Kalundborg radio

The Danish main broadcasting station at Kalundborg operates on 1150 metres, and is rated at an aerial power of 7.5 kW. It is of Western Electric design, incorporating a separate master oscillator and low-power choke modulation. The studio and line amplifiers are installed at Copenhagen, and the speech currents are taken over 60 miles of land line partly consisting of heavy-core type Krarup cable and the remainder open wire. At Kalundborg the line is equalised with perfect accuracy up to about 8000 cycles per sec. On further amplification the speech currents are passed to the transmitter. The antenna is of Danish design, and comprises four horizontal wires at a height of 100 metres with vertical current leads at each end at considerable distances from the masts. One lead terminates at the transmitter, while the other is connected to the earth system through a tuning inductance. When correctly tuned, each vertical lead carries the same current, and it is claimed that better distribution of the earth currents, and hence lower earth resistance, results from this scheme. Special attention was given to the radiation band-width for the transmitter. The description concludes with an outline of the safety devices and photographs of the apparatus.