[Towertalk] Force 12 antennas and tower relay grounding

[Guy Olinger, K2AV]

Suggest that you get on force12talk@qth.com, subscribe if you need to
and pose the question. Natan reads the reflector and often answers
these kinds of questions.

When you have feedlines attached to these driven elements that are
closely coupled, and depending on how long the feedline is to the
particular DE, the unused DE's can appear either open at the center,
shorted at the center, or worse, detuned to some odd frequency that
affects another band.

You need to know from F12 whether the design wants the unused DE's to
be shorted or open, and design the feed length to the switch and
choice of open/shorted when not in use to match.

When putting these kinds up on a complex model, the characteristics
can change with an unfortunate choice.

Good Luck, Guy.


----- Original Message -----
From: "Henrik Weiss" <ozling@mail.dk>
To: "Towertalk@Contesting. Com" <towertalk@contesting.com>
Sent: Monday, March 25, 2002 2:24 PM
Subject: [Towertalk] Force 12 antennas and tower relay grounding


> I am about to put up an Ameritron RCS - 8V remote 5 position coax
relay
> switch on the tower. I will put up Force 12 antennas in the coming
weeks and
> would like to know :
>
> Shall I ground the unused antenna relays or let them flow isolated
and does
> it matter in terms of antenna radiation pattern. I guess grounding
is safest
> in terms of lightning !! but I may ground part of the antenna which
may not
> be good.
>
> The antennas are the 5BA which incorporates 3 seperate feedlines on
the same
> boom for the higher bands and the 2 element 40 and 30 meter
interlaced yagi
> with two feedlines on the same boom.
>
> Thanks in advance,
>
> Henrik
> OZ1ING
>
>
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