On Apr 19, 2006, at 12:27 PM, Darwin, Keith wrote:
Last night I tried it again and noticed the resonant frequency had
shifted from 7.040 to 9 MHz.
I fought a problem like this with my shunt-fed tower for 80 and 160m.
Plagued me for months. I finally figured out the problem -- the
toroid that formed part of the matching network was arcing.
This toroid was two T200-2 cores stacked with 44 turns tapped every
two turns. The starting and ending turns were adjacent and that's
where the arcing took place. The auto-transformer action of the
tapped matching network caused the arc.
I solved the problem by switching to two different inductors, one for
the 80m and one for the 160m matching network. The 160m inductor is
now 40 turns on the two T200-2 cores, and there's some space between
the starting and ending windings.
Arcing problems like this may not be evident at the 20 watts or so of
the auto-tuner of the K2/100, but show up with 50 or more watts.
Intermittent problems of this sort are difficult to track down.
Inspect everything.
Bill Coleman, AA4LR, PP-ASEL Mail: [EMAIL PROTECTED]
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901
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