The 454-H is a 250 watt triode with a mu of 27 made by Eimac. The HK454H was a tube made to compete with the Eimac 250TH with minor mu and plate current changes. This appears to be an Eimac tube made to be interchangeable with the HK454-H. The H&K characteristics are listed.
Length = 9.63" Diameter = 3.50"
Max voltage = 5000
Max current = 375 ma
Fil voltage = 5
Fil current = 10 amps GOTO INDEX