Postage £4.45 first class
Give your transmit signal a boost –
The Datong RFC takes in microphone level audio; makes SSB at around 60 kHz with it; clips and demodulates the SSB envelope back to audio; filters it and sends it out as audio. The reason it goes to all this trouble is to maximise the effectiveness of the clipping (make the signal sound as loud as possible) as observed at the remote receiver, consistent with minimising distortion on the transmitted signal. Units that operate purely at audio frequencies cannot clip as aggressively (and thereby achieve the same level of perceived loudness improvement) as, in trying, they would distort the signal too much.