VK3YE, Peter Parker has churned out a mountain sized number of projects that are a three-fer. The Knobless Wonder is a great example where Peter has designed a 40M SSB transceiver that is a simple design, easy to build and works well (that's 3).
[Of note, if you are into DSB radios then VK3YE has the subject totally covered.]
In the 1st video where QSO's are being recorded VK3YE's has a terribly noisy environment as a routine challenge. The 2nd video was shot at the beach and thus you get a much better feel of how good this radio works.
Essentially Peter has a designed a 10 Transistor SSB transceiver whereby choosing the right crystals builds the Crystal Filter at the operating frequency (7.159MHz). So, no LO is needed, and the incoming signal is fed to the IF. Thus, no Knob needed for the main tuning dial ~ Knobless! Most of the supporting transistors are the BC458 (NPN) and the Driver and Final are BD139's.
VK3YE"s Knobless Wonder
A Build from JA2GQP
The BFO can be set above or below to give you LSB or USB. True it is a one channel radio but so is FT-8. The closest frequency that I could find for non-SMT crystals two years ago at Digi-Key was 7.200 MHz but are now obsolete. Surface mount 40M crystals can be found at Mouser. The 7.2 MHz ten-piece price is 21 cents. They also have 7.168 and 7.1505 MHz in surface mount stocked. I also see non-SMT crystals at Mouser for 7.175MHz. (Short can)
Could this be an opportunity to build a match box sized SSB transceiver to be featured on Hackaday (bragging rights). Forget Hackaday as the lurker detractors would complain it only operates on one frequency. The 20M Color Burst crystals are on 14.318 MHz and lots of POTA stations operate near there. So that is another opportunity.
About two years ago I did buy from Digi-Key the 7.2 MHz crystals and so that might be an interesting prototype project for this winter. The BFR106, a very rugged surface mount device, looks like a good fit for use on a project like this. This could be the answer to the Michigan Mighty Mite! My twizzle on this project would be to change the IF Module from 4 transistors to two and using micro relays steer the signals in one direction through the filter.
A HB to HB QRP QSO
TYGNYB
73's
Pete N6QW