Thread: Grid Dip Meters
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Old November 22nd 03, 01:50 PM
Michael A. Terrell
 
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J M Noeding wrote:

On Mon, 17 Nov 2003 13:55:19 +0000, Paul Burridge
wrote:

On Sun, 16 Nov 2003 22:33:38 GMT, (J M Noeding)
wrote:

Maybe you have a different model. Mine purports to cover up to 360Mhz,
but there is *no way* AFAICS that the thing would be capable of
anything remotely close to that upper range limit, on cursory
inspection of the internals. I'm glad I went for the wholesale
re-build but still find it hopelessly impractical to use on minature,
in-circuit components.


Can only agree very much to your comment "there is *no way* AFAICS
that the thing would be capable of anything remotely close to that
upper range limit", whether the upper limit is 280 or 360MHz becomes
less important when it actually don't operate properly above 140MHz

But I don't see that an instrument intended to cover down to 500kHz
could have practical variable capacitor for UHF, so somewhere should
be another construction. Perhaps an idea to look at DL7QY microwave
dipmeter.... I might consider copying some of his details to a web
page

73
Jan-Martin
LA8AK
Instruments:
http://home.online.no/~la8ak/m1.htm (and -.m2.htm)
Homebrew instruments: http://home.online.no/~la8ak/m3.htm
Homebrew audio instruments: http://home.online.no/~la8ak/m31.htm
--
remove ,xnd to reply (Spam precaution!)


You can use a capacitor in series with the variable capacitor to reduce
the tuning range, but you would need a switch to select the high or low
capacitance range, and to move the coil connection to the active
components. That, or use a dual capacitor, build two circuits, and
select one oscillator at a time.
--
I say, the boy is so stupid that he tried to make a back up copy of his
hard drive on the Xerox machine!

Michael A. Terrell
Central Florida