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Whining or Hissing Noise comming from Radio
- Thread starter T23
- Start date
I had a Cobra 2000GTL that did something simular. When Ide plug a power mic into it, it would have a high pitch whine on recieve and would get worse as you turned up the volume to where it was more like a squeal.
But if the stock mic was plugged in it wa sfine. I had did research on it and never figured it out so when I sold it I had to tell the guy about it. I never did find out if it was ever straightened out so a power mic could be used. Other than that is was a great talker and had great ears the radio looked brandnew.
But if the stock mic was plugged in it wa sfine. I had did research on it and never figured it out so when I sold it I had to tell the guy about it. I never did find out if it was ever straightened out so a power mic could be used. Other than that is was a great talker and had great ears the radio looked brandnew.
got same with my 2000. i turm down mic gain to 12 oclock and it
goes away.. then turn up power mic to desired level usually 1/2 half way
also. seems i get less background noise doing it this way also
goes away.. then turn up power mic to desired level usually 1/2 half way
also. seems i get less background noise doing it this way also
thought id chime in here about the squeal problem on the 148/2000 chassis, but i dont think its the same issue going on with the cybernet chassis.
with that one, i would guess that its the age of the radio and maybe some components going off value or going out completely that is the problem.
probably in the audio circuit near the chip.
as for the problem with the squeal on the 5 pin cobras, its usually a problem caused because some power mics dont do the switching the way cobra 5 pin radios want them to.
cobra had a different set up going on with the 5 pin radios as for how the audio shield acts.
take a look at the owners manual on cbtricks for the 148gtl for a diagram of what im talking about.
first, the mic should have 5 wires available on the cord.
the shield wire that is wrapped around the audio wire is connected directly to the negative lead of the mic element and is not switched.
this wire should always go to pin 2 on the mic plug.
the other ground wire is used for RX/TX switching, meaning it is connected to a terminal on the mic switch that is common to both RX and TX.
this would be the middle terminal on one side of the DPDT switches found in most mics.
the receive wire goes on one side so it is grounded during receive and the transmit wire goes to the other side so it is grounded in TX.
this ground wire gets connected to pin 4 of the mic plug.
the audio wire is connected to the middle terminal on the other side of the switch so that it is connected to the positive lead of the mic element in TX.
obviously, when power mics get involved, this can get complicated, and some will never accommodate this wiring scheme.
problems arise when the audio shield is connected to the negative lead of the mic element and is also grounded to the receive wire.
not sure how helpful this info is, but there it is. LOL
LC
with that one, i would guess that its the age of the radio and maybe some components going off value or going out completely that is the problem.
probably in the audio circuit near the chip.
as for the problem with the squeal on the 5 pin cobras, its usually a problem caused because some power mics dont do the switching the way cobra 5 pin radios want them to.
cobra had a different set up going on with the 5 pin radios as for how the audio shield acts.
take a look at the owners manual on cbtricks for the 148gtl for a diagram of what im talking about.
first, the mic should have 5 wires available on the cord.
the shield wire that is wrapped around the audio wire is connected directly to the negative lead of the mic element and is not switched.
this wire should always go to pin 2 on the mic plug.
the other ground wire is used for RX/TX switching, meaning it is connected to a terminal on the mic switch that is common to both RX and TX.
this would be the middle terminal on one side of the DPDT switches found in most mics.
the receive wire goes on one side so it is grounded during receive and the transmit wire goes to the other side so it is grounded in TX.
this ground wire gets connected to pin 4 of the mic plug.
the audio wire is connected to the middle terminal on the other side of the switch so that it is connected to the positive lead of the mic element in TX.
obviously, when power mics get involved, this can get complicated, and some will never accommodate this wiring scheme.
problems arise when the audio shield is connected to the negative lead of the mic element and is also grounded to the receive wire.
not sure how helpful this info is, but there it is. LOL
LC
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