[IRCA] Copper loop update

["Craig Healy" <bubba@xxxxxxxxxxxxxxxxxxxx>]

I had a chance to do a fair bit more experimenting with that loop tonight.

As a recap, this is a single turn loop made with four 10' sections of 3/4"
copper tubing soldered with 90° elbows into a square.  I have a ferrite
toroid through which one copper tube passes.  There are about six turns of
#16 wire as an output link on the ferrite core.  The six turn figure was
pulled out of thin air, and I need to try more and maybe less turns to
optimize it.

Tonight I decided to not use the tuner, and connected the RG-8 coax directly
to the R8B input.  Wow!  With the radio preamp on, I had good signals across
the band.  I put the loop out in the back yard away from the tower and other
metal objects.  I haven't made a mount yet, so I just jammed it into a bush
to keep it from falling over.  It is roughly broadside to Boston.  Setup is:
Loop-Ferrite Transformer-RG-8 Coax to radio.  Dead simple.

What I found was some significant nulling.  WEEI-850 Boston was reduced to
background interference to WREF and oldies.  Stayed very consistent.  I was
able to hear WSBS-860 in Great Barrington, MA with Mohegan Sun ads, and a
good ID right before sunset.  WSBS is a *very* tough station to hear despite
it's close distance.  Just doesn't get out well in this direction.

I tried moving it to null NYC, and found country music way over an nearly
non-existent WINS-1010.  No ID, but likely NH.  Noise under WCBS-880.  All
NYC stations reduced a noticeable amount.

Also tried down into longwave, and got a number of beacons.  Shortwave in
the 75m ham band, and 41m SWBC band was also good.

So, next thing is to build a real rotatable mount for it, and do a much more
scientific test to see just how well it nulls.  I am quite pleased so far.
This has the potential for being mounted on a rotor in the clear somewhere.

As I mentioned earlier, I may build two smaller ones and fix-mount them at
right angles to each other and use the MFJ-1026 to see how that nulls.
Later..

Craig Healy
Providence, RI


_______________________________________________
IRCA mailing list
IRCA@xxxxxxxxxxxxxxxx
http://dallas.hard-core-dx.com/mailman/listinfo/irca

Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers

For more information: http://www.ircaonline.org

To Post a message: irca@xxxxxxxxxxxxxxxx