First off, Let me say that I like small magnetic loop antennas (magloops).
Most of my loops are light and quickly deployable; they can be set up and taken down outside depending on weather. The MFJ-1786 (and some other good magloops) are not so lithe and agile. They are not good "foul weather friends." Although the advertisements and instructions indicate that they may be used outdoors, there are such cautionary statements as "The black housing on the loop element has drain holes for moisture. Never seal the drain holes." and, "Sealing the bottom gap in the male coax fittings, outer shell, or the gap between the black housing and the connector on the loop, prevents condensation from draining out of the connectors and the loop housing."
In reviews about the MFJ-1786 (e.g. https://www.eham.net/reviews/view-product?id=174 ), one finds not only concerns about moisture, but also wasps and bugs. My own concern is increased by the fact that I don't have an attic and most of my house has aluminum siding (which may or may not hinder the magnetic component of radio waves). When I asked MFJ about whether they sell a protective covering, the response was,"Whatever you do, don't seal the black housing." Of course, that black housing is precisely where the motor and other vulnerable components reside.
My first recourse was to my local shoe repairer -- yes there are a few of them left. In addition to fixing the remaining non-disposable footwear, he also fixes luggage and sails. I described my need and, in response to my call, he said, "I think I could fix you up with a nice canvas cover for about $200.00. Of course during this lock-down, I can't predict how many weeks or months it might take."
I got an idea as I watched the lady next door putting covers on her lawn furniture. I turned to the source of all treasures: Amazon. Looking at lawn furniture covers, I saw a drum-shaped cover described as "Porch Shield Fire Pit Cover - Waterproof 600D Heavy Duty Round Patio Fire Bowl Cover Black - 40 inch" for $28.99, made from,"600D durable polyester fabric with an added water-resistant laminated undercoating." It comes in nine sizes with free delivery in two or three days for "Prime" customers.
In retrospect, I might have ordered the 36" size for a neater fit. Even so, it hangs nicely on the loop. There are tapes and Velcro strips that snug up the back. After a recent rainfall of three inches in 36 hours, I hurried out and felt inside. The black housing felt completely dry as did the interior of the cover. Certainly it is easier to put the cover on and off than to lug the entire antenna and stand inside for bad weather.

Figure 1. Magloop "Raincoat" in Place
On a whim, I decided to try operating the antenna with the cover in place. I was pleased to find that the tuning seems unchanged and I could make FT8 contacts on 30, 17, 15, and 12 meters. Clearly the real test would be multiple comparative observations of field strength while "doffing and donning" the cover at close intervals. However, I am an old man; and I have other foolish things to do before I accomplish that. Meanwhile, I hope that this little project may help other "loopies" like me to keep our equipment dry and comfortable.
73 and Good Health de W3UEC (Steve Dubin)
| KN6SU | 2020-11-24 | |
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| A Raincoat for My Magloop | ||
| My 20+ year old AEA Isoloop (the version with the wine barrel band type rather than the tubular radiator loop) has never been bothered by rain, though I have had to fix it for other problems. I figured the MFJ loop was similarly rainproof. | ||
| W3UEC | 2020-09-15 | |
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| Re: A Raincoat for My Magloop | ||
"I hope you don't have to operate your loop next to that stucco wall" Thanks for the kind words and advice. As you may see from the shadows bleeding through my lousy paint job, the wall is concrete block. VY 73 es good health de W3UEC (Steve) Reply to a comment by : AK5B on 2020-09-14 While the rain cover is a good idea I hope you don't have to operate your loop next to that stucco wall and air conditioner. STLs will couple to anything metallic nearby and are best operated 1-2 loop diameters above ground and in the clear (just like any other electromagnetic antenna; same principle in play). While I generally keep my smaller STLs indoors after use we are moving to a new QTH where I plan to keep 3 or 4 outdoors all the time---I think I'll be shopping for a few of those nifty covers soon! 73, Jeff, AJ5J The Loopy Guy in South Texas | ||
| AK5B | 2020-09-14 | |
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| A Raincoat for My Magloop | ||
| While the rain cover is a good idea I hope you don't have to operate your loop next to that stucco wall and air conditioner. STLs will couple to anything metallic nearby and are best operated 1-2 loop diameters above ground and in the clear (just like any other electromagnetic antenna; same principle in play). While I generally keep my smaller STLs indoors after use we are moving to a new QTH where I plan to keep 3 or 4 outdoors all the time---I think I'll be shopping for a few of those nifty covers soon! 73, Jeff, AJ5J The Loopy Guy in South Texas | ||
| W8LV | 2020-09-14 | |
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| A Raincoat for My Magloop | ||
| Wow this is a really Good Idea. It's so good in fact, that I'm surprised that the respective loop manufacturers haven't included a cover as an option. When it's really moist/humid, I wonder how easy it is to flash over the capacitors on the "non glass enclosed" ones? 73 DE W8LV BILL | ||
| KA0USE | 2020-09-13 | |
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| A Raincoat for My Magloop | ||
| how interesting, resourceful, and clever! | ||
| W4FID | 2020-09-13 | |
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| A Raincoat for My Magloop | ||
| This is a good idea. I have a W4OP/LNR loop for travel/RV use. It's a great antenna. I work lots of QSOs easily running 5 or 10 watts. But it's not at all wx tolerant. Cold (below about 50*) harms it. The mechanical parts of the remote tuner get stiff. Damp messes up the tuning and I worry about an arc over in the tuning components. Rain would maybe ruin it so I absolutely do not let it get rained on. I had an upholstery place sew me an "envelope" from a plastic tarp. Works well. Cost a ton. Wish I had thought about this approach! | ||
| DXACE1 | 2020-09-12 | |
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| A Raincoat for My Magloop | ||
| The Coverstore which can be found online is an excellent source for custom size covers. I had one made for a large chest freezer that we keep outside on our deck. They may also sell on Amazon. | ||