Radio Buzzing

OK guys...I have a '65 Skylark with a Custom Autosound USA-1 (5) digital radio. I installed it last year, and it's always buzzed with the engine running, in any frequency. The buzzing increases with engine RPM. Here's what I tried...cleaned all grounds, no change. Connected the memory wire to the fuse box at the cigarette lighter...no change (it was at the cigarette lighter). Changed the coil and put new capacitors on the coil and voltage regulator...no change. Unplugged the alternator, no change. Put a noise filter in line with the main power wire, no change. Still buzzes...only with the motor running. Any ideas??? I'd sure appreciate them... Thanks!

Aaron

 

Popping increasing with rpms as opposed to whining? I suggest you consider changing the spark plug wires to a resistor --meaning a shiieded type.

 

Only occasional popping--it's a definite whining noise as engine speed increases. It's like a crackly whine. The plug wires are 8mm radio suppression wires...

 

That would suggest a need for a notch filter on the alternator.

 

Your 65 came with a #1959455 filter capacitor if it was not a 62amp alternator.

If it was a 62 amp it was a #1961891.


If that does fix it then a diode is deteriorating in the rectifier bridge in the alternator. Try another alternator and see if the noise goes away.

 

Any idea on where to find those filters???

 

You can get ground loop isolators from radio shack.
Along with 12v+ noise filters.

 

unplug the antenna cable and see if the problem goes away ...
if it does ... then an antenna filter might be the trick.

 

The whine caused by what is commonly caled a " leaking" diode in the alternator can be bad enough that even a filter cannot eliminate it.

 

I will try all those...Thanks for the advice...Jim, the alternator looks like it's been rebuilt ( I bought the car 2 years ago)...if all else fails I'll take it off and get the diodes tested at the shop...