Comm noise

On Aug 29, 10:11*am, Orval Fairbairn
wrote:
In article
,





*John wrote:
On Aug 28, 4:55*pm, Orval Fairbairn
wrote:
In article
,

*John wrote:
I flew yesterday with an owner who pointed out that he is getting a
type of crackling noise over both comm radios. *The noise is most
prevalent when receiving from more distant and weaker transmitters
like other aircraft and not noticeabl when receiving from closer more
powerful transmitters i.e. the tower.

The owner has operated the aircraft with every other system turned off
including the alternators and has operated on individual magnetos with
no change. *The most recent change to equipment was an audion panel
installation. *The noise is not rythmic like ignition noise and does
not rise and fall with engine settings like some alternator noise. *It
is not as intense as the white noise when checking squelch. *It is a
type of random crackling like noise.

Any thoughts?

John Dupre'

I had a similar problem years ago, with one of those cheap whip
antennas. I switched to a high-quality antenna and got rid of the
problem.

It appears that moisture had somehow entered the material surrounding
the metal antenna and was causing arcing.

--
Remove _'s *from email address to talk to me.- Hide quoted text -

- Show quoted text -

I did notice that the upper antenna is loosing some of its coating and
the exposed areas look corroded. *I would replace the antenna for that
reason alone but the owner wants some more confirmation than looks.
The lower antenna (bent whip) doesn't appear corroded although the
whip portion is slightly bent.

John Dupre'

That would do it on the upper antenna -- especially if it has flown
through rain. Is the antenna airfoil-shaped or one of theose
wrapped-metal, round ones? I had the latter and it eventually succombed
to moisture.

--
Remove _'s *from email address to talk to me.- Hide quoted text -

- Show quoted text -

Wrapped metal round antenna with a tear shaped base.

In article
,
John wrote:

On Aug 29, 10:11*am, Orval Fairbairn
wrote:
In article
,





*John wrote:
On Aug 28, 4:55*pm, Orval Fairbairn
wrote:
In article
,

*John wrote:
I flew yesterday with an owner who pointed out that he is getting a
type of crackling noise over both comm radios. *The noise is most
prevalent when receiving from more distant and weaker transmitters
like other aircraft and not noticeabl when receiving from closer more
powerful transmitters i.e. the tower.

The owner has operated the aircraft with every other system turned off
including the alternators and has operated on individual magnetos with
no change. *The most recent change to equipment was an audion panel
installation. *The noise is not rythmic like ignition noise and does
not rise and fall with engine settings like some alternator noise. *It
is not as intense as the white noise when checking squelch. *It is a
type of random crackling like noise.

Any thoughts?

John Dupre'

I had a similar problem years ago, with one of those cheap whip
antennas. I switched to a high-quality antenna and got rid of the
problem.

It appears that moisture had somehow entered the material surrounding
the metal antenna and was causing arcing.

--
Remove _'s *from email address to talk to me.- Hide quoted text -

- Show quoted text -

I did notice that the upper antenna is loosing some of its coating and
the exposed areas look corroded. *I would replace the antenna for that
reason alone but the owner wants some more confirmation than looks.
The lower antenna (bent whip) doesn't appear corroded although the
whip portion is slightly bent.

John Dupre'

That would do it on the upper antenna -- especially if it has flown
through rain. Is the antenna airfoil-shaped or one of theose
wrapped-metal, round ones? I had the latter and it eventually succombed
to moisture.

--
Remove _'s *from email address to talk to me.- Hide quoted text -

- Show quoted text -

Wrapped metal round antenna with a tear shaped base.

Yup -- That's the kind that I replaced! Apparently, they last only so
long, then they get wet inside.

--
Remove _'s from email address to talk to me.