thing you kept in your "fallout shelter", waitin' for us pesky ruskys
to drop the big'un. I got the transistor oscillator going (it feeds of 1 C
cell), and the thing seems to be working now, though I have no way to test
the ionization chamber - Since it's basically a tin can inside of a yeller
metal case, I assume it only measures the "hard Stuff" (Gamma), and i can't
think of anything commonly available that produces enough gamma to make the
meter move. Thus far the only thing i've done was make the needle jump by
touching the grids. I have a '40's navy electronic tech book, and it
describes a bunch of radiation meters (down to photo paper...), but they all
have a sample for calibration - this one doesn't. Looks like a "homeowner"
model, with a CD stencil on the side - not a precision chunk 'o gear.
Anyhow, one of those "broken things to fix - but now what?" deals - thought
it might be a fun tube to play with... I've got an old grid leak meter I
never use, that's got some sub-mini toob in it too - though I guess I
should do something more productive, like comb out my black cat - of all the
cats, he's the biggest shedder... the keyboard is covered with cathair...
-dim