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Magnetic Loop Test Number 2
Sep 7th, 2009 by kmack

The antenna restricted condo dweller (me) continues to look for a viable alternative to get on the air without having to go outside (think rain) and setup and tear down a portable antenna. I built a new frame for the magnetic loop and tried a few different styles of feed and resonating.

Ended the day with a 1.12 swr on 30m with this setup. I tried (fingers crossed) a dual section polyvaricon cap that I had on hand. It is mounted on a lexan square just below the gap on the mag loop at the top. After some time spent with an exciter loop, I decided to try the gamma match approach and regrouped. Using two stainless steel hose clamps to clamp the 12 guage solid copper wire I used for the gamma match. (actually the same wire I used for the exciter and 1/5 of the  10 ft. length of the tubing used) I cleaned up the copper tubing with a bit of fine grit sandpaper and tightened the braid to the main loop. Then I connected and soldered the center connector to the 24 in 12 guage wire for the gamma match. I drug the end of the gamma match and watched my antenna analyzer for a dip. Once I found the sweet spot, I cleaned up the copper tubing with sandpaper and clamped the wire while adjusting for best match. I then adjusted the distance of the gamma match wire from the loop and fine tuned for the lowest swr on the analyzer. After a good match, I put my Wilderness SST on the antenna and though the band was not loaded and had lots of QSB, I tried to answer a CQ from WB3YIP and getting no answer called CQ myself just to see if anyone would pounce on me! No contact yet, but at least the capacitor did not blow up yet! Sort of fun seeing what it will handle. More later as I get further along in the project. Thanks to CW-Code Warriors Yahoo Group for the help and encouragement they have offered.

Here is the 2nd iteration of the mag loop in my living room

Here is the 2nd iteration of the mag loop in my living room

The gamma match in test state

The gamma match in test state

The polyvaricon capacitor-- will it last or burn up from high voltage?

The polyvaricon capacitor-- will it last or burn up from high voltage?

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