Small Cheap Linear Loaded 80m Dipole
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- Опубликовано: 2 окт 2024
- The legs of this dipole are only 12.4m long (about 40 feet). See what you think. Callum.
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I actually might be able to fit this is my back yard! Excellent timing, sir!
Great!
using electric tape (and a piece of paper towel) is standard construction shop injury (bandage) repair. Been doing that myself for years. Right On, Tom!
AH!!
More serious cuts may require crazy glue.
😂haha emergency plaster for a while on your finger
WB4BKO Better to use a pair of scissors, or diagonal cutters to remove heat shrink tubing. Would I be presuming correctly that 300 ohm twin lead could be used for the dipole elements? I have acquired a large amount of it and I think it would keep the spacing fairly constant. Good video. It is quite obvious you are having a lot of fun doing these videos. I learn something from each one. Keep 'em comin'! 73 Norm Davis
Lot of fun.. Oh yes :)
Nice to see your videos still appearing during this "troubled time"!
Always!
I figured your finger was resonant at too high a frequency.. so you trimmed it!
Great video!!!
Linear loaded doublet for 160m like to see that Callum... Be better if you could design it for a 35 foot wide garden 😮
Haha.. Yes :)
Does the RF say: ah, this is the braid, I do not radiate on this! (?) In fact, this is a horizontal 1/4 radiator with L-shaped counterpoise. Either a good choke on the coax or a 1:1 UnUn is required.
I have talking coax. You should buy some :)
Dear Callum, thank you for ALL of your videos. My experience level in amateur radio is quite low, and/but I am an avid learner. My original idea (for an 80 meter inverted V dipole) was to cut two lengths of wire at 40 meters, connect them to a 1:1 balun, connect my coax, then raise it up about 16’ (5m +/-) and test SWR. You automatically use less wire than it seemed appropriate. Can you give a short lesson or explanation on WHY one would not use full length? (80meters). Please forgive what May seem a sad newbie question. Respectfully yours, from the west side of the Atlantic.
Firstly.. You are correct. For a linear loaded antenna (this one) we effectively added some inductance along the whole length (12m or so) which meant it needed to be less long. We could have also done the same with a coil somewhere along the length - to make the length smaller. But it's not a "forever" solution.. There comes a point where the SWR curve becomes a bit to narrow for day-to-day use. Your solution of course is frankly the best..
Glad to see some older videos
73 KQ4CD
Place marks on the floor foot half meter to measure wires.
Keep it up Cal! Hard to keep a good man down 👍
Always!
Question, the video description says the legs are 12.4m long but in the video I thought you said 14m long (before cutting the meter or so off to get it to resonance)?
The reason I ask is I want to do the same thing but scale it up for 160m. If the length of each leg was 14m then it looks like 26.52m per leg should work for 160m (roughly).
Thanks,
Dave
Dave.. I can't remember - however if you went 25m of linear loading each side, it'll be close. You will just need to faff about at the end with cutting the odd bit off..
When I make any antenna I make them shorter (2-3 ft.) and put 6 ft telescoping rods at the ends. I adjust the rods for proper length and when done replace the rods with wire. Works nicely.
Foremost, I would like to start by writing, I think I am going to be ill. The blood made me queasy. It will haunt my dreams for years to come. Secondly, I am but a mere hobbyist. I hold no radio license of any kind. But, I configure, assemble and repair many stations and equipment for many different services, including that of amateur radio operators. My question is, why not just cut two quarter wavelength cables, attaching one to the center conductor of a coaxial cable, and the other quarter wave length of cable soldered to the shielding and spread the two lengths of quarter wave cabling 180° from each other. Would this not accomplish a halfwave horizontal dipole?
Yes. That would work perfectly but I have come to realise many folks can't squeeze it in so this method cut the size down to around 2/3 (60% or so) without too much compromise.
Hi Callum, On the ARRL Antenna Book there is a Chapter about Dipoles and Monopoles. On chapter 2 there is a presentation of the Effects of Conductor Diameter and the K factor. I do not know if the DX 10 cable has a particular K factor that may be used to determine the length of the dipole? As an example they mention a dipole for 40 meter with cable AWG 12. The traditional formula will give 468/7.2 =65 feet. But given the correction of the K factor would be 66 feet 7 inches. They do as follows: 491.786/7.2 =ft X 12 in.ft/0.081in = 10.119. Then when you look on the table on the book that gives a K =0.974.
Finally 491.786/7.2=68.3, and 68.3 x 0.947 equals 66 feet 7 inches. I love to build antennas I'm not an expert at all, just sharing something that may shed light to the length challenge you had between 14m to 12.4m . Respectfully Jose David NP3JD
Experimentation seems to suggest we're running at about 93% on DX10.. But I might be wrong :)
Great video Cal/Tom, looking like you could use a small clip on tool pouch. I have one but I do the same most of the time, throw a tool or two in my pocket and go. LOL
Yes I got one (finally)! It's great..!
Hi Callum , Oyoun next video would put a link to you discord channel thank you
Good point! discord.io/dxcommander (we still have that!)
Thanks for posting this one to the new channel.. I knew you cared about me 🤣🤣 ...nice to see ya getting the Encyclopedia Commandica populated again
Haha Like the name!
Cal, do you make these linear loaded dipoles to order? I need one for 3680 +/- for /P but being in a small flat with no outside space I can’t make one myself.
Best wishes Andy / M0LSL
Yes you can! Just measure it on the floor :) Long tape measure! (no I don't make stuff for folks, only the doublet to order.. About £400).
Welcome back, Callum! I've subscribed again!
Legend!
Callum, if you were to use the same idea of the linear loaded 80m dipole, (ruclips.net/video/zWFU-VWOSJI/видео.html), is the same possible for 160m in a 160' (49m) foot print?
Yep!
Belatedly... another great video, Callum! it has given me an idea to 'squeeze' a bigger dipole into the space I have - an indoor one inside my garden shed (it's 24m long). Hopefully not too detuned by the steelwork.
Go for it!
Hey DXCommander!
I wanna have a QSO with you. When and where are you QRV?
Best wishes 73 de DL2MN
Always Friday at 12:00 London time
I just heard about the original channel. They should have told you what you did. Thanks to Ham Radio Dude for giving a heads up on his channel. Jack K5FIT
Great video as always but i'm confused. to me it looks like a folded dipole but I thought that you had to keep the radials a distance apart from each other on both legs. How does this work?
Oh heck.. It's just a dipole but the legs come back on themselves. Honestly, that's it.
How confusing. I don't get why they're cutting it at weird points. Why not just trim off at the very ends?
It's not confusing if you get the point we're making. But starting your comment with "How COnfusingW" makes me think you don't want to know so leave now :)
Electrical shop. Ask for a few Wago 221-2401 inline "lever nuts". These are used for connecting two wires. Perfect for adding some wire back to the end of the doubled back section. It won't hold the load of the wire from the end back to center insulator, but for tacking a piece back to the end it will work fine.
Could a full size 40 m dipole be added at same feed point to this linear loaded 80m dipole to make a fan without major interaction due to the 80 being linear loaded?
Actually, we did that :) I use it all the time.
That workbench is crying out for a ruler screwed to the edge. Much easier to measure out cable that way.
Haha yes :)
My wife measures to buy a yard of fabric from her thumb and forefinger holding the fabric, and the other end to her nose with her head at a specific angle which she has done since a teenager learning to sew. I challenged her once on this and she handed me a tape measure. It was right on. I can pour a teaspoon of salt in the palm of my cupped hand, and it will be right on, too. Meter and a half, huh? I trust you. And I have cut the wrong wire before.
Don't use your hand as a chopping board, when you have a lot of trees around you 😜
Indeed. Don't reach into the lava if you drop your keys in either...!
Oh, a welcome video. Don't know if it's a re-issue, but 80m has been bane of mine for ages for lack of space.
me too --- both 80m and 160m ! 73 de M5PM 🇬🇧
Hi cal. This is a very interesting ant which iam about to make, but for the cw portion of the band, whete formula tells me, each leg is around 20.3 m long in a normal dipole, and forgive my lack of calculations due to my illness, but if I take that 20.3 leg and simply do double it back on itself to 10.1m roughly in length, then trip for resonance, I should be in the ball park, or have I got that completely wrong.
Thanks for taking the time to read this. 73.
OK Brian.. If you want a SHORT version, then go with about 14m legs.. So 28m lengths doubled back. Then tune.
One of the EFHW antenna makers make a 75 ft. Luh loaded endfed and I plan on testing one. For years when living in a Condo I used a 60 ft. dipole w/tuner on 75 M phone and it worked better than I ever thought it would. You just have to be careful how it's installed and what's used to make it..
Linear loading Wasn’t the old slinky like that ?
No, I don't think so.. That's just "loading"..
' found a mile of 16AWG real silver coated copper single conductor insulated wire left over from building Vietnam era guided missiles, so the crew (me & garden rabbit #3) built an antenna out of it, of course. We cut this 80M Linear Dipole antenna last night, then strung & made it ring tonight shooting for 3.9 MHZ out here on the highly conductive Indian burial ground. We built it worse than you did, using my calibrated length of stride and Mk I Eyeball to measure, and it resonated first time at 3.880 without trimming at 1.37 SWR!!! (only 7 feet off the ground fed wifh 2 feet of old high loss RG58). Silver wire, yes, but your linear loading length estimates are sterling! The 15 dB loss showing on the Rig Expert raised our eyebrows; Sr. Rabbit blames the coax and low height. Hoping to make reliable 250 mile night NVIS contacts to Kansas City which is in first skip shadow zone.
Lovely!
Hi Callum! Absolutely love your videos! I haven't seen any modeling done on these folded dipoles in mmana-gal on your channel. Does mmana-gal accurately (close enough) model these folded dipole designs correctly? Woking on a shorty 40/80 Meters twin dipole for NIVS. Thanks and keep making this great content!
One enough.. You need to create more separation in software.
Funny
Wow you know your stuff.. I will share with all my ham friends .
I cut my finger nicely when I was using a new penknife for the first time... my sister didn't like the trail of blood I was obliviously leaving all over the floors of her Spanish villa..... And neither did the local hospital know English for "tetanus jab please" 😂 By the way, Callum: no balun? So you are going for a bit of co-ax radiation as well? 😊
I don't mind a bit of coax radiation on low-to-ground dipoles. Never did me any harm! (honestly..) VHF yagis and stuff is a totally different kettle..
When the elements were too long, how about just folding the ends back? You would have 3 wires running back and forward. Have you ever tried it? AC9YH --Roy
Er.. OK, I wonder if you watched the whole thing. Folding elements back certainly works but by HOW MUCH? That's the trick (and the math)
Ever tried this as a doublet?
No point because a doublet would have a tuner at the end of the balanced feeder.
Hello Callum I'm still new it's been a slow go for me. My question is how long should I make this antenna to get 3.855 - 3.916 here in the states.
Thanks 73s KI5OVM
Just like mine but cut it about 3 feet shorter.
I like this idea, but for my back yard because my 100 foot trees are along the edge of my woods some four hundred feet away with far shorter tall things much closer.
I have to give you guys credit for staying on tuning it. It paid off to be persistent for sure.
Yeah.. we got there in the end.. I am still using this today!
I wonder if I could add 80m to my 10/20/40 can dipole this way.
Yes.. You would need to trim / recalibrate some elements probably.
@@DXCommanderHQ I also could just use a tuner on the 40m element. I still have no real understanding of which approach is more or less efficient.
Does the folded section have less of an impact on efficiency because it is further down the wire length where the current is theoretically lower?
Would it have been easier to just cut ends and add a dab or solder? lol....and prevent cutting yourself...ha.. great video thanks....
Yes.
Why cut the antenna? Your impedence matcher should be able to get a match?
But for a portable situation, for a small group of freqs, tuning might be good.
Size.
I reckon that the point where the wire returns may be critical . If the phase of the current at that point is at 180 degrees then the returning wire current will oppose and cancel the field .
Tiny bit maybe but hardly noticable.
Love To See 80 Meters Live ANd Active !
Where is the spreadsheet you used to tune the antenna?
OK, search "m0mcx swr calculator" and your fav search engine will show it :)
@@DXCommanderHQ Thanks. I had found the spreadsheet for non-loaded dipoles, and was left scratching my head regarding the foldback cuts. The online version explains that very well. Will you be making a foldback version of the spreadsheet so we can take it into the field?
0n a learning curve here, but would that work on 80 as a "tri" linear loaded inverted v dipole abot 8.83 mtrs left and right total wire length 17.66mtrs ? say about 3.4 mtrs above the ground?
Erm.. I don't know. But you could try it and find out where the resonant point is. It will be sharp on the SWR curve..
@@DXCommanderHQ Ahh yes, hadn't thought of SWR curve. Has to be worth a shot. Sadly I spent my waking minutes this morning working out the build. 😂 Damn the antenna building bug!
Hi Callum, can you use a 1:1 balun on this linear loaded dipole?
Yes.. Certainly best practice to stop the feedline radiating.. I don't! Shh. Don't tell anyone!
If you add in a 4:1 balun, could this be used for 10m , 40m and 80m? Thanks, Dave KE8TTU
Well.. You could. Ideally with some decent coax and a tuner..
OK, Thanks for the reply@@DXCommanderHQ
You said something like "the lower this antenna is to the ground the shorter it can be". What is the cause of that effect? Is it a product of the linear loading or is it true of any inverted V?
Thank you for this video.
I believe (technically) it's capacitance to ground.
@@DXCommanderHQ seen. I have very poor ground here (limestone) but I'll give it a try.
Bloody antenna tuning 🤣🤣
Ive never seen anyone make a linear dipole with the wires on the legs touching like you have in this video. I’m so glad I’ve seen this because you’ve now got me thinking outside the box with antenna making. Keep up the good work.
Glad I could help!
So i can make a half wave 80m dipole and fold it back on it self
Yes.. But make it a wee bit longer, like 25m per side then trim to suit.
Great video, thank you for sharing ..
Thank YOU!
Thanks for sharing your video with linear loading. I could not comprehend however what you were cutting whether you were cutting 1 1/2 m off of one leg or 3/4 of a metre from both as I assume this is a wire folded in half 😮
Surely you got the idea.. Anyway, both.
@@DXCommanderHQ I'm still a little cloudy, but I think Cal meant 1.5 meters off each foldback leg and the total antenna length would remain the same.
@@stevesf28 Yeah.. every install will be a bit different..
Safe to assume this would work on 160m as well?
Yes John.
Would it matter it the leg wire was not insulated?
Not at all...!
More blood please! In living color!! ;-)
HAHA!
I would like to see two 4BTVs tuned alike oriented as a horizontal dipole I think it would make a nice muti band rotatable antenna on the cheap
Really nice vidéo, Do you think it's possible to use a ladder line in replacement of the wire ?
Yes BUT depending on length of ladder line, your match to 50 ohms will be guess-work so ideally go for a balanced tuner and ANY length of wire rather than coax.
I wanted to say, use the ladder line in replacement of the wire but keep coax feeding. Ladder line is perfectly linear. You solder the ladder line at the end to mimick the fold back wire and adjust the same way you do on the video. Not sure. Thank you for your video great youtube channel !!!
Does this need any type of balun or anything? Or does it just use coax the whole way to the rig?
Baku so or chokes are normally optional for HF.. I wouldn’t bother for this.
@@DXCommanderHQ much appreciated. I've been eager for 80m on my small lot and this may be the solution. Thank you!
Personally, I would probably use a balun... unless you want to couple yet more of your hard-earnt RF into the ground from the outside of the co-ax which is on the ground!.....Or possible risk of RF radiating off the co-ax near/in your shack and getting into your equipment-wiring and causing problems....
Do you have a link to that calculator?
No... Just multiple the wavelength by 0.17 and you shouldn't far off..
@@DXCommanderHQ So for a 20m dipole I am looking at roughly 3.4m per side or 6.8m total?
Thank you. But, blaming does not helping. For most newcomers is the missing part the most important part.
I'm not blaming anyone.. Don't know what you mean sorry., Say it in context next time. Thanks.
@@DXCommanderHQ You are saying that on 7:54 of the video. It's in the context dear OM
10:20 looks like you ended up taking a meter and a half of the whole length actually
So Call ignored the dx KE0NBK from Iowa 😉
Er.. OK
Thanks! 73 de YO8NIK
You're welcome!