At 11:47 PM 12/5/97 -0500, you wrote:
>Hey all. Ran a bit of the 160 contest tonight and noticed that after
>about 45 minutes of heavy use power output started falling off on
>my homebrew 3 x 4-500 amp. The input SWR isn't changing but
>the output tuning seems to be effected. After 5 minutes cool off
>its back up to full legal output. Could the plate blocking caps, a
>pair of TV door knob types, be the culprit? Any ideas?
>
> 73 de Walt Kornienko - K2WK - zak@goes.com
More than likely Walt, it is the padder cap on your loading variable
cap. A small doorknob is not rated for the kind of current you are
putting through it. The Alpha 77SX has this same problem. Replacing
the padder cap. with two caps of 1/2 the original value in parallel
will solve the problem. If you have room, you can put in 4 caps of
1/4 the value taken out. GL! Also TV doorknobs are not RF rated but
don't let the word get out as a lot of us have been violating the
rules of nature for many years. If you operate a lot of 10-12-15
meters, I would install a glitch resister in the B+ lead as the
TV doorknobs will short sooner or later.
(((73)))
Phil, K5PC
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