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Re: Topband: Antenna switch rating for high SWR?

To: topband@contesting.com
Subject: Re: Topband: Antenna switch rating for high SWR?
From: "Joe Subich, W4TV" <lists@subich.com>
Date: Sun, 20 Oct 2013 12:57:58 -0400
List-post: <topband@contesting.com">mailto:topband@contesting.com>

I know that T/R switches inside amps are fairly small in physical
size, however they are designed to operate into a fairly low SWR
load. I have no idea of what rating of a DPDT switch I would need
(per the diagram) in my application - perhaps I'm making a bigger
deal of something that isn't so critical.?

Fire up ELNEC or your favorite modelling software and run your
specific combination of flat-top length/height and feeder length
to find out what the voltage and current are at the input of the
feed line.  That will tell you what you need for the relay.

Remember, you can use *TWO* high voltage/high current "contactors"
and mount them on Lexan or similar non-conducting surface to increase
the voltage to ground rating if necessary.

73,

   ... Joe, W4TV


On 10/20/2013 12:04 PM, John Harper wrote:
Morning all,



I am planning to put in a DPDT switch (or relay) to allow me to easily
switch from using my 80m dipole as a vertical (T-top) antenna on 160m:

http://www.ae5x.com/docs/antennas/160mT.jpg



The dipole is fed with 450-ohm ladder line and used 10-80m in that
configuration so there is a high SWR on the line. I sometimes use a kw
output.



I know that T/R switches inside amps are fairly small in physical size,
however they are designed to operate into a fairly low SWR load. I have no
idea of what rating of a DPDT switch I would need (per the diagram) in my
application - perhaps I'm making a bigger deal of something that isn't so
critical.?



John AE5X

http://www.ae5x.com/blog



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