Congratulations on building your first loop.
Is there a URL for this particular loop design you used?
How is the loop coupled to the radio, and what radio did you try it with?
You need to determine the tuning range of the loop. You may need to add or
remove turns to work with the particular variable capacitor you have, to get
the loop to work throughout the BCB.
With the capacitor plates fully meshed (the low-frequency end of the tuning
range) slowly tune the radio until you notice the noise peak; you may need
to rotate the capacitor to make sure you're hearing the peak. The peak means
the loop is tuned to resonance with the loop winding and the variable
capacitor. Ideally the low frequency end will be at or below 530 kHz. Rotate
the cap so it's fully open, and find the upper tuning resonance
point--again, it should be at or above 1700 kHz. It's not likely that a
single cap and loop will cover the full 530-1700 kHz tuning range, though.
And the tuning peak is generally not as pronounced at the upper end as at
the lower end. If you're unable to find either the upper or lower end of the
tuning range, then start with the capacitor at half setting, find the peak,
then slowly work up and down from there. If you have no peak at all, then
something is wrong with the loop or the connection to the radio.
Keep in mind that the radio's automatic gain control (agc) will also tend to
even out a difference between a strong signal and a weak signal, in an
attempt to make them the same level. But tuning the loop to resonance should
always give a noticeable peak in the signal.
IRCA offers two items you should have--the paper "DXer's Technical Guide",
4th edition, 2004--available from Phil Bytheway's IRCA Bookstore; and the
complete list of IRCA Reprints on a CD, available from Lee Freshwater. The
Reprints CD has many loop articles on it; and the Tech Guide has a whopping
33 pages devoted to loops. If loops weren't useful, so many articles over
the years, and a number of very successful commercial loops wouldn't have
come about. Many people have successfully built their own loops--there's no
reason your loop can't end up as a successful project too.
Good luck, and please spend more time evaluating your new loop before giving
up on it.
Steve
-----Original Message-----
From: irca-bounces@hard-core-dx.com
[mailto:irca-bounces@hard-core-dx.com]On Behalf Of Ira Elbert New, III
Sent: Tuesday, June 21, 2005 8:17 AM
To: ABDX@topica.com; am@nrcdxas.org; irca@hard-core-dx.com;
dxlogs@mwcircle.org; am@am-dx.com
Subject: [IRCA] My Loop Antenna is complete...
and I am not very impressed. Here's the one I built from the DXer's
Toolbox...
First of all cut two pieces of 2 inch X 1 inch timber, each piece measuring
25 inches long. Half along each of these legs cut a piece out of the legs
exactly the size of the other leg, so that the two legs can be screwed
together in the form of an X. Then cut 4 pieces of timber 6 inches long,
these are screwed on the end of each leg to form feet, the primary wire
coil is also wound around these four feet.
Firmly fix in place one end of the 120 foot length of wire to the centre of
the frame, where the two legs cross, feed the wire to the end of one of the
legs, and wind it around the four feet for 18 turns, then feed the
remaining wire back to the centre of the frame using the same leg as where
the wire began, this is most important, both ends of the wire must go from
the winding coil to the frame centre along the same leg. Affix a tuning
capacitor salvaged from an old radio to the centre of the frame, where the
two legs cross, using glue or whatever, I use two small nails hammered
into the legs, so positioned to hold the tuning capacitor in place. Then
cut the wire ends to make a neat connection to the tags on the tuning
capacitor and solder the wires in place.
I used the VC sent to me by Mike Stonebridge and used 20 Guage wire.
I tried it last night after I finished it and while it does display a bit of
direction, the signal leaves a lot to be desired. Even local stations were
off by several dB's. I am going to go try it in the daytime in a few
minutes, but I thought I would post this. Any suggestions?
Ira Elbert New, III
Watkinsville, Georgia
"Proudly Serving You Since 1964!"