Squelch problem with GME 3400

Thanks Bucky
I have already emailed GME.
If I read the manual correctly I can set the overall squelch to minimum, moderate and maximum (may not be correct terminology) but it applies to all channels.
Cheers from the Moose

Thanks for that joc45.
It happens everywhere. Which would indicate that the vehicle is the source of the problem. 100 series V8 auto.
But if it was the vehicle itself producing the "signal" why is it that the problem will only manifest itself after picking up someone elses transmission? If there is no communication from outside then it remains silent. But immediately upon a transmission ceasing that damn noise persists.
Cheers from the Moose

Hi Moose,
The most probable source is the ECU, but there are a mulltidude of things which run microprocessors (a common source) these days, incl auto trans, electric aerials and windows. Even my dumb GU 4.2 diesel emits spurious signals which interfere with a mid-band VHF 2-way. The source often can be easily located, but stopping it is another thing (ask Disco and 100-series T-diesel owners). And I have a spurious signal from a nearby mobile base station near home.
The reason why you get the squelch staying open after a transmission is due to the hysteresis in the circuit; it will operate at one level of signal and drop out at a different level. The spurious signal is enough to keep the squelch open after a transmission, but not enough to open the squelch from zero signal.
Without getting too technical, it is possible for one particular design of receiver to pick up an unwanted signal, but another receiver will not. Sometimes the frequency of the unwanted signal is totally different to the receiver frequency, but design of the receiver dictates whether it rejects that unwanted signal or not.
Sorry I can't be of more help.
Gerry