Radio Beacon Converter

The radio beacon band extends from 280 kHz to 516 kHz. Each beacon has its own characteristic AM modulated morse-coded call sign that is transmitted on a specif- ic frequency. To be able to receive distant beacons, the aerial signal is passed through a band-pass filter that effectively suppresses long- wave and medium-wave signals. The filter also converts the aerial impedance, Zin, from about 10 1(0 to the inpout impedance of mixer ICI, which is about 1 ka The mixer adds or subtracts the received signal to/from the local oscillator signal, so that the beacon signal can be received on a normal short-wave receiver. The resulting frequencies lie in the range 9.72-9.484 MHz or 10.280-10.516 MHz. In the construction of the converter some components must be surrounded by a metal shield as indicated by dashed lines on the PCs layout. The circuit is aligned with the aid of an ssu receiver to which the output of the con- verter is connected. Tune the receiver to 10 MHz and adjust the osci...