Hello. Im about 1/2 way through building the simple superhet rx in
doug demaws qrp notebook. (The brown covered one).
It uses a ca3028 mixer ic followed by a crystal filter and 1350 if
amps. Far Circuits sells a circuit board (which i purchased).
the main board is compact..about 4 inches by 3 inches.
Covers just one band..but you can use external converters to cover
other bands.
Let me know ..i could send you some info..jpg files i could scan.
Another good rcvr is the one in the ARRL handbooks ..it uses dual gate
mosfets ..I think its in the early 1990s handbooks.
73 Earl VE3AB