Re: R.S. trimmers


From: Daniel J. Curtin (
Date: Mon Feb 14 1994 - 13:02:14 EST

        You could put one in series with a fixed value cap (NP0 perhaps for
stability) to bring down the lower value. E.g., a 100 pF cap would give a range
of about 49-80pF, if I have punched the buttons on my calculator correctly. I
have often done this to modify the range of a variable cap I have on hand. I am
sure in a very critical application this could present problems, say if the
currents were relatively high and the cap shifted due to heat.

Dan, KF4AV

Daniel J. Curtin
Department of Mathematics and Computer Science
Northern Kentucky University
Highland Heights, KY 41099-1700

_._ .._. ...._ ._ ..._

=> Just for your info, Radio Shack carries a 95-420 pf trimmer capacitor
=>for $1.85 ('93 catalog). Specs: compression type, dielectric strength
=>100vdc for one minute, Q greater than 500 at 1 MHz, 7/8 x 3/8 inches.
=> A couple of these are going into my new 30M xmtr project; hope they
=>work okay; I'll let you know.

95 pf is pretty high for HF projects, isn't it? How to you
get/make coils with the low mH required?

Randall Rhea Informix Software, Inc.
Project Manager, MIS Sales/Marketing Systems

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