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GEC CV451 / ET3 electrometer triode

Size This valve measures 47x10mm overall and has a 3 lead base.


Filament voltage 1.25V
Filament current 25mA
Max anode voltage 9V
Mutual conductance * 70µA/V
Amplification factor * 1.0
Min grid-cathode resistance ** 1014 Ohms
Cg - all 1.7pF
Cga 0.2pF

*: At Va=6, Vg=-2.

**: At Va=6, Vg=-3.5

Connections: Anode is the centre lead in the base, and grid the lead at the other end. Filament +ve is the lead not in line with the grid lead, filament -ve and the internal shield is the other lead.

The valve is designed to be operated in darkness in a dry container made of metal to serve as an electrostatic shield.

Paper work with the valve:

Valve type RT3

Important notice

Don't touch the glasswork

The bulb of this valve is specially treated, and must in no circumstances be touched by hand.

When required for use, a quarter of an inch of paper should be carefully torn from each end of the paper envelope, exposing the tinned leads.

Which the calce [sic.] still in its envelope these leads should be soldered to the appropriate points in the circuit, using only "Ersin" of resin-cored solder. No other form of flux must be employed.

When the leads have been soldered in position the remaining portion of the paper envelope should be carefully cut away taking great care not to finger the glass bulb.

Note - Please keep this leaflet for future reference, and when re-ordering ask for Osram valve Type "ET3".

Ref. e.1959 - VX.3094.


This file was last modified 15:28:46, Tuesday September 02, 2014