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1. 04:34 PM - Re: Re: Hum in Radio? (Doug McNutt)
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| Subject: | Re: Hum in Radio? |
At 17:13 -0700 9/3/11, Goodone wrote:
>I would say that the "hum" that I am hearing is about one octave below middle
C. It sounds a lot like the noise that you hear when folks are having trouble
with feedback with a microphone in a nightclub. I doubt very much that it is from
some noise source on the ground. Maybe it is being generated from something
in my aircraft that I do not hear while in the air. I also don't think that
it is from a bad connection in my antenna since I do not hear it at all on the
ground when I am on the grass strip that I operate from.
I have never played with an Icom IC-A24 but I suspect that it has an automatic
squelch scheme that is supposed to turn off received audio until there is a sufficiently
large signal coming in on the selected frequency.
If the squelch is set too low it's conceivable that it works properly at your home
base where there may be only a tiny bit of RF activity in the neighborhood.
On a large airport there may be a lot of transmitters such as ILS equipment
or radar that are "breaking squelch". That kind of noise would not usually
get described as hum. But ILS and VOR use low audio frequency modulation tones
that might come thru.
If your receiver has a squelch control you might need to adjust it differently.
If it doesn't there is probably an internal adjustment that could be mucked with
but somewhere it will say that needs to be done by a man with a radio license.
It isn't true though so long as you don't tune the transmitter.
Someone on this list probably knows about that particular radio.
OK on grass strip plus NG on a big taxiway seems to rule out something in your
aircraft power system.
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