[sdiy] CA3028

[mirwin at qouest.net]

David,
CA3028 is/was a mainstay ham-radio chip for a long time.. it dates back 
to around 1969. Ham flea markets/old ham gear/old radios could be good 
places to check.

The circuit could be built using 3 of the transistors in a CA3018 
or CA3046 or similar chip. Might even be possible to use a uA703/LM703 
IF chip.

It may not be too exciting, though, as the schematic shown relies on a 
fixed LC resonant tank circuit to extract the desired harmonic from an 
overdriven diff pair... it expects a particular input frequency.  Same 
thing (and more) could be obtained with a fuzzbox and a multimode 
filter.
Regards,  Mike