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CV2220

Sensibly equivalent to:
5B/257M VX7097
See also:
Beam Tetrodes and the 807 - STC 5B/254M, 5B/255M, 5B/257/M & 5B/258M Advert - STC 5B/254M, 5B/255M, 5B/257/M & 5B/258M Advert
    
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The CV2220 (commercially the 5B/257M) beam tetrode was designed for transmitter use in the HF and low VHF parts of the spectrum. The design has the same rating as the 807 but with a 12 Volt heater.
In addition to RF power, the valves were designated for service as audio power amplifiers. Here the valve was to operate in class AB1 and a pair would deliver 15 Watts at 3% total distortion.
The KB/F identifies this valve as being made to specification K1001 or K1006, the B denotes qualification by a UK authority and the F identifies the maker as STC, Paignton.
The beam tetrode construction seen at the top. Note the double mica discs to reduce the effects of long term exposure to vibration.
The wide glass tube envelope is 28 mm in diameter and, excluding the B8B base pins, is 76 mm tall.
References: data-sheet Type CV2220 was first introduced in 1952. See also 1952 adverts.

 

Pin Connections
B8B
1
2
3
4
5
6
7
8
h
a
g2
k,bp
g1
g1
k,bp
h

 

Absolute Maximum Operating Conditions
Beam Tetrode
Vh
Ah
Va
Vs
Vg
mAa
mAs
mAg
Pdriv
Pout
Pdiss
freq
12.0
0.47
600
250
-45
100
8
4
0.3W
40W
25W
60
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated January 07, 2026.
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