I've been using a 1 turn "shielded" loop made from a large embroidery
hoop and 3M copper tape (Digikey). The loop is made from 1/4" copper
tape stuck to the outer surface of the inner section of the hoop. Then
ends of the loop are soldered to 2 short bits of #22 tinned wire at
right angles to the loop. I painted the hoop with Elmer's glue (who
else's glue would you use for a ham project?) and clamped on the outer
hoop.... The completed hoop is covered in 1" 3M copper tape with a gap
at the opposite side from the feed wires. After everything was solid, I
wrapped the loop in black electrical tape (Scotch 88) The feed wires are
stuck into a double banana plug. The Double banana plug sticks into the
The tuning section is in a Hammond 1590C box, it contains a 365 pF
broadcast tuning cap from Ocean State Electronics
http://www.oselectronics.com/ose_p96.htm soldered to a chunk of copper
clad FR-4 to insulate it from ground, and a plastic shaft extension.....
Signal is tapped off with a 10 turn to 2 turn transformer on a mix 43
1/2" core to a BNC on the side of the box. Balance to ground is
everything in making these loops work well! My loop tunes 9 to about 15
MHz with no extra C, and is easily "padded" down to 3.5 MHz with an
external cap stuck on the double banana connector. Bigger loops are
better for low freq.... I made a little one that works OK on 6 meters
This thing has been a hit. I've loaned it to several guys in the
club to run down noisy appliances, and power line problems. It has VERY
sharp notches. Listening to WWV on 10 and 15, I can easily tell you
bearing and arrival angle. With this loop and my FT-817 noise makers
have no place to hide!
Like most other things I build, I stole the idea from another ham
who posted it on his web site..... http://www.io.com/~n5fc/loop_ant.html
N5ESE did a cool job on his, but I think my matching box is better for
Dfing..... When I ran across this web site, I had to have one ;-)
Monty's loop looks better than mine, if you can't figure it out
from his write up, you're out of luck, he writes way better than I do.
73 DE WB7RSG
Gregory P. Daly
[mailto:firstname.lastname@example.org] On Behalf Of Jim Lux
Sent: Tuesday, January 25, 2005 9:23 AM
To: joe sloss; email@example.com
Subject: Re: [TowerTalk] DF Antenna
At 08:20 AM 1/25/2005, joe sloss wrote:
>This may be stretching "antennas" a bit but.... I'm in need of
>small "one-hand" carried portable antenna that can be used in the 3-4
>range to hunt down a persistent noise at my QTH. I'd prefer to use it
>with my Davco DR-30 rather than buy a small portable SW radio. Any
>Thanks, Joe k7mks
Since you want some directionality, and it's not for Tx, why not a tuned
loop? Wind a bunch of turns of some fairly small wire on a suitable
(a square a few feet on a side) and tune it with a 365pf cap.
The advantage of a loop in this situation is that it has a very sharp
(broadside to the loop), which makes DF'ing a bit easier.
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
any questions and ask for Sherman, W2FLA.
TowerTalk mailing list
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
TowerTalk mailing list