BRIEF DESCRIPTION 1. The H. F. Receiver Type RA. 222 is a fully transistorised unit that has been designed for operation in SSB and DSB radio systems with the Racal range of SSB transmitters and radio telephones. Receiver muting is available from connections at the rear of the receiver for when it is in close proximity to a transmitter. 2. Eight crystal controlled channels are available covering the frequency range of 1.5 to 24 Mc/s. All r.f. circuits are pre-tuned plug-in units and channel selection is by means of an eight position rotary switch. The eight channel crystals operate in a thermostatically controlled oven. 3. Switched selection is available for upper or lower sideband on SSB, and DSB or CW operation. 4. The audio output circuit feeds an internal speaker, an external loudspeaker terminal at the rear of the receiver, a headphone jack socket on the front panel and a line output at 600 ohms impedance. 5. The unit is of robust construction and suitable for bench or 19 inch rack mounting. VARIANTS 6. Alternative power supply models are produced for use on a.c. power, 12 volt and 24 volt d.c. supplies. In addition there are four versions available for operation from each of these power supplies with facilities as detailed below: - A. C. Powered RA. 222A SSB, AM and CW reception. RA. 222B SSB, AM and CW reception with squelch control fitted. RA. 222C SSB, AM and CW reception with extended control module MA. 34 6 fitted. RA. 222D SSB, AM and CW reception with squelch and extended control module MA. 346 fitted. 12 Volt d.c. Powered RA. 222G SSB, AM and CW reception. RA. 222H SSB, AM and CW reception with squelch control fitted. RA. 222J SSB, AM and CW reception with extended control j module MA. 346 fitted. RA. 222K SSB, AM and CW reception with squelch