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Update on the mag-loop antenna

randall krippner
 

Now that I've had some experience using the Alpha mag-loop, I'm very impressed with it. I can generally tune it to nearly a perfect SWR by simply listening to the receiver and/or watching the S meter, without having to do a test transmission. If I take my time and listen/watch carefully to find the absolute peak in reception, I find I have the SWR around 1.5:1 or better. Someone mentioned that they don't work very well on 40 meters, but this one seems to be the exception to that. Works beautifully on 40, 30 and 20, which are the main bands I use. It can handle up to 100 watts SSB, 50 watts CW and 25 watts digital. I generally run 20 watts or less, usually 3 watts or less when it's on the 818. And the results have been much better than I expected. Even when I have it set up in the basement workshop about 5 feet under ground level it works beautifully on receive (at least as good as my OCFD and big vertical outdoor antennas). 

My Buckmaster OCFD came down in the last snowstorm we had (wire broke about 15 feet from one of the end insulators), and I haven't decided yet if I'm going to repair it or replace it. That antenna ran to the TS-990 in the office, and I've been too lazy to make up a new coax to run the vertical to the office. So the Alpha mag-loop is sitting on it's little tripod alongside my chair in the office, hooked to the TS-990 and the results from that have been embarrassingly good. Using FT8 (or JS8) at 15 watts PSK Reporter indicates I'm getting results almost as good as when I was using the OCFD running 75 watts.

Alpha makes a version of this antenna for permanent outdoor mounting with a remote tuner and I'm almost tempted to get one and forget about stringing up another dipole.

 

Nice report! Impressive that it’s getting out better in such a compromised situation. Newb question... are they very directional? Would I have to aim it like a yagi?

On Tue, Dec 3, 2019 at 5:41 AM, randall krippner <randallkrippner@...> wrote:
Now that I've had some experience using the Alpha mag-loop, I'm very impressed with it. I can generally tune it to nearly a perfect SWR by simply listening to the receiver and/or watching the S meter, without having to do a test transmission. If I take my time and listen/watch carefully to find the absolute peak in reception, I find I have the SWR around 1.5:1 or better. Someone mentioned that they don't work very well on 40 meters, but this one seems to be the exception to that. Works beautifully on 40, 30 and 20, which are the main bands I use. It can handle up to 100 watts SSB, 50 watts CW and 25 watts digital. I generally run 20 watts or less, usually 3 watts or less when it's on the 818. And the results have been much better than I expected. Even when I have it set up in the basement workshop about 5 feet under ground level it works beautifully on receive (at least as good as my OCFD and big vertical outdoor antennas). 

My Buckmaster OCFD came down in the last snowstorm we had (wire broke about 15 feet from one of the end insulators), and I haven't decided yet if I'm going to repair it or replace it. That antenna ran to the TS-990 in the office, and I've been too lazy to make up a new coax to run the vertical to the office. So the Alpha mag-loop is sitting on it's little tripod alongside my chair in the office, hooked to the TS-990 and the results from that have been embarrassingly good. Using FT8 (or JS8) at 15 watts PSK Reporter indicates I'm getting results almost as good as when I was using the OCFD running 75 watts.

Alpha makes a version of this antenna for permanent outdoor mounting with a remote tuner and I'm almost tempted to get one and forget about stringing up another dipole.


randall krippner
 

I'm told that they are directional, but personally I haven't really noticed it. When I rotate the antenna I see no difference in the S meter readings on receive. I suppose I should do some testing and see. Would be easy enough to check with PSK Reporter if there are changes in signal strength depending on orientation.

One thing I found interesting - I was told that this antenna can have problems with 40 meters, but that hasn't been the case in my situation. Works beautifully on 40 with an SWR of about 1.2:1 if I'm careful when tuning. On 20 meters, on the other hand, it does considerably worse. Best SWR I can get on 20 is about 1.7:1. Of course considering I'm running it in a room full of equipment, wires, electronics, etc just a few feet away from it, the environment almost certainly is having some kind of effect.

Of course JS8/FT8 is the only reason I'm getting out this well. I suspect the results would not be as impressive using SSB