This permits choice of AGC characteristics to suit operating conditions. Coverage outside the amateur bands, or additional 10 meter- band frequency coverage, can be obtained by plugging in the appropriate crystals. The pitch for CW reception can be varied by turning the BFO control on and adjusting the knob for the most pleasing beat note, with the desired signal centered in the filter passband. When the BFO knob pointer is at the 0 reference mark, the BFO frequency is approximately the same as crystal BFO in USB position. With the knob in the off position, the crystal BFO is in operation.
RTTY operation requires a conventional converter and printer.
Also available is the 75S-3C, providing extended range coverage. It is identical to the 75S-3B except that an additional HF crystal board and front panel selector switch are included. The board for additional crystals is located on the top of the chassis and the standard group of amateur band crystals is mounted in the board on the underside of the chassis. Selectable single sideband, CW, RTTY and AM continuous. Power consumption is approximately 85 watts.