The CV79 is a split anode magnetron designed to produce 200 mW at 4.547 GHz.
The CV79 and CV89 (frequency variant of CV79) were used in Wireless Set No.10 Mk.I, which played an important part in the WWII D-Day landings. This was a trailer mounted installation, using pulse modulation to enable 8-channels (eg 8 phone lines) over a 50 mile (optical) path. The associated receiver made use of the CV90. The Mk.II version used two CV228 heil tubes in the transmitter instead of the CV79 or CV89. (data courtesy of Jeremy Harmer).
The Z by the up arrow identifies the maker as MO Valve Company, Hammersmith.
The CV79 and CV89 were both based on M-OV experimental valves.
The split anode with the cathode passing centrally through the anode strips.
