[TowerTalk] DPDT Coaxial Relay question or alternative

[D. Scott MacKenzie]

I don't follow - could you explain it to me?

Thanks

Scott

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com]On Behalf Of David Gilbert
Sent: Sunday, April 08, 2007 12:33 PM
To: Clint Talmadge
Cc: TowerTalk
Subject: Re: [TowerTalk] DPDT Coaxial Relay question or alternative



Hi, Cliff.

To change from broadside to endfire you need 180 degrees phase shift,
not 90 degrees.  You can get that with either a half wavelength of coax
(adjusted for velocity factor) coax or by switching the connections (an
inexpensive 12v DPDT automotive relay from Auto Zone works fine) on the
output side of one of the choke ununs you should be using to feed the
verticals anyway.

73,
Dave   AB7E



Clint Talmadge wrote:
> I am building a set of Phased verticals for 30M. I was going to switch in
a quarter wave length of coax using a DPDT coaxial relay, to steer the
signal 90 degrees (Broad side to End fire). I went looking for the
appropriate relay and found some (Surplus Sales) but the cost was more than
I have in the two verticals and the cabling. Does anyone have an inexpensive
source for one or an idea on how I might do it with a "regular" DPDT relay?
I have some Potter Brumfield that will take the power but how much impedance
"bump" will that insert and should I worry about it?
>
>
>
> Ideas and suggestion are welcome.
>
>
>
> Clint - W5CPT
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