"Thierry" To answer me in private use http://www.astrosurf.com/lombry/post.htm wrote in message ...
"Cecil Moore" wrote in message
...
JDer8745 wrote:
It's funny that this old wive's tale about the high SWR "burning out the
finals" still exists. I guess it depends on what the meaning of "high"
is.

If high SWR and the attendant mismatch cannot burn out a final,
I wonder why most commercial finals are protected from a high SWR
by foldback circuitry to avoid damage to the finals?

Indeed.
I always hear and read that a high SWR can destroy the PA final of TX,
cranck coils, etc.

Thierry

I may be confused now after reading all the posts, but if you have a
good SWR on the rig that is driving an amp, this is normal, even with
a mismatch to the amp. The amp probably has a tuned input circuit.
It's not going to change much if any, if the SWR to the amp goes high.
Or I don't believe anyway...You should run a meter before the amp, on
the antenna side, to also measure the SWR to the amp. The meter in the
rig is just looking at the tuned input circuit of the amp. You need
another one if you want to keep the amp happy. A solid state amp is
much more critical than the tube amps as far as SWR. But I still
prefer to keep a tube amp under 2 to 1, unless I lower the power
level. But I've run 3:1 or worse many times with my henry 2K classic,
and it never complained. As long as you are within the loading range
of the amp, it's perfectly fine. I think the tubes do run a bit hotter
if the SWR is excessive. Thats why I'll drop the power a bit. When I
do run the amp, I almost always have a good match, IE: coax fed
dipoles, yagis, etc... and I almost never use a tuner. I haven't
actually run my amp in about 4 years. I have it dismantled, and have
been too lazy to order new caps and out it back together. I really
don't need it most of the time. It's handy if I want to brown the food
in a certain area.
MK