Reflex circuits originated in the valve era when valves were expensive. Reflex circuits allowed valves to be used as RF and AF amplifiers. The same idea can be used on transistor circuits. Although I have not tried it, this maybe a way of making a 10m AM RX with a narrower bandwidth than a super-regen? Sensitivity should be good.
I have the honour of me being asked by Clive Sinclair for advice!! Yes, he asked me for advice! This was in the 1970s when he was after an antenna for his pocket TV. I can remember this like yesterday. Quite an honour.
Peter has kindly given me permission to use his images.