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Two K9AY loop system is super

By Al Merriman - K4GLU
July 4, 1998

The two loop system is up and running.
In a word, super!
There is no question that in many cases the front to back on the loops is superior to a pair of slopers and I've not run into any situation yet where it was worse.
During the day on some frequencies I'm able to choose between three different stations just by switching antennas and adjusting the termination.

As mentioned earlier to get full performance from these antennas a variable termination is required.
The Steve Byan Vactrol method works a treat. This is very easy to implement. All you need is the Vactrol installed in place of the terminating resistor, a 1K pot in the control box to supply power and an additional control line.
For my unit I'm using 5 conductor flat rotator cable. This is still sold by Radio Shack.
I'm using the updated control box, with added 1K pot that was described in the May 98 QST on page 73. This gives seperate lines for each relay, variable termination and leaves another unused for possible inclusion of a preamp later.
These antennas work very well as half of a 2 antenna phasing setup. I've tried them against my slopers and an MFJ-1024 Active Whip with a DL-2 Delay Line Phasing Unit and gotten excellent nulls.

More testing is going to be done including building a control/relay box that uses separate feedlines for each loop to see if these loops can't be phased against each other. Since they are mounted at 90 degrees to each other this should work. We will see.
That's about it.
For Medium Wave DXers this is an excellent project and I think I can guarantee you will enjoy it very much when you have it up and running.
SWL's - don't ignore the possibilities here. These antennas were originally designed for use on the 160 and 80 meter Ham Bands. You will have to make yours a bit smaller to cover the Tropical Bands.

My thanks go out to Gary Breed, K9AY for the original design and to Steve Byan for the variable termination. It's very nice to build a project and have it work as "advertised".
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