Yes, Tom. You need that dual-section (not quad section!) differential
variable capacitor to make a replica of the Johnson Matchbox "tuner"!
My father built a replica, using home-made plates, shaft, end plates, etc.
for the differential capacitor and hand-wound a variable-pitch, variable
diameter coil (link-coupled, of course) to optimize it for 10M down to the
bottom end of 80M. It worked like a gem and would match an even wider range
of impedances than the "original" Matchbox !! He also made it capable of
high-power operation (before the days of the "Kilowatt Matchbox"), so I
could even use it with my push-pull 304TL's on 20M !! Regrettably, it got
sold along with my high-power, rack-mounted amplifier! I sure do wish I had
it today!
Karl K - W8TIF
McKinney, Texas
-----Original Message-----
From: Tom Scott [mailto:tscott@eni.net]
Sent: Saturday, December 04, 1999 4:39 PM
To: Low Power Amateur Radio Discussion
Subject: Air Variable Cap kits?...
Does anyone out there know of any remaining supplier that either makes air
cap kits or custom air caps?
Alternatively my Dad tells me that he remembered an advertiser in the back
of QST who offered air caps that were assembled in such a way that it looked
like the rotor plates might be taken apart.
I have a project that could use a quad section air cap made up of two
isolated dual differential air caps. Low voltage receiver size is adequate.
If I could find one that can be taken apart and put back together
differential style, that would work. Failing that, I guess I can make one
from scratch, just a lot of work.
(Anyone care to hazard a guess what that'd be for?)
- Tom
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?Tom Scott - Wyle Electronics - KD7DMH
10300 SW Nimbus Ave #PB, Portland, OR 97223
503-603-1931 - Tel 503-684-6620 - Fax
503-703-2032 - Cell
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