[Antennas] From transmission lines to tuners

[N7WS]

At 08:50 12/21/02 -0800, Steve L. wrote:
>
>> A KW into a tuner with 60% loss means that the tuner
>> must dissipate
>> 600 watts - not likely.
>
>This has been my 'bull$hit' touchstone for many years.
>
>
>My Alpha 99 with the optional cooling fan can TX a
>continuous 1500W output forever. I've sent 5-6 minute
>continuous RTTY transmissions at that power level many
>times over a few hours... and I can't feel any rise of
>temp in the transmatch except the ferrite balun. I can
>easily leave my hand firmly gripped onto the balun and
>wires after that transmission.... meaning we are
>dealing with what, 25W? Out of 1500?
>
>I do use a massive edge-wound silver-plated rotary
>inductor from Pal Star (get one, they rock!) and real
>antennas of the proper size for the band -- not 1/10
>wavelength things and I homebrew my baluns from really
>big wire and lots of cores.

So, your situation is entirely different from the norm.  In fact it appears
that you might not even need the tuner.

A lot of comtemporary tuners use small inductors, a bunch of switched fixed
value capacitors and modest variable capacitors.  The built-in tuner in my
TS-870 has 1 dB insertion loss into a dummy load!

The average guy who has bought into the magic ladder line fed antenna is
*not* using a tuner with edge-wound silver-plated inductors, but something
like a mighty fine junk tuner and he's feeding a forty-meter dipole on 80
meters.

The only reason his doesn't burn up is the fact that the transmit duty
cycle is probably about 10-20% for the average operation if you figure
receive times and the low duty cycle of both SSB and CW.
>
>Not that crappy efficiency can't happen, it can, but
>when you can't feel any heat rise inside the
>transmatch it's a big hint. Try holding onto a 100W
>incandescent light bulb! (don't).
>
>rant off

Why are you ranting.  Can't we hold a civilized technical discussion :)

Wes Stewart  N7WS