I think I've killed my CB Radio

[Spider255]

Hi... today I decided to get out one of my old CB radios. I loved this old radio, its an AM mid band CB from the 80s and I had it setup with America coming in really loud and clear, I was blown away by how clear they were coming through and I had no mic for the radio, All's I had was a mic lead with no mic on the end so I searched my junk box for a mic to connect to it. After connecting the mic I keyed up and I got a loud squeal so the mic wasn't wired correctly but I noticed I was no longer receiving any signals, just white noise.

Have I just fried the receiver in my CB radio?

Is it possible to fry a receiver in a CB radio by plugging in a mic that wasn't wired correctly?

 

[slowmover]

I can’t say, with any certainty, it was the cause. Right to be suspicious, granted.

Posted to say that, if so, it’s something maybe all of us have done. (Made a mistake).

 

[prcguy]

I have never seen mic wiring that would damage a receiver. About the worst you can do is short out a 5v, 8v or 12v line to feed something in the mic but those should be current limited and protected.

 

[Spider255]

Thanks... I don't really understand how everything inside is connected together or whether I spewed RF into the receiver stage and ruined something. I'm only running 4 watts and SWR is 1.1

I'm based in the UK and I've never heard America come in that strong before, I was listening for hours in amazement and I began to get very eager to make contact... after messing about trying to get a mic to work with it, after I keyed up and got that high pitched whine noise, the receiver went dead just white noise.

Conditions normally fad slowly they don't just cut off like that but I'm just hoping it was conditions dropping off and that I haven't fried the receiver. I'm not sure if anything is connected from the mic socket to the receiver in some way where I could have shorted voltage from the mic wires into the receiver somehow or even put RF into something from the mic wires. My understanding was that it was two wires for switch that go to the PTT button on the mic and then ground and audio wires to the mic piece.

I didn't think to measure any voltage on the mic wires before I started messing about with it, I just tested for continuity to get an idea of what goes where.

 

[spongella]

An old CB radio I once owned required the microphone to be plugged to activate the audio section. Kinda' weird but that's how it worked. Perhaps this might be somewhat related to your problem.

 

[Spider255]

I think all CB radios have that issue, its just a case of shorting a pin to ground to get sound.

The radio came back to life today so the receive is still working, America was booming into London UK again. It must have just been conditions yesterday where signals vanished making me think I had blown something on the receiver.

I did open up the radio and there is a wire on the back of the circuit board that has become disconnected and I have no idea what that was connected to but doesn't seem to have any affect on the receive side of things but could explain why I've been having such a hard time trying to get a microphone working with this radio.

 

[N1EXA]

I think all CB radios have that issue, its just a case of shorting a pin to ground to get sound.

The radio came back to life today so the receive is still working, America was booming into London UK again. It must have just been conditions yesterday where signals vanished making me think I had blown something on the receiver.

I did open up the radio and there is a wire on the back of the circuit board that has become disconnected and I have no idea what that was connected to but doesn't seem to have any affect on the receive side of things but could explain why I've been having such a hard time trying to get a microphone working with this radio.

Make and Model number would help us !
Here is a help link for you.
Pete N1EXA

Microphone Wiring Diagrams - www.WalcottRadio.com

www.walcottradio.com

 

[Spider255]

Make and Model number would help us !
Here is a help link for you.
Pete N1EXA

Microphone Wiring Diagrams - www.WalcottRadio.com

www.walcottradio.com

Its an old Maxcom 4E and the mic socket is one of those DIN types.

 

[N1EXA]

Its an old Maxcom 4E and the mic socket is one of those DIN types.

Dont know the actual pinout But the chart should help you out.
You may have to break out the soldering iron in Jewelers screw drivers and do some Moving
of the wires.

Pete N1EXA