----- Original Message -----
From: <k6se@juno.com>
To: <topband@contesting.com>
Sent: Tuesday, August 05, 2003 3:24 PM
Subject: Re: Topband: Shunt Fed Tower Info
> Regarding floating elements be aware that the driven element, although
> insulated from the boom, acts like it is grounded to the boom on 160m
> because of the feedline's coupling to the tower on its way down to the
> ground. Therefore, the driven element already fully adds to the
> top-loading and there is no reason to "ground" the driven element to the
> boom when you shunt feed the tower on 160m.
When I was using a shunt fed tower with a KLM 40 meter beam on top, I set
the feed line on fire where it was taped to the boom. I grounded all the
elements, including the DE.
John k9dx
> As Tom, W8JI pointed out, it is wise to ground the parasitic elements to
> the boom because of the high RF voltages present, especially at the ends
> of the boom. Several hams have had arcing problems from the 20-meter
> reflector element to the boom on Force 12 beams when they used their
> shunt-fed towers on 160m. They solved the problem by grounding the
> parasitic elements to the boom.
>
> If you ground the parasitic elements your tower will have substantially
> more top loading, therefore the shunt feed parameters will be quite
> different than with insulated parasitic elements.
>
> 73, de Earl, K6SE
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