"Cecil Moore" wrote in message
...
James Barrett wrote:
So a tuner is really there to protect the transmitter.

It does that by not allowing reflected energy to
reach the transmitter and redistributing the
reflected energy back toward the antenna as
part of the forward wave. Thus a transmitter can
be sourcing 100 watts while the forward power
on the transmission line is 200 watts.

What it really is is an impedance matching network. You adjust the antenna
tuner so that the transmitter sees 50 Ohms. If your SWR meter is calibrated
for 50 Ohms, that means an SWR of 1:1 (between the tuner and the radio).

You still need the wire cut to frequency if you
want to maximize efficiency and minimize the SWR in the wire.

Efficiency can also be maximized by choosing a
near-lossless transmission line. In that case,
SWR doesn't necessarily need to be minimized.
--
You mean the SWR doesn't have to be minimized on the transmission line. If
you don't have a tuner and run a 600 Ohm transmission line into the
transmitter, it will be happy at an SWR of 12:1 if the impedance the
transmitter sees is 50 Ohms. On the other hand, with 600 Ohm line, and an
SWR of 1:1 the transmitter will barf.

The longer wire is usually better than the short. Also, the ARRL recommends
a length that is not resonant on any band to make the job of the antenna
tuner easier. Wires around 100 feet are often used.

Tam/WB2TT

73, Cecil http://www.w5dxp.com