....Impossibly to find a stand alone (and simple) squelch in the internet and in books that I have.
Had to cut and past from a bigger online receiver design and rework some changes.
Since last time I studied op-amps somewhere last century I forgot that ideal op-amps are not real ones, that's why there are so many models. The original design (first rework) was not working due the specific nature of "real" op-amps... the 741 didn't worked as expected.
It's a simple comparator circuit without hysteresis.... that is done by the lack of precision of the adjustable potentiometer movement (backslash et all), if it was a multiturn, probably hysteresis was a good thing to have.
There is space for improvement, for instance if the signal is to strong it will not block the audio (max signal value no enough), changing the 1k ohm resistor for a bigger value will allow that, in the other hand it is nice if your friend is calling you on frequency near your house....
And the video of it working (not a very explicit example since exactly when I was testing all the channels were with signals opening the squelch level I set):