[TowerTalk] Grounding mast?
RadioIR at charter.net
Wed Jul 30 17:23:10 EDT 2008
N2TK wrote ...."Even without grounding the elements I can move the SWR
on 160 all over the place with running the elements in and out on the
That would agree with NEC simulation. Even when elements are not
connected to the tower, they will provide some amount of top loading,
although not nearly as much as when they are connected. The unknown is
the amount of RF current flowing across the stray capacitance between
primary and secondary of the balun in the driven element, and also the
amount of the voltage drop from primary to secondary across this balun,
and whether that is enough to damage the balun. This is one of the main
reasons I decided to not shunt feed my tower. Everyone's installation
is different so it is difficult to generalize what the results will be.
I would be interested in knowing if you are running high power on 160.
>I found I had some intermittent changes in SWR on 160M (shunt feeding the
>tower). I put a grounding strap from the mast to the top of the tower
>(across the TB-3). SWR has been stable since. Have not bothered to put a
>ground strap across the Prosistel.
>Have a MonstIR. Was going to short out the passive elements to the boom. But
>I am getting the 60/80M add-on kit so won't be able to do that except for
>the 1st Director. Will ground that and see what it does for top loading on
>160M. Even without grounding the elements I can move the SWR on 160 all over
>the place with running the elements in and out on the MonstIR. There seems
>to be no arcing or sputtering so far on topband.
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