Re: Preliminary results -- W8TEE/AC8GY Mag Loop Testing

Terry Morris

Looks like a great job of pipe bending.

Terry - KB8AMZ
Brimfield Twp, OH USA EN91hd
Linux User# 412308, Ubuntu User# 34905, PCARS#78, NAQCC#6668, QRP-ARCI#8855, SKCC#14195

On Thu, May 30, 2019 at 4:54 PM Jack Purdum via Groups.Io <> wrote:

Conditions were not ideal, but we did get some RBN reports. While it's far too soon to say much, it appears the mag loop gives up about 1-2dB over the EFHW, which is up about 60' or so. VE8JY in Alberta heard us, but looking at their antenna system, they can probably still hear Jimmy Hoffa's last conversation. Also, we did get some rain during the test period which forced us to stop for a while. We tried to protect the cap, but were not totally successful. We are going to try again after we iron out some hiccups that showed up during the test. We also need to put it in a protective case.

About the design. The feed loop is rotatable (by hand right now), but we do not think it's worth the effort to motorize it. The software driving the cap via a stepper motor works pretty well, but we think we can refine it somewhat. We are about 50' away from the ML and the control aspects seem to work just fine. Why the 4-loop construction? Because we wanted to be able to fit the loop in the truck of a car without killing the efficiency. True, it's not an Alex loop, but we didn't intend it to be. On the other hand, it's going to be cheaper than most portable antennas and it can handle considerably more power than most. We have more tests in mind down the road, but we are encouraged by the results.

To all of you who tried to give us a listen today, Al and I very much appreciate your efforts on our behalf.

Jack, W8TEE

On Thursday, May 30, 2019, 1:18:40 PM EDT, Jack Purdum <jjpurdum@...> wrote:


Today we began testing Al's new mag loop (ML) design, shown here:

Inline image

It's a 40-30-20M "luggable" loop. It's about 3' in diameter, breaks down so it fits in a car, and we can get almost 1.1:1.0 on all three bands with our remote controller. (Peter Parker might use it on the beach down under, but most of us won't use it as a walkable antenna.) We ran some tests today and did see RBN reports so we know it radiates. However, it's not waterproof yet and the rains moved in...again. We plan on testing later today starting at 3PM EST on 7.050MHz. We will be transmitting on two antennas: 1) the ML and 2) an EFHW in an attempt to get some meaningful comparisons. We expect to run about 20W of power. We will alternate between the two, but you won't know which is which. After about 45 minutes and it the weather holds, we will move up to 14.080MHz to repeat the tests.

If you have time around then, use the RBN to report what you're hearing. We'd really appreciate it!

Jack, W8TEE

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