1 . The RA. 1771 and RA. 1772 are fully synthesized solid state communications receivers providing reception facilities for LSB/USB (A3A, A3H, A3J), AM(A3) and CW(A1). ISB (A3B), FSK(F1) and AFC facilities are provided by optional, internally fitted, modules. In addition, a manual RF tuning unit may be fitted. 2. The built-in synthesizer is phase-locked to the output of a frequency standard, which may be either internal or external, and covers the frequency range 15kHz to 30MHz in switched 1MHz bands. In the RA.1771, the kHz setting is selected by rotary decade switches, with digital indication in 10Hz increments, while in the RA.1772 the synthesizer is continuously tunable over each 1MHz band and on electronic readout indicates the kHz setting to 10Hz. Except for the method of frequency selection both receivers are designed to the same specification.