Have you heard of an upconverting superhet?

 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.

Interestingly, sBitx is an upconverting superhet with IF at 40 MHz, much above the 455 kHz of single conversion superhets and higher frequencies of superhets with multiple levels of conversion. The advantage mentioned is that upconversion and use of higher IF eliminates the need for multiple filters, one for each band of operation. As HF operators are interested in frequencies below 30 MHz, when the local oscillator works above 40 MHz, image frequencies are well above 80 MHz. These can be easily filtered by simple low pass filter for the entire HF band. 25 kHz bandwidth crystal filter can be used with very sharp image rejection. Crystals with 40 MHz fundamental frequency are easily available at low cost. That looks like a novel concept. I do hope that this concept of upconverting superhet will revolutionize the HF radio segment. I have not been able to use sBitx. VU3SIO in this region has been having one for quite some time as he received one as the prize for a contest.