couple of issues with radio

Whining sounds like a ground problem.

 

The whinning is coming from the alternator. Ground is the issue. Check coax and bracket for antenna. If its corroded change it. If it looks ok run a ground wire from bracket to frame. Could be something simple like coax lose at either end. But if your modulation is low I'm going to bet its in the antenna or broken coax

 

OK grounding might help th whine. BUT have seen many cases where it wasn't enough. An inexpensive noise filter should help, if that's the case.

No audio:

Are yous using a power mike? Check battery or swiych to stock mic.
Is mic. good? Verify on another compatible set or borrow an identically wired mic.
Check wires in the mic connector, are they all connected and unbroken?
Open set and are all wires to mic. connector solidly connected.

If all the above appears OK... You might have a malfunctioning audio IC chip. Though this is least likely, as usually when these chips go, receive and transmigt audio are not present. But it is possible that the chip has malfunctioned.

 

what if the noise is coming through the antenna? grounding nor filters will "rectify" this issue.

the rectifier in the alternator is most likely the culprit and the only fix for that it to repair or exchange the alternator

 

Nope... Gunner 76 specified a whining noise. Antenna noise manifests as a "staticky" noise and can often be cured with one of those little balls that attach with a set screw to the tip of the antenna. Better yet Wilson and K40's are designed to eliminate this noise. Many other antennas now come with the little ball attached.

Now a true whine is surely alternator emitting some spurious harmonics/RF emissions. However the likelihood they are transmitting through the engine compartment to the radio is highly unlikely. It is more probable the power cord is acting like an antenna and transmitting noise through to the radio. I disagree on the diode. If that was the issue you would see a way high or way low reading on the gauge, or a rapidly fluctuating up and down movement corresponding to engine RPM's. Of course I am assuming that would have been mentioned. Also the am/fm radio in the car would be very noisy too if the diode were bad

Of course it's easy enough to check without replacing the alternator. Professional type battery/alternator testers include a separate function that indicates bad diodes. Places like AutoZone, Pep Boys or R&S Strauss will dun the test for free.... Of course if you have a regular mechanic he would most likely have a tester like this too.

 

Two quick things,

1 - the alternator needs a ground from the case to the engine and the engine to the chassis. This sometimes this causes issues. The diode pack is not the problem, if it was failing, then the alternator would also have issues. The issue you have with the turnsignals seems to confirm that it may be a alternator/chassis ground issue.

2 - if nothing else, get a dc noise line filter, put it into the power line (both negative and positive). Good ones are not cheap.

http://www.powerwerx.com/oem-connectors/dc-line-noise-filter-oem-t.html

 

You know... This is probably the best solution. IF you are getting out good and there are no other problems... This saves ALPOT of time. They do work. I have to admit if noise is the only problem, I have gone pretty quick to a noise filter solution in the past. You can spend way too much time trying to fix the problem and never find it. Some noise issues, from what I have seen, refuse to be solved.