Some years ago a beautifully simple circuit for a 40m CW transceiver by W2UW was published in GQRP SPRAT. This inspired me to have a go at an even simpler version for 80m using just 14 parts apart from the key and crystal earpiece. You would be hard pressed to get the parts count lower and achieve solid and reliable local (and DX?) communications. Basically the circuit shares a single MPF102 FET between a very simple regenerative RX and a QRP crystal oscillator. RX and TX switching consists of a 4 pole 2 way switch which changes over the antenna and all 3 connections to the shared FET. If you want a simpler TX-RX switch you could use two FETs instead. Although a little PCB would be neater, I just used ugly construction on a piece of single sided copper clad board. The FET is mounted on the back of the switch. The small aluminium box was obtained from Maplins.
NOTE: Please note that this simple receiver will radiate a small carrier on the frequency to which it is tuned (because it is set to be just in oscillation), so avoid using this when operating in close physical proximity to other 80m CW stations.
What amazes me is how well this little circuit works: the RX is stable enough and not at all fiddly. It is, all things considered, remarkably sensitive and picks up plenty of European SSB and CW signals at night. On transmit, the signal reports have been good. Even buying all parts new it will not cost you much more than a fish and chip supper. For me, this sort of circuit is the ultimate QRP challenge. Making and using it has been real fun. Next I want to try the same idea on 28MHz. Check my website and blog pages for latest developments and news of further contacts.