Tesla ZD1000 transmitter tetrode

A transmitter tetrode for up to 60 MHz, with 1 kW anode dissipation, max. 4 kV anode voltage, 7,5 V / 34 A heater, radiation cooling - the anode gets red hot during operation. It is still used in transmitters, high-frequency heaters etc., it is still manufactured by the Tesla Electron Tubes Company in Říčany near Prague.