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STC 5B/254M beam tetrode (CV428).

5B.254M size The valve measures 103x30mm overall and has a loctal base. The anode connection is the top cap.

See also CV2465 which is the fly lead variant of this valve made to a stricter specification

Heater voltage 6.3V
Heater current 900mA
Max anode voltage 600V
Max anode voltage (Ia=0) 750V
Max screen voltage 300V
Max anode current 120mA
Max anode dissipation 25W
Max screen dissipation 3W
Mutual conductance * 6mA/V
Inner amplification factor * 9
Max DC grid voltage -200V
Max RF voltage between g1 and g2 1000V
Max frequency for above ratings 60MHz
Cag 0.1pF
Cge 13pF
Cae 7pF

*: At Va=300, Vg2=250, Ia=72mA

Pin Function
1 Heater
2 Cathode and beam plates
3 Screen grid
4 Cathode and beam plates
5 Control grid
6 Control grid
7 Cathode and beam plates
8 Heater
TC Anode

Thanks to David Checkley for donating this valve

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