Triode RD250VM

Evaporation-cooled triode for frequencies up to 30 MHz, heater 17 V / 520 A, anode voltage max. 13 kV, 250 kW anode power, weight approx. 90 kg. These are the most powerful vacuum tubes ever produced by the Tesla company. Special ceramics is used instead of glass. Three of these tubes, connected in parallel, were used in the output stages of the SRV 750 medium-wave transmitter in Liblice and the DRV 750 long-wave transmitter in Topolná. The Topolná transmitter was switched off in 2014, the Liblice transmitter operated until the end of 2021. The Liblice and Topolná facilities used two of these transmitters running in parallel, so the output power was 1500 kW. To compare, a GSM mobile phone is equipped with a 2 W transmitter. Large TV transmitters usually have 100 kW nominal power. The 1500 kW power rating might suit an electric locomotive rather than radio equipment.