The receiver design is straightforward. See picture.
Only the squelch circuit is special. The NE604 has a mute input. I made a comparator with discrete components. The comparator checks the level output with the squelch threshold. If the signal is below the threshold the mute is activated.
This receiver had been build a few years ago. It did work but I was not satisfied. It had no squelch, the demodulated signal was weak, it had no preamplifier. The mixer was a BF960. I improved all those issues. Now it works fine.
The preamplifier is a mosfet with a tuned circuit at the gate and one at the drain. It has an issue. When both the input filter as the output filter are peaked at maximum the preamplifier oscillates. So it t needs a small misalignment.
The input is shielded form the output but that does not solve the problem completely.
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