Well, I had not heard of an upconverting superhet till I read about sBitx transceiver from VU2ESE. Usual superhets which I have heard of were downconverting superhets which downconvert the received frequency using a local oscillator and mixer to a lower frequency known as intermediate frequency or IF. There are single conversion, double conversion and triple conversion superhets depending on the level of sophistication of the superheterodyne receivers. Multiple conversions give better selectivity and image frequency rejection. Single conversion is often a compromise between selectivity and image frequency rejection, as discussed earlier.
