Topband: K9ay loop not performing
pa5mw at home.nl
pa5mw at home.nl
Sun Dec 8 05:36:11 EST 2019
Over some 20 years have setup some at least 15 K9AY's at about 10 different locations.
On some locations it worked better than others. There is always 15 dB F/B at minimum.
Top height, length of the loops, optimal balanced corner positions; never noticed anything critical. This thing is a superb starter RX antenna.
The max F/B I measured was 42dB, both measured with a Perseus SDR.
Above spec are achieved in my puny backyard where the K9AY's corners are close (as in 1 to 10ft)to either a metal fence, my shack(and alu windows) and the neighbors TV.
I use two 8ft copper ground rods. Have tried radials and chicken mesh on the floor additionally, but that did not help. Guess my type of soil is already good.
See pictures for the simple setup and F/B performance both on 160m and 1400 kHz at: flickr.com/photos/pa5mw/albums/72157688739777191
From: Topband <topband-bounces at contesting.com> On Behalf Of N4ZR
Sent: Saturday, December 07, 2019 22:14 PM
To: topband reflector <Topband at contesting.com>
Subject: Topband: K9ay loop not performing
I just put up a K9AY loop, using the Array Solutions control boxes, and am pretty disappointed. There is no audible or visible difference in the noise level, while the received signal strength is down whenever I A/B it with my inverted L. There does seem to be a little directivity, but not much, and subjectively I find that weak signals are all heard better on the transmit antenna. Judging by results in the current contest, I've got an alligator on my hands!
The preamp amplifies by a couple of S units, and I can hear the relays out at the antenna switching when I change directions or termination resistances, although gain and directivity do not change noticeably.
From this I assume there's nothing wrong with the electronics
I tried to do my installation "by the book." Ground is provided at the base of the antenna by a 6-foot ground rod. There are two common-mode chokes on the feedline, one at each end of approximately 100 feet of RG-6. About the only deviation from the published design is that the top of the crossed loops is at 28 feet, not 25, and the loops have their bases more or less horizontal, where the published designs show them tilting upward approximately 15-20 degrees from the center in each direction. I can make that happen with some more rigging, but before I do that, I'm looking for suggestions of other places to look for the problem.
73, Pete N4ZR
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