[AMRadio] antenna tuners

Gary Schafer garyschafer at comcast.net
Fri Apr 21 22:29:58 EDT 2006

> -----Original Message-----
> From: amradio-bounces at mailman.qth.net [mailto:amradio-
> bounces at mailman.qth.net] On Behalf Of Donald Chester
> Sent: Friday, April 21, 2006 7:56 PM
> To: amradio at mailman.qth.net
> Subject: Re: [AMRadio] antenna tuners
> > > I don't believe in them.
> > >
> > > If you can't resonate your antenna, then what are you doing?
> I prefer to use just one dipole, centre-fed with open wire line, and use
> multiband tuners to operate that same antenna on several bands.  That way
> it
> is uniformly efficient all the way across each band, and I don't have the
> clutter of multiple dipoles strung all around each other, or the
> compromise
> of an "all-band" antenna such as a trap dipole.
> With a proper tuner, the antenna, feedline and ATU all make up a resonant
> system.  Resonance can be changed by changing the length of the antenna,
> the
> length of the feedline, or the adjustment of the tuner, but it's the whole
> system that is placed in resonance, not just the antenna wire itself, as
> in
> the case of a simple coax-fed dipole.
> Don k4kyv

Hi Don,

Let's say you changed the output impedance of your transmitter from 50 ohms
to say 200 ohms. (changing nothing on the tuner) Would the "antenna system"
(antenna, feed line and tuner) still be "resonant" as you had them tuned
when you had the transmitter set for 50 ohms output?

If you now retune the antenna tuner to accommodate the 200 ohm output of the
transmitter, will the "antenna system" again be resonant? :>)

Gary K4FMX

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