 The output of these PAs used a series-combining scheme to feed the RF power into a 100 ohm co-ax line.This fed the main mast, the other two being parasitic and providing the directional element necessary as the purpose was to get the maximum signal eastwards into Europe.The GL898 valves were water/air cooled triodes utilising a three-phase heater supply and having an anode dissipation of 40 kW.