This is half of the Yaesu '400 twins. All-tube curcuitry from the early 70's. The FR-DX-400 Receiver has ssb, cw, am, fm, reception on amateur bands in the freq. range from 1.6 mc. to 148mc. The receiver provides several opertations, such as rejection tuning, slow/fast avc time constants, squelch circuit, monitor circuit and a 100 kc /25kc calibration. The receiver can be used as a tranceiver when used with FL-DX-SSB transmitter. covers hf bands from 1.7 to 30.1 mc.and 9.9 to 10.5 mc.It also has the optional fm detector unit and 2 meter and 6 meter convertor boards