Topband: Capacitor Hat / Vertical

[Ken]

Hello Top Band,

Thank you all for replying to my message.  It is great to hear all of these
inputs.  Some are saying yes, some are saying no to the question about
adding a variable capacitor at the top of a vertical.

Please keep in mind; I will be adding a top hat made up of 8 radials, each
being 7 feet long.  (Forget the stinger)

I know when a capacitor is in series, it will divide, and when it is in
parallel it will double, as others had mentioned.

Some are saying that this idea will not work; due to the cap being in series
with the vertical will decrease the capacitance.

What about a variable capacitor in series with the feed line at the base of
the antenna, is this capacitance being divided or doubled?

The saying goes, for a short vertical, it will need top loaded capacitance.
I would like to think by adding a variable cap to the top will add
capacitance to the antenna.

Why is this not the case, and if it has something to do with it being in
series, how about in parallel then??

Thank you,
Ken
K3YI



Hello,
>
> Not being the smartest Ham in the shack!  Talk (theory) has it, that when
> Using a short vertical here on top band, a lot of top loading capacitance
> is
> needed to bring the s.w.r. to resonates.  That is by use of a top radial
> hat
> or several yagi antennas to be mounted at the top of the vertical antenna.
>
> With that said, is it possible to mount an insulated box at the top of the
> mast and have a 1000PF variable capacitor installed inside.  Having a wire
> coming off the end of the vertical mast going to one end of the variable
> and
> then having another wire coming off the other end of the variable to a
> stinger that is insulated mounted on the end of the vertical mast.
>
> Then remotely tune the capacitor for resonates.
>
> The real question is, will this work as long as it is enough capacitance?
> How can one determined the amount of capacitance that is needed?
>
> Thank you!