PTBM125/131 Soft squelch mod?

[163TM847]

These boards don't usually need a soft squelch mod so I have never looked into it before, But I have a PTBM131 here with quite a thumpy squelch, Does anyone know if there is a soft squelch mod for the 125 and above? I don't seem to be able to find any info anywhere, Only for 121 and 059

Cheers.

[lbcomms]

We've been asked lots of times to do that mod to Cybernet base radios to get rid of the thump sound. Basically isolate the collector of the last squelch switching transistor from the rest of its trace, then link the collector side of the cut to the post that feeds the volume control (the outer terminal that's not ground, not the centre "wiper").

This is for the PTBM125A:



Doesn't completely mute the radio in some cases, more like a 99% reduction, but most owners prefer that to the clunking.

[163TM847]

After removing the top lid I could see why the squelch was thumping louder than usual, At the factory, the collector of Q28 was already cut and linked [as seen in the top photo], I removed the link and reconnected the collector, and squelch returned to normal, Why the factory chose to "make it worse" is a little confusing, Anyway, I disconnected the collector again and ran a wire to the pole to the hot side of the volume as you suggested [Hotside [Blue] can be found on P8 right at the very back middle of the PCB] and squelch is now much softer.

Thanks

DSC03660.JPG

PTBM131 SQUELCH MOD.JPG

We've been asked lots of times to do that mod to Cybernet base radios to get rid of the thump sound. Basically isolate the collector of the last squelch switching transistor from the rest of its trace, then link the collector side of the cut to the post that feeds the volume control (the outer terminal that's not ground, not the centre "wiper").

This is for the PTBM125A:



Doesn't completely mute the radio in some cases, more like a 99% reduction, but most owners prefer that to the clunking.