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Re: Mode S AO51



Hi Art,

In my experience, there are periodic very short fades on 51 that are going to be tough to overcome. Not a deal breaker on voice, as long as you wait them out for a few seconds. I experience them portable with the dipole/corner reflector, or on the 3ft dish, helix/preamp feed.

Another thing I have discovered is that even the circular patches and helixes exhibit some degree of linearity to them. That sort of thing is tough to tell mounted on a dish, but holding it by hand it's easy to twist it and hear the signal level change.

Good Luck.

73, Drew KO4MA

-----Original Message-----
From: KC6UQH <kc6uqh@cox.net>
Sent: Jun 21, 2005 1:54 AM
To: amsat-bb@amsat.org
Subject: [amsat-bb] Mode S AO51

I have a down converter and I have tried it with both a  3 Turn Helix and a
patch feed. Both are circular polorization LH.
On F.M. I can get 10 dB of quieting at -120 dB on input to my down converter
I have a S5 noise floor and a S9 on AO-51 on peaks, but loose it for a few
seconds every 9 or 10 seconds.
I can point the feed at a florecent light and get a 2 S unit increase in
noise. I think the converter is O.K.
 The antenna for the bird is linear. Am I to assume that the null is do to
the change in antenna from the bird rotation ?
I now have the feed on a 20 " dish to try to raise the nuls to an exceptable
level without making the pointing critical.
Anyone else had this experience?

Thanks,
Art, KC6UQH
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