[TowerTalk] Loading a Pro-AM 160M on other bands?

Dan Zimmerman N3OX n3ox at n3ox.net
Fri Feb 16 13:24:49 EST 2007

>Is the coil and feed system on such a vertical
>such that trying to load it on 80, 40, 20, etc.
>via an antenna tuner is a waste of time?

Yes.  The load and antenna impedance are such that the coil reactance goes
up while the antenna reactance goes down in frequency.  What you end up with
is that the loading structures act more or less as an RF choke if you get
significantly above resonance.  This doesn't happen with a simple wire

For small frequency excursions, it's OK... if you want to load a vertical to
operate on 1800kHz and then use a large variable capacitor to tune it across
the 160m band, that's not so bad (but requires a sort of massive capacitor)

If you want to operate a loaded vertical at a much higher frequency, what
you want is to reduce the loading coil inductance.

You don't want to use a tuner.


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