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I am thinking about making a compact and reasonably light MW ferrite antenna for use set up? outdoors on? portables. I am looking at the Stormwise ferrites which are in plastic sleeves and about 1 inch diameter. The shortest is over 6 inches long, and that would be a handy size. I may want one closer to the maximum length of the ferrite antenna in my radios which is 8 inches, but no longer than that to keep it handy. Plan to use it set up on a hill top? picnic table for a mini midday DXpedition.? Plan to put the cap in a plastic container or just use the PL-360,365 or GP-5/SSB which can tune a nearby loop. My other portables I'd use inductively with a cap are the Sangean PR-D4W and PR-D15 which are quite sensitive barefoot. I have made quite a few loops before. My question is about the Stormwise ferrite or something similar to use. I have 7.5 and 12 inch X 1/2 inch Amidon ferrites, but they seem too fragile to carry off to a picnic table, and a 2X16 inch ferrite toroid? stack which is much too heavy. I am trying to keep everything compact and light enough to carry in one trip from the car to a public picnic table in a bag. Anyone think of any other source for ferrite which is made durable?
-FARMERIK

Thanks John. So you don't think going from 1/2 inch diameter ferrite to 1 inch diameter would make much difference as far as 'sensitivity' or signal strength? - FARMERIK

Greetings folks, I'll put my tuppence worth in.? An inch thick ferrite would gain little and increase weight. A better idea would be a hollow inch ferrite, maybe similar returns with less weight. I have had some success butt glueing two 8inch ferrite rods together and reinforcing the join wrapping with note paper and araldite. A hollow ferrite rod could be? made, in a similar fashion, using a number of suitably sized ferrite beads. How would it do? Max vk2tti.?

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02 Jun 2018 23:50:50 +0000

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[loopantennas] Re: Compact ferrite loops for Portables?-FARMERIK


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Thanks John. So you don't think going from 1/2 inch diameter ferrite to 1 inch diameter would make much difference as far as 'sensitivity' or signal strength? - FARMERIK

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On my large 2.125 inch OD ferrite I wind coils on interchangeable forms for different purposes. Forms with an OD more than about 3 inches do not work as well.

I believe the TECSUN PL 360, 365 and GP-5/SSB all like pretty high uH to tune. I do get my Litz from your source, and also have the tuning caps he sells as Hi Q which would like a lower coil uH for MW. The interchangeable coil forms allow me to easily use the same ferrite. For outdoor temporary use, perhaps spraying with acrylic would help protect the Litz from moisture.

Recently I bought the portable version of the W6LVP broadband amplified loop which is interesting, mostly to set up outside on a remote hill top. It's only 2 feet in diameter, so reasonable to set up temporarily.

-FARMERIK

I am not much on understanding RF theory, but maybe you can explain why my 3 coil Litz sleeve for the 2 inch ferrite stack has an? extremely narrow pick up pattern. My best guess is the outer coils are out of phase and cancel the sides of the pick up pattern. Tuned with a cap, when I move a radio with a short ferrite inside it along the antenna, it nulls half way between windings on the big tuned loop, and makes an odd noise halfway between the coils. For such a huge set up, the signal strength is not that strong, but it allows me to choose two or three AM stations in different directions on some frequencies at night. It works weather I understand it or not.

I have the PK amplified and tuned AM loop, as well as the broadband Ham loop, and both pick up a narrow pattern off the rounded edges instead of the opening.? I hope to hear more than one AM station during the daytime at an RF quiet location. Unfortunately my radio room is above our kitchen and TV/cable box, so that pattern for a loop hears more house RFI from below. Same reason I doubt the Quantum loop would work well in my radio room with RFI below it.

I'll have to look up Palomar. I forgot about them.

-FARMERIK

My Sangean PR-D7 beats the better rated barefoot PR-D4W and PR-D 15 with a 20 inch PK passive loop so far. - FARMERIK

Greetings FARMERIK, I have, before me an antenna consisting of a 30inch length of plastic electrical conduit, inside? each end of the conduit a 9inch ferrite rod is secured. Over each rod a coil is wound over the conduit. The outboard end of each coil is is connected to the inboard end of the other. The tuning cap is connected in parallel? with the coils. I believe the coils abet each other. The setup has a broad reception angle an a very deep null. Perhaps, as you say, your coils are fighting each other and a reversal of the one of the coil connections may improve things.Regards vk2tti.

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05 Jun 2018 02:07:53 +0000

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[loopantennas] Re: Compact ferrite loops for Portables?-FARMERIK


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My Sangean PR-D7 beats the better rated barefoot PR-D4W and PR-D 15 with a 20 inch PK passive loop so far. - FARMERIK

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Farmerik, I'm really liking this new loopantenna group location. I noticed everything transferred including all files and pics.You can see my stacked toroid pics on page 3 of pics. It truly shines on VLF as does the FSL I must credit Everett Sharpe for their design and conception.He is also built some air loop masterpieces.
Some of my early loop pics are in the transferred files section. It was an ill conceived ploy to get better resolution. I'm glad they're still around. They were/are crude in comparison but fun to build and I learned a lot. That's what loop building's all about! ? ? ?