... as always, under construction ...
On the "Main Unit" PCB:
Replace R154 (3.3M) with a 4.7M resistor. (This adjusts the squelch delay.)
Replace R153 (47k) with a jumper. (This adjusts squelch hysteresis. Increase the resistance for greater hysteresis.)
Replace R152 (10k) with a 2.2M resistor. (This adjusts squelch sensitivity and affects delay. Increase the resistance for more sensitivity.)
Replace C118 (0.022uF) with a 0.47uF polyester or other low-leakage non-polarized capacitor. (This adjusts the squelch delay.)
Replace D66 (1SS53) with a 1N34 or similar Germanium small signal diode. (This increases small-signal squelch sensitivity, the lower the Vf of the diode the better.)
NOTE: The values specified provide approximately a "two seconds plus the AGC” delay before the squelch closes.
That's all for now... 12-January-2001.