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                           Avionics-List Digest Archive
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                     Total Messages Posted Mon 12/09/02: 2
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Today's Message Index:
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     1. 01:30 PM - Re: questions on antennas  (ROBINFLY@aol.com)
     2. 02:47 PM - Re: Re: questions on antennas  (Dennis O'Connor)
 
 
 
________________________________  Message 1  _____________________________________


Time: 01:30:01 PM PST US
From: ROBINFLY@aol.com
Subject: Avionics-List: re: questions on antennas

--> Avionics-List message posted by: ROBINFLY@aol.com

I always have one com that is stronger than the other.  While I have the 
floor board removed (these are bottom mounted antennas), I decided to check 
the contact between the antennas and the skin.  I found the weak com's 
antenna cable was shorted in the connector (so much for the $2K installation 
labor for one GPS/Com w/ new antenna & calbe I paid 2 years ago).  I did not 
remove the antennas, but "ohm" the antenna connectors' shield (ground?) and 
A/C skin and both read .2 ohm.

I also found that when I "ohm" the coax connectors on both antenna (not on 
cable), the weak com antenna has no connection between the center and shield 
(ground?) but the good com antenna reads .4 ohm between the center and 
shield.  Does it sound right?  If the good com antenna and the A/C ground are 
connected (w/ .4 ohm), how can it be the "good" com antenna?

Robin Hou 
E35 Bo,
N7303B






________________________________  Message 2  _____________________________________


Time: 02:47:46 PM PST US
From: "Dennis O'Connor" <doconnor@chartermi.net>
Subject: Re: Avionics-List: re: questions on antennas

--> Avionics-List message posted by: "Dennis O'Connor" <doconnor@chartermi.net>

this is a topic that could become a text book...
First, I suggest that you interchange the antennas to the radios... Move the
weak antenna/coax to the strong com, and the strong antenna/coax to the weak
com and see if anything changes...
Report back and we can discuss it..And yes, both antennas could be fine even
though one shows an open connection for DC and the other shows. 0.4 ohms due
to different internal construction...

Denny
----- Original Message -----
From: <ROBINFLY@aol.com>
Subject: Avionics-List: re: questions on antennas


> --> Avionics-List message posted by: ROBINFLY@aol.com
>
> I always have one com that is stronger than the other.  While I have the
> floor board removed (these are bottom mounted antennas), I decided to
check
> the contact between the antennas and the skin.  I found the weak com's
> antenna cable was shorted in the connector (so much for the $2K
installation
> labor for one GPS/Com w/ new antenna & calbe I paid 2 years ago).  I did
not
> remove the antennas, but "ohm" the antenna connectors' shield (ground?)
and
> A/C skin and both read .2 ohm.
>
> I also found that when I "ohm" the coax connectors on both antenna (not on
> cable), the weak com antenna has no connection between the center and
shield
> (ground?) but the good com antenna reads .4 ohm between the center and
> shield.  Does it sound right?  If the good com antenna and the A/C ground
are
> connected (w/ .4 ohm), how can it be the "good" com antenna?
>
> Robin Hou
> E35 Bo,
> N7303B
>
>