Help me troubleshoot gmrs alternator whine.

[Nigelcorn]

Hey all, I recently installed a Midland MXT275. It's working fine, but I've got a really annoying whine that varies with engine rpm.

I am currently running positive direct to battery, ground to the engine ground strap next to the battery. I tried to plug directly into the cigarette lighter to see if it would help, but no change.

I thought maybe having the antenna and the power cables routed through the same area running next to each other might have contributed, so I moved the antenna to the driver's side: no change.

I thought maybe the antenna (mounted on the front of the hood with an nmo mount might be the problem (lack of ground) so I'm I tried using the stock magnetic mount going back to the side of the bed where it's actually steel, but no change.

Lastly, I thought that maybe a wore from the nmo attaching screw to a ground would help, but it didn't make any difference.

What do you all think, anything I'm missing? I'm new to the gmrs world so I'm hoping it's something simple that I have overlooked.

Thanks.

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[Byrnesy]

I'd reckon a Amateur Radio guy could help. Possibly a ferrite coil on the power cable? But it would need the right turns, ie where the Amateur Radio operator could assist.

 

[Glad_he_ate]

That would be my suggestion add a filter to the power and even add one to the ground if need be.

 

[TwoSerious]

Have you tried disconnecting the antenna and seeing if the whine is still there? Could isolate if its your Ant picking up noise or if its noise coming of your power feed.

 

[Nigelcorn]

I haven't done that yet. I'll give it a try. I did switch the power direct to battery to try cigarette power and it didn't change anything.

 

[TwoSerious]

I would try first with the connector at the radio disconnected and then the antenna itself removed.

 

[Nigelcorn]

I guess I should have clarified a little bit, I tried to disconnect the antenna but what I neglected to mention is that I only hear the whine when the unit is receiving and the speaker is active. I don't hear any whine when it is on standby.

So, with the antenna unplugged there wasn't a whine, but that was only because I couldn't receive a signal.

I'll try and add some ferrite chokes to the power cables and see how it goes.

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