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Re: [TowerTalk] SWR is what SWR meter measures

To: <garyschafer@comcast.net>, "Tom Rauch" <w8ji@contesting.com>
Subject: Re: [TowerTalk] SWR is what SWR meter measures
From: "Jim Lux" <jimlux@earthlink.net>
Date: Thu, 12 May 2005 21:10:52 -0700
List-post: <mailto:towertalk@contesting.com>
<monster snip>
> >
> > 73 Tom
> >
>
> I agree with Tom about reflected power not being dissipated in the
> transmitters final. For all practical purposes, it all gets returned to
> the antenna and radiated except for the small amount of loss the
> transmission line causes from the mismatch.

For a tube amp, sure.  And for a solid state amp with a tuner on the output.
But not for a broadband SS amp, in general.  While they're not 50 ohm
resistive, they're also probably not too far away, so the mismatch at the TX
output isn't going to be all that huge.  If there's not a big mismatch, most
of the reflected power winds up "inside" the TX, and gets dissipated (or fed
back into the power supply, if you've got an amplifier that can do that).

>
> If a tuner was in line and matched the transmitter would never see any
> reflected power. The tuner does not absorb the reflected power but
> reflects it back to the antenna.

exactly..


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