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Old April 21st 06, 06:57 PM posted to rec.radio.shortwave,rec.radio.amateur.antenna
Richard Clark
 
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Default question about tunable capacitor: how to mount ??

On Fri, 21 Apr 2006 18:58:43 +0200, switcher
wrote:

Hi Marc,

Nice pictures by the way.

On the picture, you'll see 7 connections for the cables, oe at the
bottom (7), 6 at the top of the C. How do I need to connect the cables
to have the maximum out of my AM/SW loop antenna ??

http://users.fulladsl.be/spb13810/amloop/tunablec.jpg


You will need a VOM to check, but it appears that numbers 1, 3, 4, 6,
and 7 go to the frame (stator). Screws A, B, C, and D look like
trimmers, not wire attachments (that is, they are small variable caps
in parallel to the main caps).

Numbers 2 and 5 appear to be the main capacitor connections with
reference to the frame. This looks like an old AM tuning component
for which you would have two Caps. One for tuning the front end, the
other for the local oscillator, and the trim caps take care of both
matching the antenna, and keeping the IF tracking between the two
(usually adjusted at the high end of the band). The two main Caps
also have different maximums (because they tune over different ranges
of frequencies).

None of this is of any consequence to you for your project, however.
You need only confirm my guess of the frame connections. If that
bears out, tie them all together, or use just one and ignore the rest.
This is one half of your project's Cap. If 2 and 5 show no continuity
to anything else (except the screw heads, perhaps), then that confirms
their status as being the rotor half of the variable Cap. Tie them
together for the other half of your project Cap.

If there is any variation in testing with the VOM for continuity, you
may have a split frame. Visual inspection should reveal two
assemblies that would be very similar in construction. Take hints
from discussion above to reduce the complexity of all the leads.

73's
Richard Clark, KB7QHC