Re: TC Grid Dip Oscillator?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Peter Lawrence by way of Terry Fritz <teslalist-at-qwest-dot-net>" <Peter.Lawrence-at-Sun.COM>

Matt,
      I've been thinking about building this dip meter:

   <http://users.tpg-dot-com.au/users/ldbutler/NegResDipMeter.htm>

but I'll have to understand it first to extend its freq range down
to typical TCs. Let us know which one you build and how it works.

-Pete Lawrence.

 >
 >Original poster: "Matthew Smith by way of Terry Fritz <teslalist-at-qwest-dot-net>"
<matt-at-kbc-dot-net.au>
 >
 >Hi
 >
 >I remember a discussion earlier this year which I don't seem to be able to
 >track down in the archives.
 >
 >There was some talk of using something like a grid dip oscillator for TC
 >tuning - it seemed that the variable capacitors involved were becoming very
 >scarce.
 >
 >I have how acquired two very nice (to look at) variable caps, date stamped
 >1977 and aparently unused.  They are single gang, but the shafts come out
 >either end so it wouldn't be any great trouble to couple them together.  My
 >Wavetek DMM tells me that they are about 200pF each and the spacing of the
 >platess makes them look like they'd take a respectable voltage.  (About
 >1.8mm, although it's hard to get an accurate measurement as the plates flex
 >when the caliper touches them; shades of Heisenberg ;-)
 >
 >So, what's the circuit that I should put these into?  My copy of Eagle is
 >open and ready to go...
 >
 >Cheers
 >
 >M
 >
 >--
 >Matthew Smith
 >IT Consultant - KBC, South Australia
 >KBC Web Site    http://www.kbc-dot-net.au
 >PGP Public Key  http://gpg.mss.cx
 >
 >
 >