TT21 GEC CV8286 transmitting valves close equivalent KT88 GEC

Description

Both TT21 and TT22 by GEC are the same valves and they only differ for heater voltage.

The TT21 shown here are the 6 Volts heater version and are quite similar to a KT88.

The TT21 has top cap anode rest is similar to a KT88

Tested with AVO 163 at:

TT21 GEC tested 60mA

TT21 GEC tested 60mA

TT21 GEC tested 56mA

TT21 GECF tested 53mA