RADIO HABANA CUBA
The RJELoop1By KC2CAU
via Arnie Coro, host of "Dxers Unlimited"
KC2CAU's 2 meter MINI LOOP antenna
for Hand Held TransceiversHere is the plan for a 2 meter loop for hendhelds. It calls for a variable high voltage cap with about 22pf within its range of motion. You may have to use a stationary cap in parallel to adjust this. I have also enclosed a small program that does the calculations for any magnetic loop you could want. It even tells you what value capacitor to use!! It is freeware and I have used it for my experiments. It was written by a guy who is METRIC MINDED so you'll have no trouble with it.
Enjoy!!
Construction:
Note: This loop is extremely bi-directional with deep null if you look right through the hole. It will hit your local repeater but don't ask it for DX.
The aluminum covered base helps with take off angle but is NOT necessary. Due to your surroundings, you may have to do some tinkering to perfect the design. I have alot of pipes, and wires where I use my loops so they may tune a little different.
1. Cut a 31cm square of plywood or other flat wood for the base.
2. Cover the wodden base you just cut with either aluminum flashing or household kitchen foil (Instant Ground Plane). Get 15cm of copper tubing about 9mm diameter and form it into a circle.
4. Being creative, mount the loop about 8cm above the base in a vertical fashion.
5. With pliers flatten the two OPEN ENDS of the loop so you can drill and use little screws to attach the capacitor.
6. Attach the capacitor ACROSS THE OPEN ENDS.
7. Attach the SHIELD of a 50ohm coax, as short as possible at the exact opposite side of the loop from the capacitor. (6:00 position).
8. Attach the CENTER CONDUCTOR at the 4:00 position.
9. Run the coax out to an antenna analyzer or a tranceiver.Setup:
1. With VERY LOW POWER, give a 146mhz signal to the loop.
2. Tune the capacitor SLOWLY until a match is acheived. This design is looking for 22pf. You may have to add a stationary capacitor in PARALLEL to bring down the range of the variable cap.Usage:
1. Tune transceiver.
2. Open squelch all the way so you hear noise.
3. Use variable capacitor to peak the noise.
4. Check VSWR.
5. Operate!Click here to download the shareware program rjeloop1.exe
Havana, Cuba
03 October, 1998
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