75S-3C with 32S-3 plus the KWM-2A with 75S-3

At top left is the very collectable 75S-3C receiver. It's paired off with a 32S-3 transmitter. They are coupled so they can transceiver or operate independently. This 75S-3C has a 3.1 KHz mechanical filter for wide band SSB. It is also equipped with a 500 Hz CW filter. Dial calibration is so accurate that it is competitive with modern solid state equipment. It's is not difficult to set a frequency to within 100 Hz. The notch filter is quite effective. There is one important and most overlooked difference between the 75S-3B and 75S-3C receivers with T-9 in their circuits and earlier receivers which didn't include that transformer. Receivers with T-9 have an extra, low gain i.f. stage of amplification. T-9 replaces a cathode follower in the Q-multiplier. The tube used for the Q-multiplier cathode follower is then available for use as an i.f. amplifier with T-9 working as the plate tuned circuit and step-down impedance transformer needed for the Q-multiplier. This is just one of the continual chain of receiver impairments in the S-Line.

On the bottom level are an unmodified KWM-2A and a 75S-3 which is coupled to the KWM-2 so that "dual receive" is possible. Both the KWM-2's receiver and the 75S-3 are operating simultaneously. The KWM-2 provides the necessary antenna and muting circuits. This is an excellent way to achieve "split" operation with a KWM-2. It's far less expensive than purchasing the matching 312B-5 external PTO which can fetch between $700 and $1000 on the market. However, this station features the 312B-5, too. So, there are several frequency setup options available.

Back