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Alternator Whine

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After a summer of being grounded due to radio problems my frustration has reached a high point. At the end of June I prepared to fly only to find my radio would not power up, everything else was fine but no radio.

 

After a couple of weeks I received it back from the factory and went to fly again, radio worked but had this static that sounded like what is referred to as alternator whine. It would increase or decrease with engine speed. Didn't get very far trying to trouble shoot because a week later it wouldn't power up. Back to the factory where they say it bench tested fine .

 

After wringing out the harness to prove to them it was okay they agreed to send me a loaner to see if it would power up, it did. Back to the factory again, in the mean time I tried flying with the loaner but it too had the alternator whine. Waited to get my unit back since I still didn't know if it was a radio problem or engine.

 

Finally received my unit back and whine is stil there, checked connections and replaced capacitor with much larger unit.No joy!!!! Only thing that works is to turn the radio off. Turning alternator off or intercom down has no effect.

 

For what it's worth this radio has never been a problem and reception has been excellent. It appears that the whine and not powering up happened at the same time although not necessarily connected.

 

Anyone had a similar experience or a clue of what I can do now. Missed all of the summer and maybe the

fall, by the time I get back in the air I hope I can still fly the bird.

 

Al Meyer

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I had a 2006 CTSW that I worked on that had alternator noise issues. The problem was ground loop feedback through the GPS. I found the problem by popping circuit breakers one at a time to find where the noise was coming from. A ground loop isolator solved the issue.

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You can fly out of your airport without a radio.

 

  I know this isn't about the radio.   But:  Many of us fly with zero radio.  It's good discipline.   If you're at a towered airport you should be able to arrange light guns out and back into your home airport.   Then you could at least fly.

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I'll try popping circuit breakers and see if I can isolate the source. Where can I get a ground loop isolator and how is it installed?

 

Another point I failed to mention was during communication , transmit or receive the noise is gone. I'm not a radio geek so don't know if that's significant or not.

 

We have four fields ( 1 towered and 3 non towered) in close proximity so I'm not comfortable flying without radio but if push comes to shove I can tolerate noise when close in and turn volume low when outside the active area.

 

Thanks for the imput

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I have had this whine for a while I hear it when I land and taxi back.  It turns off when I turn off my avionics master switch, not one of the two master switches but a switch that turns on multiple radios.

 

What I just realized is I'm not hearing over my headset, its loud enough to be loud over an idling or taxing engine.

 

If I switch it off with the AMS it goes away and doesn't come back (I'm sure it would come back if I took another flight)

 

What could this be?  

 

You can hear it pretty clearly in the last 6 seconds of this video, you might need your sound up.

 


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That's close to sound I get all the time except during communications. Mine is definitely engine generated since follows engine rpm.

 

Tom, thanks for the links, I'll check it out. If weather cooperates I'm going to try popping breakers tomorrow to see what effect that has. Im also getting suspicious of my intercom, my aux. input only works when the radio is off. It normally works all the time and only drops out during communications.

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