The 4X250B is a 250 watt, forced air cooled, power tetrode with a full rating frequency of 500 MHz. The same tube with a 26.5 volt filament is the 4X250F. These tubes were some of the first ceramic of this type and their designation soon changed to the 4CX250B to separate them from the glass tubes. Early versions have engraved markings as shown in the second example.

Length = 2.47" Diameter = 1.64"
Max voltage = 2000
Max current = 250 ma
Fil voltage = 6
Fil current = 2.6 amps         GOTO INDEX