▼ Menu

42OT

Sensibly equivalent to:
CV2511
See also:
Cossor Output Tetrodes Advert
    
Extras ▼

 

The 42OT is a tetrode audio output valve that dates from 1937. This exhibit has lost its type identification but retains the etched makers name.
Having measured the heater at 2.0 Amps at 4.0 Volts I looked through all of the B7 based Cossor valves and the 42OT came out as the type. The advert confirmed the identification.
The anode load is given as 8 kΩ, the cathode resistor as 140 Ω and the output power as 3.1 Watts.
The base connections indicate a g3 or beam plate but Cossor describe the valve as a tetrode. The advert shows a pair of vertical rods in the plane of the grids but outside them. The image of the pinch shows a connection from the left rod to the base and so this is probably designed to reduce secondary emission from altering the characteristic curve.
The Cossor name and country of origin are clear. The BVA logo is at the top and the V8 is probably the date code.
The control grid is wound on copper support rods.
The classic envelope is 56 mm in diameter, and excluding the B7 base pins is 114 mm tall.
References: 1043. Type 42OT was first introduced in 1937.

 

Pin Connections
B7
1
2
3
4
5
6
7
1
g1
g2
h
h
k,g3
a

 

Absolute Maximum Operating Conditions
Beam Tetrode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
4.0
2.0
250
250
-5.5
34.0
6.0
-
7.0
Updated December14, 2012.
Return to Main Index