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Magnetic Loop antenna build
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- Опубліковано 7 сер 2024
- In this video we build our own Man Portable Magnetic Loop Antenna. The video has details for two different antenna, both based on the Chameleon Magnetic Loop starter kit. Here are the details: a
- 40-10M single turn, man portable loop based on the Chameleon P-LOOP.
- 80, 60, 40M 2 Turn, Man Portable Magnetic Loop Antenna. Th
The 80,60,4m version can be built for only those bands, or as a convertible model with a switched capacitor allowing quick conversion between 40-10M or 80-40m modes.
Power handling: 10W DATA/CW or 25W SSB
A page has been setup with build notes, images, WSPR Test results, Links to buy the parts for your own loop, educational resources, calculators, and everything a Starter Kit builder could need to get their own loop build off the ground.The page is still work in progress, but will be completed within a few days after the video is published.
oh8stn.org/blog/2017/02/09/diy...
multi turn loop calculator: people.physics.anu.edu.au/~dxt...
Remember we are not trying to compare these magnetic loop antenna with full size amateur radio dipoles mounted many feet or meters in the air. Our goal is to build a practical and portable HF field antenna, which won't take lots of space, weight, which can be used with our QRP radio on the go. So the practical aspects of the loop may at times out weigh the performance benefits of other antenna designs.
I really encourage you to share your your own starter kit inspired homebrew projects. If you would like me to feature your magloop on the build page, just email me a full HD image to "magloop @ my callsign dot org".
- If you found this episode useful, consider dropping a buck in the tip-jar here: paypal.me/oh8stn/1USD
73
Julian #oh8stn
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This is a perfectly executed video!! BRAVO!! You're going in just enough details for the users to make their own.
A message for your subs:
One thing that is VERY important to mention is the fact that when manipulating, soldering or screwing nuts around the capacitor, it's PRIMORDIAL to protect the closed plates that create the capacitor as they're EXTREMELY fragile. NEVER install an opened capacitor because you'll break it!!!
Any crafting dust, gentile hit or the simple soldering flux particles falling on the plate might literally KILL the capacitor. The plates are about 0.020" from each other. Changing the distance between those plates might cause arcing a low power, shorts, high SWR at certain frequencies and reduce the overall performance of your loop. When you're done working on the loop for the day then place the tuning box face down on your desk to prevent stuff to get in.
It's important to underline that the capacitor that we're providing in the DIY KIT is the same that we're using in our CHA F-LOOP, P-LOOP and the incoming CHA P-LOOP 2.0 (us3.campaign-archive1.com/?u=e1cdcbe4da58e8277f75bd6b9&id=cdf412e790&e=[UNIQID])
Those variable air capacitors are US made and TOP quality. They aren't the ones that you see on Ebay or small online retailers! They're VERY expansive to manufacture. We've been able to offer them to you at a very reasonable price because of our purchasing power. We're buying them several hundreds at the time!
Cheers,
Carl Lavoie owner of Chameleon Antenna
Chameleon Antenna Thanks Carl. I added your recommendations and links to the webpage. I'll be adding other info and tools during this week.
Thanks for supporting the channel, my subs and your customers 👍
We all very much appreciate it!
de oh8stn
Is the second loop just hanging there no connections to the main or sub loops or cap? Thanks for the vid!
@@rosc7471 No. The LM-400 is a continuous piece. It is long enough that it needs to go around twice to use the length. Connectors on each end. So- one length of wire, two connectors.
Passed my technician test and received my call sign yesterday, thank you for the inspiration and videos.
Outstanding video.. This is exactly what is needed to get people interested in these types of antennas. Thank you.
Great video - I'm sorry I missed it when it came out. Thanks for sharing !
Bro, I frigg’n dig your channel. You do outstanding work. Keep up the great work
Excellent oportunity to learn antenna design and build techniques. Thanks.
+Tom Olofsson Thanks Tom. It's nice to get people interested and active, thanks for watching.
Well done video Julian. Great detail and good description. Thanks!
Thank you for the kindness and encouragement 👍
Really enjoy your videos. Thank you for your hard work.
Very much appreciate your build videos Nord...thank you.
Great job, focused and brief input!
Thank you Adam 👍
Julian, great job and i just got my kit from Carl a few days ago
Excellent: I live on a limited income and have saved several hundred dollars, thanks this was a fun project.
10:15 I would definitely short the conductors between the socket pin and shell rather than shorting the coax cable so that as soon as an open piece of coax cable is plugged in the shield is shorted to the center conductor. Otherwise one of these days I would grab the shorted piece of coax and try to use it as a patch cord somewhere and that would be very bad. At the very least a shorted piece of coax should have a warning label at each end to prevent it from being used as a patch cable.
Agreed. Next time I'll add orange heat shrink to differentiate them from one another
Great video! This was easy to follow.
+VideosByDPF Thanks, I was worried it might have been too basic.
I don't know the first thing about building antennas and you made it sound both doable and interesting!
I have not experimented with building loops in a while (been playing wire antenna).
I had started playing with 75ohm coax as the passive loop, I never finished the project.
It is worth nothing that OM0ET chose to use just the internal core of the coax on his loop. He said that doing this makes it less influenced by proximity capacitance (of the operator when tuning). On the flipside a lot of the high power loops use large diameter tube for the passive loop, which allegedly increases efficiency.
For the loop clips I'd be tempted to use plastic types, as the aluminium clips will each form a shorted-turn if tightened so that the ends touch.
geeeze, I have to wrap a blanket around me when I watch your videos....which are very interesting....
+nr3rful Wrap a blanket :) I don't make those kinds of videos yet 😁
Always good to see you in the comments 👍
Another great video. I just got the DIY kit from Chameleon. 4 questions if you please:
1. Is the length of the big loop measured from outer ends of the center pins of the PL-259s?
2. Is the length of the small aluminum loop measured from hole center to hole center?
3. Does the double loop you use for 80m and 40m work as well or better than the Chameleon Booster Kit which has a 146" long loop and 8" dia. small loop, and which uses the stock tuning capacitor (no shorting switch)?
4. Did you solder your Pl-259 connectors to the shield, or just twist them on and leave them? I always seem to have trouble getting the outer coax insulation jacket overheated when soldering on PL-259 connectors.
Thanks! KD4EO
Really great video. May I ask what exactly you are using for a supporting mast? It appears to be some kind of Selfie Stick, and am I right to assume it is non-conductive, made from kevlar perhaps ? Thanks de KM2U
in all the info that I have been looking at, and a couple of calculators that I have seen, I have not seen the size of the coupling loop in relationship to the main loop. what have I missed.. thanks Steve
I have been wanting to build a mag loop for some time. It is my understanding at this point that the large loop is in series with a variable capacitor, and the small loop is in series with the coax center conductor and the coax shield. Is this correct, or not?
Do you have a link to the switch you used? Im not sure which specs I need to look for?
I live in a condo in Florida and this antenna may be my only option. I have a question, how does this antenna operated if mounted horizontally. Does it radiate equally in all directions?
Nicely done Julian! Thanks for sharing. With your mod and remembering you operate QRP, what is the max power one can push into this unit?
Thanks Rob. I'm already thinking about the next build👍
Thanks for stopping by.
Hi +Rob Fern Remember this capacitor is exactly the same as installed on Chameleon F-Loop and P-Loop. Those models state 10W CW or 25W SSB. As I normally operate digital modes, I would also state 10w fit data modes with 100% duty cycle.
Hope this helps.
OH8STN excellent information here.
Great video as always. Two questions which one of the pre-built chameleon loops is the most portable if you wanted to do a SOTA? And the second question given that loop from Chameleon chosen from question #1 would you choose it over your MP1, ERB and MIL whip combo vertical? Again for something very portable as doing a SOTA as far as performance and portability?
The question really depends on the bands we want to operate. If we're talking about 20, 17, 15, 12, 10 meters, I would give equal weight to the chameleon "P-LOOP", MP1 and MPAS. on 30m, 40m, 60m, 80m we need more metal in the air. More wire or metal becomes heavy to carry up a mountain. So really it's an impossible question entirely dependent on how you want to operate. On 30-80m mp1 is lightest best performing option, but MPAS is easiest to deploy. If MPAS, MIL EXT is required on 40-80m for best performance.
Hi Julian I have a question about the support mast you are using. Can you tell me what it is made out of. Is it like a selfie stick non contuctive?
What's your video on mag loops. Actually several times. In one of your reviews you mentioned a chameleon starter kit. I'm having difficulty locating that do you know if they're still available somewhere? I'm not having any luck
Great video, i think i can do this without creating a disaster.
Question: I cant tell by looking at the video, but is both sections of the rotor plates connected with a jumper? I know that both the stationary plate sections are connected to the capacitor frame and one end of the loop. Tnx es 73, n5eqy Texas
+Walter Perry hello mr. Perry. I've answered that question and added a couple of photos in the build notes. You can find those notes right here oh8stn.org/blog/2017/02/09/diy-man-portable-magnetic-loop-antenna/ there's also much more information there which is useful for the Builder. Actually I think I'm going to build another one, using one larger Loop rather than the smaller double Loop, but that's a discussion for another day.
And me again if the bills notes don't give you the right information with the information you need and I'll add a more detailed section on this topic.
Julian
Kits are not available any longer for building your own. Where can you find a suitable replacement?
Great project. Please, could you provide information about the air capacitor?, where did you buy it?, what brand/model is?, faraday value range? Thanks EC7AJW, 73
Just discovered your videos. Great stuff. Wish I could turn the music off though.
I'm trying to find the right balance with the music. I've done a few tests with different types of music at different levels. When there is no music people stop watching the video much earlier (which is crazy). With music, watch times have almost doubled. My latest experiment is very light chill-out music in the background, with a less rushed voice over.
Anyway I appreciate the honesty and feedback.
OH8STN ya chill music sounds like a great idea. interesting to hear how much it affects view times! I wish UA-cam just had a music mute option. PS- I hope the chill music works but could not blame you if you have to use the rock music or whatever to keep the viewers watching. 73.
Clifford Novey thanks. I'll definitely stick with the chill-out vibe. I want to keep people watching because they're interested not because I tricked them with the perception of time.
Time to get editing.
Have a nice one.
Hi Julian - Thanks for your video series on the DIY Mag Loop antenna. I've watched your video a few times and I have a few questions. I hope you don't mind.
Q: You say, referring to the second loop, that "You'll have to adjust for the enclosure that you use" what does that mean?
Q: Is the second loop's center conductor and shielding shorted together like the first loop?
Q: You say "That measurement also includes the connectors and the barrel connector used to connect it to the first turn." However, in the photos, it looks like the two loops are not connected together - am I missing something?
Q: Do you switch out the longer 105.11 inch LMR400 when you switch bands to the 80/60/40m configuration? In the photos it looks like a longer loop is connected to the capacitor and the shorter one is simply connected to itself using a barrel connector.
Thanks for your help.
73,
+Robert Cox hi Robert. Great questions. I'll answer sequentially.
Enclosure: this only means if you have a very wide enclosure you should have just the length of the cable to account for the width of the enclosure. It's so small though I don't think that it will make much of a difference. It's just a few centimeters inches.
Coax shorting: the coax is shorted on both the main Loop cable, and the double Loop cable.
Connectors: Of course the two main loop cables are connected together in double loop configuration. Sometimes we make things too complicated in our heads. Anyway that comment refers to the measurement of the length of the conductor tip-to-tip which includes the barrel connectors.
Switching out longer lmr400,: I'm not sure if I understand. There are two configurations. 40 meters through 10 meters is the shorter lmr400 coax. Then there is the double Loop configuration which includes the shorter lmr400 coax and the longer LMR 400 coax connected in series. Naturally on 40 meters we can use either configuration.
I'll add more photos and clarification to the help website in the description sometime in the coming week
I hope this helps
73 de oh8stn
Julian - Thanks for your reply and for your additional information. I look forward to your other videos and I will look for the additional photos and clarification on your website.
Best to you and thanks for the videos.
-Rob
I really enjoyed the video, finding it very informative. I was looking forward to reading the write-up, but all I can see is the image of the kit... nothing else :( de K4DFH
How would this mag loop handle the heat and sun in the sonoran desert summers? I'm looking at these for a base antenna for my shack.
That entirely depends on how you build it. You can substitute the materials I used, for materials which are more suited for your environment. If I were still living down in Yuma, I would build it much differently than for portable Ops up here at 65 degrees north.
Hi Julian, Quick question: What is the maximum power in watts that can be input into this antenna? Forgive me if you mentioned it in the video and I missed it. My radio's minimum output is 5 watts and I don't want to start a welding project within the capacitor housing.
Did you read the build notes?
Are the measurements for the main and coupling loop measured tip to tip of the connectors after their installed? BOB AF2DX
Yes they are
Better to short the SO239 in the box, so you don't end up with a cable that could cook your radio if you accidentally used it as a patch lead...
Yep agreed. I do use different type of cable for patch leads so it's not possible for me. It's excellent advice for other people using the same style of the same look of cable. Thanks for the tip 👍👍👍
I will using lmr600 when I build my legal limit loop. using a beer bottle cap rated for 50,000+ volts in conjuction with an high capacitance air variable cap.
+kf4dcy Wow! How portable is that going to be?
OH8STN answer. Not very at all.
OH8STN ok, as for portability. not so much, wile I walk around with it. but I can carry it to a location then set it up. that is my kind of portability, as far as how I'll use it. being I'm on crutches for the rest of my life, after being ran over by a ford 3000 farm tractor and john deere tiller, laying me up for two months and five days in a hospital. how I get all of it to that location, will be in a wagon tied to me. super saturated salt water in a container, oil in a container, wire jumpers for the bottle array, all stowed inside the plastic pail the capacitor will be assembled in. as far as i know, the variable cap is only good for 100 or slightly more watts in a mag loop antenna configuration. its a cap pulled from an old Denton supertuner transmatch good for 5pf to 400 or 450pf. the tesla cap being for extra voltage capacity to reduce arcing witin the variable cap. seeing how caps are used as spark absorbers, without having to go buy a vacuum variable. but a vacuum variables caps aren't as damaged when it does arc. that's why I suggest adding this tesla cap built like a power line transformer. does this explain my logic better? if this works. I could add one or two more tesla caps so I can utilize the full capacity of the converted Dave made 16 transistor amp. letting me release the 4500watts pep the amp is capable of providing. when and if the world become without law. kinda like sweden and france. thats when I will use it that way. or in times of emergency. but isn't a world without law a world emergency? a greater threat than global climate change.
Hi this link is bad Love your antenna looking to build one could I use a gear reduced motor for remote tuning ?
chameleonantenna.com/ACCESSORIES/ACCESSORIES.html
@@Frisky0563 The link is bad....
Hi Julian! Very good video! I want to ask you where can i buy this small pickup loop conector? I need one. Or can you sell me one? Tnx Paul
Hi Paul I get those connectors from Amazon. You can find them for CB radio antennas.
OH8STN what i have to type in to websearch please? thanks
I'm a little busy now but I'll send you a link later todsy
Here you go
www.amazon.com/SO-239-THREADED-ANTENNA-MOUNT-ADAPTER/dp/B00LND0M92
OH8STN thank you very much!
There is some data that suggests a squashed feed loop rather than a round one provides for a bit more efficiency and bandwidth
That's not data, it's marketing from Alpha Antenna. They're trying to justify the benefit of not having a center pole support for their Loop. After extensive testing with a similar diy loop, I found that the squashing reduces SWR, giving the appearance of wider bandwidth. Unfortunately it does so at the loss of efficiency. This is most apparent 30m and below. The squashing also helps if you don't have a possibility of adjusting the distance between the driven Loop, and the Outer Loop.
Wasn't looking to dump on Alpha, just curious to understand why they were promoting this methodology. Every other loop on the market is symmetrical.
@@OH8STN didn't come from Alpha - came from my own experiments and looking up the various experiments that other operators have documented on the ways they feed their loops. I have also made 30/40 loops over the last 35 years - there are a multitude of ways to feed a loop (essentially an output tank circuit in valve terms). The shape of the feed is less important than its alignment to the plane of the main loop. Personally I prefer a transformer feed 73
Tnx fir this nice video. 73 de KB9K
What do you use for a stand for the mag loop?
HD camera tripod or ground spike
Saudações !!! 👍👍👍 TKS & 73 !!!
How do I wire up the Variable Capacitor wiring ?
All the instructions are in the episode notes. You can find those in the description
Tnx OM best 73s from a71br
Does the thickness and the width of the pickup loop matter. If so what are those dimensions?
I've experimented with various widths, getting various results. My best result was with the Aluminum bar stock, but RG-213 worked almost as well. The bar stock is 2.5cm wide.
So 2.5 cm wide or .984 inchs. What abut the thickness of the bar stock. Does that matter? Oh and thanks for the reply.
I'm sure the thickness has some relevance, but nothing I could detect in my testing.
So do you know how thick the T6 aluminum stock was that you used?
Thank you from CM99ld
I'm a bit confused. Is the second loop connected to just itself and not the capacitor. If so how does tuning happen on the second loop?
Also is your telescopic support metal. It looks like it is. Does this affect the antenna? I purchased the kit and I already have some extra lmr400 around. Just need a box for the cap and support. Gonna grab some stuff in town tomorrow. Thanks.
-KN4CUH
PS. I'm building a uBitx with a raspberry pi and 7" display all mounted in a pelican style waterproof case to digital modes. Planing on uses this antenna for.
Hi Steven the second Loop is connected to the end of the first Loop, looped around and comes back to connect to the tuning box. It's all in the episode notes. The link is in the description. I hope this helps 👍
so this antenna would not be for a 2m or 70cm outfit... like my Icom 5100 ?
im trying to find the best, antenna i can find to build myself, im trying to reach the nearest repeater, which is 31 miles away..... any suggestions?
Hammer USN Will of you're into loops, why not try to build a Hello antenna for 2m/70cm? Here's one idea for you. ua-cam.com/video/cu-Qq4RptS4/v-deo.html I would not put that on top of a car like he did, but the antenna design is one which I like very much.
Hammer USN Will of you're into loops, why not try to build a Halo antenna for 2m/70cm? Here's one idea for you. ua-cam.com/video/cu-Qq4RptS4/v-deo.html I would not put that on top of a car like he did, but the antenna design is one which I like very much.
Very good videos. have subscribed to the channel, 73 de Michael DO9YY
What are the savings from mounted to a kit.?
Can you elaborate?
@@OH8STN OK. The antennas come already assembled and ready to use, except set up. Now, buying the kit, such as the starter kit, then the ring, etc, will that brings any savings to the buyer?
A really excellent video with only one criticism. I absolutely HATE the music. Why is it that so many really good instructional videos are almost ruined by loud distracting heavy guitar music. I've seen this trend used on reality TV and it is the same, just plain distracting. If you really must add music to your videos, might I suggest using a very soft Jazz track. Other than this, I really enjoyed and appreciated the video. de KM2U
Great video BUT a wind protected/noise cancelling microphone would go a long way in keeping your followers from being driven crazy. Just sayin.
Agreed. That's an old video and just a couple of weeks ago, I updated the microphone
Hackadat picked up the video and blog. :)
hackaday.com/2017/02/25/loop-antenna-is-portable/
I had to tune out, the voice far to irritating.
annoying music :-((
Yes. Great presentation but the music and intense voice is to much. Think ham radio Bob Ross not Hulk Hogan. Love the content though.