The 5642 is a directly-heated high-voltage rectifier tube. It has three flexible lead connections and is intended to be soldered into the circuit.
It is used in the CRT cathode and post-deflection acceleration supplies in many Tektronix scopes. In typical CRT circuits, the filament/cathode leads of each 5642 have their own secondary winding on the HV transformer.
|Heater||1.25 V, 200 mA|
|Peak inverse volrage||10 kV|
|Peak plate current||250 μA|