The Prague radio broadcasting station

The transmitter consists of six panels, three of which are assigned to the generation and control of the power supplies necessary for the radio transmitting circuits proper, which occupy the other three panels. A modulated carrier wave of 500 W is generated by five radiation-cooled tubes, amplified to 5 kW by two water-cooled tubes, and delivered to the antenna. For the first group of tubes rotating machinery supplies the filament and the d.c. plate supply, dry cells being used for the grid. For the water-cooled tubes d.c. machines supply the filament and grid, but the anode is supplied from a three-phase rectifier. The antenna consists of three down leads in the form of 6-wire cages and a flat top 40 metres long, supported on masts 40 metres high. The mean effective height is 20.7 metres, the radiation resistance being 5.07 ohms, and the antenna current 31 amperes.