Good points, my 30S-1 has load and tune still in it and the final a
3CX1500B is ceramic and can't be seen but it never lost it's Eimac stencil.
However my Collins 30L-1 was a different story. Once or twice I had 811As
with holes melted in their plate structure. They continued to work well and
I always thought this was from overdriving but now I'm not so sure because
it ran at the same high swr as the 30S-1. I used the 30L-1 in summer
because the air conditioner couldn't keep up with the heat generated by the
30S-1 so it was my winter amp.
I notice that Walt Maxwell's Reflections II was published by World Radio
whereas Reflections was by the ARRL. There is some disagreement on
"conjugate match' and probably other things between ARRL and Walt. So now I
have to wonder if the final tube is dissipative or non-dissipative for
reflections.

Looks like my new thread isn't working but I'm posting this to it just in
case since I don't really know the customary protocol on a long thread that
sometime digresses.

--
73
Hank WD5JFR
"Richard Clark" wrote in message
news
On Tue, 25 May 2004 16:12:05 GMT, "Henry Kolesnik"
wrote:
Before it came down my 20 meter antenna had a SWR approaching 20:1 and I
was
running a Collins 30S-1 and no tuner!. I did that for several years and
would be still doing if the roofers hadn't destroyed ~130 ft. dipole.
One
of these days after my back improves I'll put another one up.

Hi Hank,

I used to teach this Collins equipment in the Navy. I presume yours
had a finals tuning circuit still in it? Hard to imagine it
otherwise.

Tubes are different from transistors only by approaching the Source Z
with an inverted ratio of transformation. Ever hear of plate
resistance? It is literal resistance. Ever see a plate glow when
under the stress of hi SWR? It is literal heat. The same heat is
generated irrespective of it being explained by wave mechanics or
lumped equivalent circuits. Choose the model you are comfortable
with, and then tackle the SWR if you care about efficiency.

If anything, tube sets prove the problem of reflected power through
your ability to directly observe the heat generated and experience the
cost of new finals tubes through their degraded life span. This stuff
is all rote teaching; and my students were given practical tests to
troubleshoot, tune, and repair against such scenarios.

I've had hands-on experience with this topic both academically and at
several benches - the sophistries that deny these points are amusing,
but remain amateur scribblings.

73's
Richard Clark, KB7QHC