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Topband: Q of inductors

To: Top Band Reflector <topband@contesting.com>
Subject: Topband: Q of inductors
From: Roger D Johnson <n1rj@roadrunner.com>
Date: Fri, 31 Aug 2007 09:34:06 -0400
List-post: <mailto:topband@contesting.com>
A while back I purchased a Collins 180L-2 coupler with
the idea of using the rotary inductor and vacuum variable
in an antenna coupler project.

I took out my trusty GR 1606 bridge to measure the inductor
and it seems that the Q is only about 160! I had expected the
ribbon inductor to be higher. Further investigation revealed
that the unit had a large ferrite slug in the middle. I removed
the ferrite since I didn't need the full 40 uH of inductance
and I didn't know if it would withstand 1200 watts which I
intend to use. I fixed some problems with the contacts but the
Q is still about 160 with an RF resistance of approx 2.5 Ohms.
For comparison, a 28uH rotary measures about 210 and
a piece of Miniductor is over 300. Are my measurements on
target?

73, Roger

-- 
Remember the USS Liberty (AGTR-5)
http://ussliberty.org/
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