The HY51B is a 65 watt triode with a mu of 25 and full ratings to 60 MHz made by Hytron. The HY51A is the same tube with a 7.5 volt, 3.5 amp filament. The original tube (1938) had a white ceramic base and later tubes had brown baklite bases and an added ceramic insulator for the plate cap.
Length = 6.50" Diameter = 2.25"
Max voltage = 1000
Max current = 175 ma
Fil voltage = 7.5
Fil current = 2.25 amps GOTO INDEX