[Elecraft] Now General RF Issue WAS 160m loop experiment a big failure

[Mel Farrer]

Take a antenna analyzer and put it at the end of the coax.  Regardless of the reading, run your hand up and down the outside of the coax.  If the shield is open or bad, the readings will go all over the place.  


Mel



________________________________
From: Ian White GM3SEK <gm3sek at ifwtech.co.uk>
To: elecraft at mailman.qth.net
Sent: Friday, October 21, 2011 1:12 PM
Subject: Re: [Elecraft] Now General RF Issue WAS 160m loop experiment a big failure


As Jim Brown says: if all these problems came on suddenly, focus on what 
parts of the installation have CHANGED.

You may well have identified one:

>
>Right now I am thinking that I have a bad coax line outside of the 
>house.  The reason for this is that I had a new propane tank installed 
>and they needed to back the truck up and had to drive over the buried 
>coax.  I did put boards down to spread out the load and protect the 
>lawn and also the coax.  However the problem has started since this 
>incident.
>
>I pulled the coax out of the ground and it has bend marks at the edges 
>where the boards were which to means that it was deformed and maybe it 
>is now crushed.
>

Is there any chance that the shield has been pulled apart, and is now 
completely open-circuit? A broken shield connection can be a major cause 
of RFI, as RF currents can appear in very odd places in their search for 
a new return path.

How would a TDR respond to a broken shield? "Installation-dependent", I 
suppose...


-- 

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
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