Noise feedback

[DSmith3]

I have a strange noise feedback. I have installed a Ham radio, Mobile Scanner, CB, and power speaker. My power lines consist of two separate feeds directly from the battery. One pair of the power lines leads to a Rig runner power strip. The other leads directly to my Ham radio.

When I tune a local police frequency to my Ham radio, and also my scanner I receive strong engine noise. To the point that I get the whining sound in conjunction with my accelerator. In other words acclereating or decelerating sounds come through.

This only seems to happen with this one frequency. 155.115

Keep in mind that the scanner, and the Ham come from two different power lines. The Ham is direct from the battery, and the Scanner from the rigrunner power strip.

Any ideas on how this is happening, and how to make it stop?

 

[MMIC]

I find it odd that alternator whine gets in only when you are on a certain frequency. Is the negative lead connected to the battery? If so, try using a different (but common) ground point for the two radios, such as the engine block or a well grounded point at the body, and see how that works. If not, you may want to try some filtering on the power connections to get the alternator noise out.

I'm sure others will have suggestions, too This topic always brings in the people!

 

[DSmith3]

Looks as if the problem is now getting worse. It works on any frequency now, and where as it was only intermittent before, it now is becoming increasingly more steady. (and annoying)

 

[LarrySC]

They make in line filters for that. Check local CB shop. Also they use to make a tuneable coil for same thing.

 

[SLWilson]

Ground

Shorten your ground wire. Find a ground and connect the radios with a wire AS SHORT AS POSSIBLE and try that. I had the same situation in a 1988 Chevrolet full size Blazer. Tried EVERYTHING including filters. Nothing worked until I grounded everything to the seat bolt right at the radios!!!! Steve/Gallia

 

[DSmith3]

Antenna problem apparently. Now if I disconnect the antenna the noise goes away. Suggestions on how to get rid of this??

 

[69Mopar]

Antenna problem apparently. Now if I disconnect the antenna the noise goes away. Suggestions on how to get rid of this??

Some cars are just noise prone. Try moving the rig to another car and see if the noise stops. If not, then it may be a bad ground on the antenna coax. If the noise goes away, then it's time to go the noise supression route. Ground everything including the muffler, trunk, hood, etc. Hope this helps.

 

[SLWilson]

Ground it

Antenna problem apparently. Now if I disconnect the antenna the noise goes away. Suggestions on how to get rid of this??

I had a similar problem (Chevy again) and ran a ground wire from the antenna connection at the back of the scanner directly to ground and cured it. Steve/KB8FAR