Ham Radio - Rebuilding my junk box magloop with wheelchair parts
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- Опубліковано 23 лип 2024
- Someone gave me round metal hoops, what else am I going to build? (ha!)
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Hit me up on the echolink repeater down by my house: W9TE (Node: 519521) - Наука та технологія
So much for getting anything done for the next 20 minutes! :)
Great video! Pi is an awesome number but for those who wish to avoid math with it can just measure the circumference of the outer loop and divide by 5 to get the length of the copper tubing for the inner loop. Keep up the good work Kevin!
That'll be old chief Ironside stranded then!
Thanks Kevin - you have a superb presentation style and you inspire others to try out stuff. Well done from the UK. 73 De M6JVI
Great video!!!! I found a bicycle Ring on dumpster and guess what came into my mind????? Yup!!! A magLoop!
I think I saw another video somewhere where someone had done exactly that.
Just goes to show - you can have fun on the bands with a little work and hand-made gubbins, even when the bands are as flat as a flounder.
Pi are square. No silly, pie are round. Cake are square!
You got up to Thunder Bay my home town!! very cool
Educational and entertaining. You get a big Michigan "Thumb's U.P." for that one... great video and very good use of imagination.
Outstanding video Kevin. You do such a nice job on these construction projects and the video production is excellent. You must have been a teacher in a previous life. If not, you would make a good one. Nice job!
73,
George
K2WO
Excellent video as always Kevin. It answer unasked questions and encourages experimentation and involvement, getting your “hands dirty”.
At least it does to me. Thank you !
73 de Juan KG4QYY
Great video Kevin, nice variable cap you had there.
It was a hamfest score. I think I paid $5 for it. There's always someone at a hamfest with a box of them. Keep an eye out at the next one you attend.
+John Kullman thought I mentioned in the vid. Approximately 15-700pf if memory serves.
Good stuff, by-the-way, that "magic number" 3.14....... is used throughout the Universe. Nice mechanical build
I am loving your presentations Kevin, I was afraid of the MLA until you explained it for me. Could my Kenwood ATU be used at the base for a main and fine tuner? Coax input takes left side of the horseshoe and then what would normally go to radio goes to right hand side of the horseshoe? Thanks VK8LLA
Awesome! That's about the same size as my bicycle wheel mag loop. I've been wondering about putting the other wheel alongside it as you did with the wheel grip rings. Do you think it would make much of a difference considering it's a small compromise antenna? And a friend noted the same thing about high SWR with his analyzer, but low with the built in SWR meter. I thought is was a bit backwards because higher output signal returns higher SWR readings. I'll mention it to him at the next Technet. 73 DE KG5KYJ
When you calculate the circumference or diameter of for example copper tubing for the outer loop and a heavy gauge wire for the inner loop, do you use the center of the material with disregard of the material thickness or do you calculate the outer surface circumference? By calculating a length of material without respect to material diameter, the measurement will be 'centerline circumference' which will differ a great deal from the outer surface circumference depending on material diameter / thickness.
I guess this might not be critical as long as you are consequent, keeping the relationship to as close to 1:5 as possible? 🤔
pi represents half a circlie in radians. or half a sinewave. 2 pi equals a full circle or a comlete sinwave.
Nice antenna very impressive and something I will try, the question is for 40m- 80m what diameter for loop?
Try using this one at the end. It's the one we are using around here, and gives you a lot more info from the few things you just type in. It really couldn't be any easier. www.66pacific.com/calculators/small-transmitting-loop-antenna-calculator.aspx
I was thinking for cheap vintage shortwave boombox RX or portables that have telescoping whip antenna and have get transistor front end. The 9 to 1 impedance match for coaxial cable. So I can be indoors and listen to RX dx. The 9 to 1 balun clipped onto the telliscoping whip and the battery negative post and the coax going out to a antenna preselector and outdoor loop antenna.
Probably no need to go to all that trouble. Many of those radios have a high impedance antenna connection on the back. Just a long piece of wire going out a window into a tree would do fine. Honestly, you could just clip the end of the wire onto the existing whip without extending it and get loads of signal.
I am going to try this. Why did you use both loops? Was it to lower the resistance or the cool factor? :)
Excellent, thank you and 73 de WA5SAT.
I like your mag loop work very much Kevin. 2 ?s . Are the 2 loops connected electrically , can one be used? and can they be insulated as a two turn loop to chance the band like the your larger loops did?
Howdy. No, the two loops are not connected electrically. They couple magnetically.
There are single loop designs, they work differently, may or may not be as efficient, and are usually broad banded.
Yes, multiple turns are possible to get lower in frequency, but efficiency goes way down and RF voltage across the capacitor increases to very high levels.
My issue is, where do I find a capacitor that is inexpensive. Still wondering what old machines would have a cap on them. Any suggestions?
Hamfests! There's always a guy with a box of them on his table at hamfests.
Can you see if a 9 to 1 could fitted on a cheap whip antenna.
Sure, but you'll still need a counterpoise. Or, if you're running QRP, and have a long semi straight coax run, the shield of the coax will do that job. Scan back in my vids for my cheap and simple field vertical. I did almost exactly that. About a 16 foot radiator gets you 20-15 meters pretty well.
Muy bueno, simple antena magnetic loop. 73" Kevin.
Where can buy all parts
Variable caps can be bought online on ebay or amazon. I get them from hamfests, there's always a guy with a box of them at those. The loops can be made out of copper pipe from the hardware store. But the point of this video was building a loop out of available junk. ;-)
Hi Kevin,
Thanks for another interesting video on loops. I'll have to keep my eye out for for the drunk old bums who park up outside the pubs round here with their wheelchairs. No only kidding. But the idea of keeping a watch out for an old one seems a good idea. I will have to get the calculator out as math aint my top science subject. That aint strictly true. ok on the math formula, but rubish on the arithmatics, ence the magical calculatore will sort that out. Wish they had been out when I was a kid. Here's looking out for another of your videos. 73 de John-aka- G0WXU.
Thanks Kevin for this representation, after I saw your video I remembred that I have wheel of bycicle fuonded in the street it is made from aluminum can I used it to build magnetic loop antenna? Thanks a lot and best 73 de KD5BKW.
I've heard of others using bike rims to make loops. What I've heard is that they work ok. Give it a shot. Just make sure you use heavy wire to make a good solid connection to the variable capacitor.
I don't understand how these antennas can work. Why is that coupling loop not a dead short?
At DC it is a dead short. However, once you move up in frequency, you reach a point where the outer loop is resonant and it magnetically presents a load to that small loop and the RF will couple to it. The same sort of thing that happens in a transformer. The energy will 'go' where it finds the best load.
It's similar to a the way a multi leg dipole works. If you have a dipole with two sets of wires, one set cut for 40 meters, and another set cut for 15 meters. When you apply RF at a 15 meter frequency, the RF will go to the legs that are resonant at that frequency.
pegbars It's weird Stuff RF nothing like dc..I recently bought a Duel band vertical for mobile work and when I metered the Coax plug it has a dead short lol goes against everything I have ever been taught about Antennas but guess what it works...I still cannot understand why or how tho..
Nice vid need to go dumster diving now
73
G0myd
The local Goodwill store had a used wheel chair for sale for $15. But I didn't get it (hopefully I won't need one). Then after I got home, I opened your video.
Moe k2jdm
+jdmeaux you know, the same thing happens to me, as soon as I throw something out that's junk, I come up with an idea that I need it for.
Ha! The same thing happened to me before I stopped throwing anything, other than household garbage.
Best Regards
73! Alexander R2FBT
@@loughkb j
My grandpa had a ham license for 11 meters.
He could use his rig back before it was citizen band.
Hi Kevin and viewers, there's a great website for working out the dimensions and capacitor needed and also a lot more information about the loop you want to build : WWW.66pacfic.com
73 clive