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CV73

Sensibly equivalent to:
11E3 KT44 Pen46
    
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The CV73 is a beam tetrode with aligned grids that is described for both audio use and television line output service. In the television role the valve can withstand a positive anode surge of 8,000 Volts.
Given its number in the Common Valve listings it is a good guess that this valve was designed in the late 1930s to coincide with the start of 405 line broadcast television in 1938. The CV specification sheet gives the function as a series modulator.
The anode is blackened to assist radiating away the heat generated. The ceramic insulators testify to the high voltages that appear on the anode in TV service.
The CV72 is essentially the same valve but with a 6.3 Volt heater and different connections.
The two grids are made of bright wire, probably molybdenum, and aligned one behind the other to minimise screen grid current.
The classic envelope is 51 mm in diameter and, excluding the B7 base pins, is 116 mm tall.
References: Data-sheet & 1040. Type CV73 was first introduced in 1938. See also 1938 adverts.

 

Pin Connections
B7
1
2
3
4
5
6
7
tc
nc
g1
s
h
h
k
g2
a

 

Absolute Maximum Operating Conditions
Beam Tetrode
Vh
Ah
Va
Vs
Vg
mAa
mAs
gm
Pout
D
4.0
2.5
250
250
-25
85
20
6.3
7.5
9%

 

Absolute Maximum Operating Conditions
Beam Tetrode
Vh
Ah
Va
Vs
mAa
4.0
2.0
-
300
21.5
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated January 04, 2022.
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