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[TowerTalk] balanced line loss on a mismatched antenna

To: TowerTalk <>
Subject: [TowerTalk] balanced line loss on a mismatched antenna
From: Gary Slagel <>
Reply-to: Gary Slagel <>
Date: Mon, 27 Feb 2012 15:07:14 -0800 (PST)
List-post: <">>
 Hi all,

I need some input on line loss when using 450 ohm balanced line to feed a 
mismatched antenna.

According to an online loss calculator, if I have a 150ft run of 450 ohm 
balanced line and an SWR of 100 to 1 I have about 3.5 db of loss at 7.0 mhz.  
If I have a 10 to 1 SWR that same feedline will have about a .5 DBI loss.  I'm 
thinking of a w8jk style antenna that has 2 44ft elements on a 16ft boom fed 
with 450 ohm balanced line for 40 meters.  EZNEC says the swr at the antenna 
will be over 100 to 1.  I think I can tune the antenna with the feedline and 
get it down to a more reasonable level, maybe 10 to 1, at the tuner end.  Then 
the tuner will tune it to resonance so the xmttr can put its full load into.  

Question is, since the swr is 10 to 1 at the radio end of the feedline but 100 
to 1 at the antenna end of the feedline, am I going to see the 3.5 db loss from 
a100 to 1 swr or the .5 dbi that a 10 to 1 swr would give me. 

Thanks for your input!

Gary Slagel

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