The' SB-34 is a complete, self-contained SSB transceiver for operation on four amateur bands, 80-40-20-15 meters; requires only a microphone, antenna and primary source of power. This is advanced-design communications equipment using transistors throughout to replace vacuum tubes with the exception of those in RF Driver and Final Amp 1i f i er stages. Through extensive application of solid-state elements, (eliminating vacuum tube heaters) overall current drain is lowered, operation is cooler, life expectancy longer. Performance is equal to, in many cases better than equipment using vacuum tubes. Exceptional selectivity is provided by a mechanical filter. Bilateral amplifiers and mixers use common circuits both on transmit and receive and operate by controlling direction of amplification. In the SB-34 bilateral stages are used to process both the transmit and the received signal. By using this principle, we realize a saving in size and cost as well as eliminating circuit duplication.