[Jon_G4MDC]

That IC1 in the original active filter circuit is still being tricky.

The 3046 transistor array doesn't seem to work for it.
The 3096 is a different transistor array but it has 16 pins so that is ruled out.
LM324 quad OpAmp was around from 1972 but it doesn't match.
uA757 was in use then for IF Amps. I don't think they repurposed that.

I found these arrays of transistors which I had not seen before but I think they are quite recent devices. So far I can't see how they might suit.

Still stumped so far. Ticker-om as they say in Sweden.