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Re: [TowerTalk] switching open wire lines

Subject: Re: [TowerTalk] switching open wire lines
From: jim Jarvis <>
Date: Fri, 11 Apr 2008 22:35:19 -0400
List-post: <">>
In my comments regarding phantomed relay switching of the feedline,   
I did not consider the
higher impedance situations.   Gary is quite correct, in his  
observation (below).  It's
of greater concern if the plan is to drive the antenna in modes where  
the feedline
sees >600 ohms.    Like an 80m dipole fed on 40m, which would have 2k  
or so.    Voltage breakdown would become a significant factor.



You will want to have something better than the type of relay used to  
50 ohm coax though. 1500 watts at 50 ohms is 273 volts. 1500 watts at  
ohms is 948 volts and that is providing the swr is 1:1.

Gary  K4FMX


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