Radio Power Problem

Possible broken antenna cable, or disconnected antenna cable.

 

It sounds (or not <pun intended>) like you've lost the antenna connection. Sometimes when I'm relocating my stuff into a different truck, I'll forget to turn off the radio. When I plug in the power wire, prior to connecting the antenna, everything lights up, but, all I get is dead air. When I screw the coax into the back of the radio, the racket come to life.

 

Well, if you have checked SWR's, then that eliminates a break in the antenna cable somewhere.

Anything else would be a pure guess, so I can't help any further. I have seen bad mic's cause this.

 

A blown final will cause this.

 

I would try another mike for your radio. I don't think it's the antenna. If there is a broken wire in your mike cord it will do what you're experiencing.

 

You never mentioned what brand or model of radio you have.

Most of todays radios will allow the receiver to operate but the speaker won't be active without the mic. You should still see receive indications on your S meter even though the speaker doesn't make a sound w/o the mic.

A few older radios required the mic plugged in before the receiver was given power to operate. I doubt you have a radio like that but one never knows.

The issue is that your transmitter isn't coming on as well as no receive indication on the meter.

The one thing that can cause both the receiver & the transmitter to fail simultaneously is the PLL (phase locked loop) section of the radio.

This is the circuit that receives its instructions from the channel selector & converts that info into the channel to listen & talk on.

If this is the culprit, it shouldn't be too expensive to repair unless the parts are obsolete. It might even be that someone mistuned the pll adjustment coil to where it was on the edge of working/not working at a certain temperature. It can be that critical on the very edge of operation. The fix, of course, is to readjust it to the proper setting.

Another common failure in the pll section is the crystal used in the reference oscillator section. It can be damaged thru age &/or sudden sharp vibration (like dropping or banging the radio). These crystals are easily scrounged from a parts radio or new from the parts suppliers. Last I recall, the cost new was maybe 5-10 bucks.

One more item of common failure is the voltage regulator IC or diode that keeps the voltage to the pll very steady. If these fail, the pll either gets no voltage or not enough to run on. The IC's might run 5-10 bucks, the diode typically runs under a dollar.

These prices don't include the installation & actual service time to see what's wrong.

Lastly, there's a handfull of little things that might be wrong. A bad solder connection, cracked printed circuit board, a shorted capacitor etc etc.

Except for the cracked pcb, none of these are hard to fix.

Hope this helped some.

As a PS, make sure the radio isn't in the PA mode or weather mode.