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Echo Flag :         Permanent: N       Export: N      Personal Read: N

 BBS: SWEDX           Conference: SHORTWAVE       Imported:  9/05/1993
  To: ALL                             Num: 8001       Date:  9/02/1993
From: REID KELLY                       Re:            Time:  7:38 am
Subj: Quick-&-Dirty Mw/Lw Loop       Prvt: N          Read: N

  Originally By: Ken Kuzenski
  Originally To: Reid Kelly
  Originally Re: Quick-&-dirty MW/LW loop
  Original Area: Ham_Tech
  Forwarded by : Blue Wave v2.12

on <Aug 27 00:04>, Reid Kelly to Ken Kuzenski said:
 
 RK>>         This is really interesting Ken, if you get a chance 
 RK>> how about doing a complete post about this on the echo? I 
 
Basically, the antenna is a big X, made of two pieces of light wood
(smaller than 1x2"), each about 3.5 feet long.  They're mortised and
held together at the center by a small carriage bolt; two small 
crossbraces a foot from the center provide extra strength.
 
At the end of each piece of the X, a 2" length of 1/8 dowel protrudes
from the wood--this is the form for winding the coil.  The winding begins
at the center of the X, runs out one arm, and begins going around the
form.  I've got about 11.5 turns fairly closewound, but you have to experiment
to get it to resonate where you want.  Where each winding passes over a
dowel, there's a bit of contact cement to hold it in place.
 
The last winding goes around a dowel and runs back to the center of
the X on the arm opposite the one with the other connection.  The two
ends of the windings enter the case of an old digital alarm clock that
also holds a variable capacitor, and a SPST switch.  The switch has a
third wire that runs out to the coil and is connected to the 8th or 9th
wind of wire--switch it closed, and part of the coil is bypassed.
 
There's a crude tuning scale on the face of the alarm-clock case, 
with two scales, one with the switch open and one closed.  :-)
 
As I said, I used about a dozen turns of 22-ga stranded wire, but the
frequency it resonates at is related to many variables (including how
closely wound the turns of wire are.)   What I did is to wind a lot of 
wire, then start taking it off a turn or two at a time, with the variable
cap set about to the middle of the scale.  When I found it resonating
around the bottom end of the BC band, I was in the ballpark.
 
I hope this description makes sense; this really is a very simple 
antenna to build, and it works very well.  Mine tunes from down in
the 350 kHz area to near the top of the BC band; again, what it tunes
is a matter of adjusting the coil windings.  Oh, and there's a dowel 
sticking out of the frame near the center--that fits into what used
to be a swing-arm-lamp arm, which is handy for holding it in just the
right spot.  
 
Some people may be unfamiliar with them, Reid, so I'll note that with
this sort of antenna, there's no direct connection to your radio; you
get it resonant at whatever frequency, and it couples to the ferrite
rod inside the radio.
 
-!- msgedsq 2.1
 ! Origin: Psychotronic BBS (919) 286-4542 (1:3641/1.1)
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