Topband: Toploaded vertical - SWR

[Don Kirk]

Hi Clive,

Nothing wrong with the hairpin as you mentioned which I really consider to
be a high pass L network (which N3QE eluded to) in which the L network
capacitance is provided by the antenna (you have to actually shorten the
antenna from its resonance dimension in order to provide the required
capacitance, and it is a precise value of capacitance you need in order to
provide a "perfect match" in conjunction with the precise value of hairpin
inductance that's required for the "perfect match").

Great discussion with numerous approaches.

73,
Don (wd8dsb)

On Wed, Sep 19, 2018 at 1:46 PM Clive GM3POI <clive at gm3poi.com> wrote:

> What I don't understand is why would you use more components than needed.
> Why a capacitor (possibly vacuum). What is wrong in using a hairpin which
> also DC shorts the vertical to ground.  A combination of hairpin size and
> top loading will give you 1:1 at your favourite 1.825 or anywhere else.
> Perhaps WX0B's article needs a reprint in the NCJ. It really is simple just
> a few microhenries of inductance and you are done.
> 73 Clive GM3POI
>
> -----Original Message-----
> From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of Don
> Kirk
> Sent: 19 September 2018 17:29
> To: Herbert Schoenbohm
> Cc: topband; ash.kf5eyy at gmail.com
> Subject: Re: Topband: Toploaded vertical - SWR
>
> >
> > Herb (KV4FZ) mentioned an L network, and that is what I always use.  Very
> > simple, and you just plug you're measured complex impedance values (at
> the
> > frequency you want to be resonant) into one of the many online L network
> > calculators to determine the amount of inductance and capacitance
> required
> > for the L network.  I normally just wind my own coil for the inductance,
> > and use high voltage silver mica caps for the capacitor.
> >
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