"Cecil Moore" wrote in message
...
A popular myth is developing that the tuner has no effect
at the antenna feedpoint and the only goal is to make the
transmitter "happy". My question is: if we monitored
only the forward current or forward power at the antenna
feedpoint, could we still adjust the tuner? If the answer
is "yes", the myth is false.
--
73, Cecil http://www.w5dxp.com

Everyone makes more of a tuner than what it is. If all transmitters were
designed to work into very wide loads the tuners would not be needed. Tubes
have an impedance of around 1000 to 4000 ohms and must be matched to 50 ohm
coax (usual ham antenna design) or some other combination of resistance and
reactance. The transisitors must be matched from a very low value (under 10
ohms usually) to a higher impedance.
Many transmitters now in use are for only 50 ohm output (fixed tuning) or a
small range (maybe 3:1 for some amps) if they do have an adjustiable
tuning.

There are some antenna designs that fall way out of the 50 ohm design
inpedance so some way must be made to match the inpedances for maximum power
transfer.

Take an amplifier that has a pi-L network built in. If it is adjusted for
max power out , and an amp with a pi network with an external L network to
match an antenna, what is the differance ?