Related design basis — KT8C was derived from the KT66, but uses a B5 base with top-cap anode instead of the KT66 Octal base with internal anode
Electrical Specifications
Absolute Maximum
Anode Voltage (max)Anode Voltage (max)600V
Screen Voltage (max)Screen Voltage (max)300V
Anode Dissipation (max)Anode Dissipation (max)25W
Typical Operating
Anode Voltage (typical)Anode Voltage (typical)600V
Notes
The KT8C is the ceramic-base variant of the KT8, intended for service in humid conditions and aircraft installations. CV1079 is the UK military designation assigned in 1941.
Top-cap anode connection — essential for the high-voltage insulation required in RF and transmitter service.
The r-type.org data lists operating parameters at maximum conditions (Va=600V, Vs=300V); typical AF operating points will be at lower voltages.
Described as 'a not very successful British attempt to emulate the American 807' — the longer electron path limits high-frequency performance compared to the 807 (65-100 MHz vs 125 MHz), though audio performance is considered excellent by some users.
Introduced in 1938. The KT8 family saw wartime RAF service as VT79 before being standardised as CV1079.