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Osram ET1 electrometer triode
| Filament voltage |
1V |
| Filament current |
0.1A |
| Mutual conductance Va=+4V;
Vg1=-2V |
0.05mA/A |
| Mutual conductance Va=+6V;
Vg1=-2V |
0.10mA/A |
| Capacitance: Cge |
2pF approx |
| Pin |
Function |
| 1 |
Anode |
| 2 |
Guard rings and screen |
| 3 |
Filament |
| 4 |
Filament |
| TC |
Grid |
This valve is designed to have
a very high input resistance so it can be used anywhere an electrometer
is required. The control grid is connected to a terminal at the end of
a special high resistance glass stem. The interal and external guard rings
and an electrostatic shield are connected to the base, and may be connected
to the negative side of the filament or given any desired negative potential.
To give the minimum possible electrical leakage the operating grid potential
should be greater than 2V negative with respect to the filament, the glass
should be perfectly clean and dry, and the valve should be operated in
the dark. In extreme cases it is also necessary to screen the valve and
input circuit, to use an anti-microphonic mounting, and to ensure the
filament supply does not fluctuate.
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