"Charles Schuler" wrote in message
. ..

"billcalley" wrote in message
oups.com...
What I gleaned from the excellent answers for the original "VSWR
Doesn't Matter?" thread is that high VSWR doesn't really matter in a
lossless transmission line environment between a transmitter's antenna
tuner and the antenna, since any reflected RF energy will simply
continue to "bounce" back and forth between the tuner's output
impedance and the antenna's input impedance until it is, finally,
completely radiated from the antenna without loss.

That's basically true but ignores the stress that can be placed on the
output circuit of the transmitter. Why do you think VSWR shut-down
circuits are so popular? One can see rather high voltages or currents
that are potentially damaging to the transistors and capacitors.

Now, since "lossless" is an abstraction and all materials have voltage and
current limits, just make this easy on yourself and always strive for a
VSWR of 2:1 or less. It simply works better and is more reliable.

If a tuner is placed directly after the TX and properly adjusted the TX
will always see a 50 ohm load and the shutdown circuit will always be
happpy. Again as long as the TX sees a match there is no unusual stress
placed on it. Remember that before the invention of coax cable SWR was
rarely considered. Instead the tx was tuned for proper established
operational parametrs and all was right with the world.

1:1 SWR CAN MEAN YOUR COAX IS FULL OF WATER.

Jimmie