HAM RADIO: Double Copper Loop for 80M Build

[@electronics.unmessed]

Just joined. Nice construction and great craftsmanship! 👍👍👍

[@johnnorth9355]

Viewer Notice - No kitchen worktops were harmed (much) in the making of this video LOL . Great stuff Mike and food for thought.

[@mike-M0MSN]

You got that right!

[@stevemorse5052]

Viewer Notice #2 The bandaid's (plasters) make a nice addition to the video! Great video

[@webmastercaribou7570]

If you run hot water through it it may make a nice hot water heater. Very nice design.

[@PerkinrBR549]

Awesome

[@boxingday11]

Well done Mike, thanks.👍🇬🇧❤️

[@mike-M0MSN]

Thanks 👍

[@Keith_WB2VUO]

Mike: I made a 2-turn loop a bit larger than yours, using RG-11/U coax for the loops. 51.5" diameter, supported on a PVC cross frame. Tuned with a receiver cap, 20pf - 400pf per section and series-connected for a 10pf - 200pf tuning range. I can tune it up from 3.2 MHz to 8 Mhz. Spacing is 2" between turns. This was a first build for a multi-turn loop. I plan to clean it up, and I like your spacers. I plan to cut a set for my loop but I need to remount the capacitor so I can cross the loops over at the bottom like yours. The price of copper shot through the roof in the last couple of years. If I went with copper tubing and fittings, at the current pricing, (March 2023), it would run around $175 USD just for the copper parts! My surplus reel of RG-11/U cost less than a single 10' length of 1/2" copper tube, and the reel end I bought has at least 300' on it. That's a lot of loops, no? Three loops here now, a walkabout loop made from an aluminium bicycle wheel rim (17 meters - 6 meters), a 36" single-turn loop (40 meters - 10 meters) and the 51.5" 2-turn loop (80 meters - 40 meters). I demonstrated the 2- turn loop on 80 meters from inside the club meeting room earlier and, running 5 watts on FT-8, made a contact some 275 miles away. That made believers out of the guys and gals at the meeting! Keep up the great work and posts. I need to build a cap like yours so I can run a bit more power, hi! 73, Keith, WB2VUO here near Buffalo, NY

[@johnwest7993]

I like to PVC and ties idea. BTW, you can lower the loop RF resistance a bit by sanding off the lead that is exposed at the fittings, since the RF follows the surface. I don't know if it will be noticeable, but it is a fact.

[@jasonhowell5362]

superb build

[@mike-M0MSN]

Thanks!

[@LincolnshireRose]

I have been considering making a simple single loop for 160M for a while now but you have given me an idea to double it up, maybe even going for a double loop with a smaller loop underneath, aka figure 8 loop. Thanks very much Mike. 88 and good dx de M1EBN

[@mike-M0MSN]

Go for it!

[@pd9rd]

Wonderful craftsmanship Mike, A joy to watch and learn from! 73

[@mike-M0MSN]

Thanks

[@Supernumerary]

The resistance of a mag loop is a very important parameter. Ideally the joints should be TIG welded, instead of soldered. Note that the lower the resistance, the higher is the Q, but the trade off is that high Q decreases bandwidth. A loop could have a very high Q and not have sufficient bandwidth for a SSB signal.

[@mike-M0MSN]

True

[@kevinmithnick9993]

Wait, Tig welding copper? I'd love to see that...

[@kevinmithnick9993]

Instead what about brazing with silver rod?

[@hamandshortwaveradioirelan4773]

Nice series of mag loop experiments, thanks for sharing

[@mike-M0MSN]

You are welcome.

[@ianxfs]

Seems to work a treat Mike. I like the spacer idea 👍🏻 A round file on the ends might sit them more snug?...or may be just extra faff for nowt! My garage floor is exactly the same as yours! Curse that grey paint! 😁

[@mike-M0MSN]

Good tip! and yes time to re-paint it.....

[@normandomarcolongo7438]

Lower your MIC gain/processor output 'cause the ALC is screamin'! BTW, the loop is gorgeous!

[@mike-M0MSN]

yes ALC, keep forgetting to adjust. many thanks

[@George10767]

Mike, in my opinion the results from a *twin loop* antenna are likely to be much inferior to those from a single loop. This is because the antenna depends upon the existance of a *VOLTAGE STANDING WAVE* around the loop. (This is where the principal emulates that of a half-wave centre-fed dipole). But with a twin loop design, the voltage standing wave in *EACH* of the loops is likely to be greatly distorted by the proximity of its twin.

[@tekspeditionplanet9109]

Very nice build. What is the pf span and voltage rating of the variable capacitor? Are you pushing a full 100 watts?

[@chrisgladman6851]

Nice ! A double it is then ! I see you discovered Alvin in Ashtead lol !

[@mike-M0MSN]

Yeah I did

[@chrisgladman6851]

@@mike-M0MSN lol !

[@g0fvt]

Has been decades since I last worked Alvin, he was G6DTW in those days. Loop seems to work well, interesting project.

[@Joe-KN4IFI]

Great loop Mike. Lets go for a big one, say 6 loops :). I just bought some stock futures in copper and you are going to make me money LOL. 73 Joe

[@mike-M0MSN]

Thanks 👍 lol

[@grandpaandlucas7054]

only working well when you hit Australia with 9+++ . nice to see a comparison with a dipole. where did you get the cap

[@krisraps]

Woow! That Ziptie Tube Insulator Trick I Will Write In My Book :)

[@stewartrv]

Ahh didn't realise you were a Devon lad, that's you Callum (& me too!).

[@mike-M0MSN]

lol

[@abdula4256]

Thank you Mike

[@63snampook]

.....and during TX, your ALC totally went bananas........watch out for that! NOT good (de PC7H) Cheers.

[@krisraps]

What A Great Antenna You Built. :)

[@mike-M0MSN]

Many thanks!

[@alzeNL]

fab work - it looks and is a professional build ! i dont fully undestand how it works but will research some more - amazing its getting out so well on 80.

[@mike-M0MSN]

It is awesome, thank you!

[@m0zeh]

Alvin lives up the road from me :)

[@richardve6pco163]

Hi Mike, very nice build. Wondering if you would get good results using a trombone capacitor instead of the air capacitor? 73

[@coccodrillo4you]

Hi Mike, Thank you very much for your very good comments on building your twin loop. Can you please tell me what value (pF) the "C" you installed has and also the diameter of the twin loop please. Thank you for the great inspiration. 73, Ingo

[@mike-M0MSN]

the range is 10 to 350 pF on this Cap.....the diameter is 1.2M (1200mm) x 2 as it is a twin

[@terrycody9986]

So Nice 💘💘💘💘💘💘

[@mike-M0MSN]

Thanks

[@dennisjoiner3717]

I'll give a look at your website, but do you have a build video or plans on the capacitor. Hind site being 20/20 I had a vacuum capacitor that was in a homebrew tuner. But sadly 20 years ago I had no idea what a Magnetic Loop was let alone wanting to build one. I'm planning on starting with a single turn, but love that two turn design you built to work 80 meters. Great video!

[@stufoster5862]

Hello Mike. Great video....I guess you are just up the road....I'm in Gloucester too. 73 de Stu G7WAY

[@mike-M0MSN]

Quedgeley Stu.

[@stufoster5862]

Ah, I'm just off Oxtalls Lane here Mike.

[@o00scorpion00o]

I've been reading that double loops are only more efficient if connected in parallel and not in series ?

[@ReedAB8AS]

Impressive!

[@mike-M0MSN]

thank you.

[@jeanlouisberthault7603]

Very nice job, could you describe your air spaces capacitor please? Congratulations from France

[@mike-M0MSN]

Making a video soon. 👍🏻

[@mahargkp]

Hi Mike...Great workmanship and I've fully enjoyed your video....would love to give it a go ..Will have to watch again for the lengths....My question is where did you get your capacitor from...This seems to be the big issue tracking them down....Thanks for any info and your time....Graham... m1bsz

[@mike-M0MSN]

Thanks 👍 you are right the Caps are very hard to find, I am going to build one soon,

[@mahargkp]

@@mike-M0MSN Hi Mike...Thankyou for replying...I think building your own seems to be the way to go...Will have to research that but it doesn't look easy or cheep to build....Thankyou for your time...

[@jasonhowell5362]

im impressed i remember when i built mine for 80 and 40m wish id of kept it but i still have air cap and motor perhaps you could build me a double loop lol

[@mike-M0MSN]

You gotta do it....

[@jasonhowell5362]

@@mike-M0MSN wish i could its finding the time besides you got the workshop lol

[@ZL1BQDRoly]

Your Hardware must love your visits !! Is there enough copper left in the UK now? cheers

[@mike-M0MSN]

I will need to mine the ore myself soon....

[@nlo114]

10:30 - I recognise Patrick's voice anywhere!

[@Justin-bd2dg]

They make a, "zip tie tightening tool" but I've just used needle nose pliers for the last 30 years without issue.

[@mike-M0MSN]

yep me too.

[@rajeshhuddar3470]

Have made a similar antenna, but a square loop. Get 1.1 SWR for 40m but not able to get 20m. The total length of the copper pipe is 24feet. Seeking your inputs to get 10m Thanks in advance 73.

[@mike-M0MSN]

Very nice!, the loop need to be 10% of the operating frequency, see www.66pacific.com/calculators/small-transmitting-loop-antenna-calculator.aspx

[@kevhaworth5313]

Mike. I' m in the process of building a 5M Circumference single loop for 60/40/30, it will be (eventually) brought to resonance with a variable vacuum cap. Please, how did the spacing of your double loop arrive at 10cm, are there formulas for this? Like you, I'll be 22mm and looking to build the double for 80m. I just can't get over the price of copper and fittings at the moment! ATB Kev, M0TNX

[@glenmartin2437]

Thank you. N0QFT

[@lyndarlehane582]

I too will build one. Can you say the value range of the capacitor, please Mike? And which one, where from. I like the integrated motor. Is a vacuum one unnecessary ? What transmitter power are you using? What can that capacitor take ? So many questions, sorry. But lots of us may want to copy this, and to do so we need to know a bit more.

[@mike-M0MSN]

you may get a lot of your answers in the next video!

[@markg6jvy135]

👍👏👏

[@solidol_workshop]

🤔👍🏻🔥

[@philtuckerm0dpk212]

Hi Mike, great antenna. Well done. Is there a drawing or website you recommend to read any more about it ?

[@mike-M0MSN]

In the description but not found any thing on twin loops!

[@philtuckerm0dpk212]

@@mike-M0MSN Thank you.

[@32_bits]

Hi Mike, new to your channel and enjoying your videos. Have you tried shaping the smaller pickup loop to closely track the curvature of the larger loop to provide max coupling? I made a coupling loop like this which formed a half Moon shape, the greater efficiency and lower SWR was very noticeable. You might also want to try soldering thick connecting copper wires direct to the cap terminals and then soldering to the main main loop to further reduce loop resistance. I plan to make a tubular capacitor as per one of your recent videos to add extra capacitance to my variable cap, but wonder if you have found a simple way to switch this in and out of circuit with minimum resistance contacts? And for your double loop how do you calc the distance or gap between the loops and could triple loop provide even lower frequency range?

[@mike-M0MSN]

Thanks will have to give that a try.

[@PhilG0BVD]

Ouch no kneeling pad you will pay for that later

[@marcusm6xpb774]

Mike are you banging your ALC way out the recommended boundary, looks like it is peaking well into the red

[@mike-M0MSN]

Yes, strange thing is the more I turn in down the more the radio compensates and turns it up ????

[@marcusm6xpb774]

@@mike-M0MSN that is strange, I guess you are adjusting with the mic gain as I don't think there is any other way to adjust ALC. Do you run the processor on or off?

[@NICKGAR7]

@@mike-M0MSN HNY Mike... on most radios, turning the power down puts the ALC up. Always check ALC after power changes.

[@Tump2010]

Does a loop work better higher in the air like a dipole would or do they work better lower to the ground like you have it?

[@mike-M0MSN]

I don't know.. I have only ever used mine at ground/3m high.

[@ON8EI]

Great job as per usual. I might have missed it Mike but what was your power? If you post a time and freq sometime I'd love to give you a report. de ON8EI John. 73's

[@mike-M0MSN]

A round 70 Watts for that copy.. :)

[@nicholastriantafyllou575]

Hi - Amazing results with the mag loop Mike. Do you use a separate receive antenna as the waterfall on receive is very even across 100Khz when I would have expected there to be a very narrow peak even on receive. Thanks - Nicholas 2E0GKG

[@mike-M0MSN]

No, same antenna, without the pre-amp there is a visible peak, but my camera is not able to see it...

[@carlossilva.k2wc.542]

Hey Mike Great Job one more time, quick question, What is the capacity range of the variable capacitor you are using? 73 de K2WC

[@mike-M0MSN]

In this build it was 10uH to 350uH

[@rajeshhuddar3470]

Good Evening Mike. Wish to make a similar loop. What is the total length of the copper tubing across both the loops. What should be the diameter of the inner loop. Thanks, VU3RHU, Mumbai.

[@mike-M0MSN]

8 metres of copper pipe, inner loop is 80cm.

[@rajeshhuddar3470]

Have made a parallel loop, with each loop being 12feet. Have taken the centre resonating loop as 1/5 of the total circumference which is 24ft, which h works out to 4.8ft. When I connect the VNA to centre loop ,get no reading on the VNA. What could be going wrong.

[@Dallas-Rife-UDX-347-Tennessee]

How many feet off the ground was the antenna for the contacts during the video , and what is the ideal height to put it up permanently? I’m new to HF ,, I’ve been a tech since 2012 , but I’m about to take my general class and get a decent radio but I don’t know the first thing about antennas other than 10 meter/2 meter/440 ,, etc

[@mike-M0MSN]

6 Feet/2 meters the great thing about MagLoops is they do not seem to mind being only a couple of meters off the ground ( i think they need to be a loop diameter above the ground minimum)

[@Dallas-Rife-UDX-347-Tennessee]

@@mike-M0MSN Ok thanks I’ll keep that in mind . Are they directional or omnidirectional ?

[@Anemalwozere]

WHERE DOES ONE FIND THE DESGINS PLEASE 2E0FEH

[@johng7rwf419]

Mike, where did you source the loop capacitor from please? Looks good for high voltages and easily modified. J

[@mike-M0MSN]

A local Radio Amateure (Andy) gave me the one I used however I have been able to copy it and have made others. video coming soon :)

[@gm0sdv]

Gm0sdv build this capacitor

[@77062west]

Question, if you did 4 loops, could you tune to 160 meters?

[@mike-M0MSN]

yes

[@josephsangermano5101]

Double Cooper Loop for 11M Build to

[@juliengirault2549]

Fine Mike, do you have a difference betweeen your EFHW antenna ? 73

[@mike-M0MSN]

Yes the EFHW is a lot more noise and will receive some signals that the Magloop will not, and the Magloop is much quieter and because of this receives signals the EFHW cannot????

[@juliengirault2549]

And in transmission ?

[@R4HKN]

Power transceiver ?

[@anatoltchzen3076]

Un9pi👍👍👍

[@thedancingalien7766]

Us aliens have been looking For that copper pipe for ages Stolen by a human typical Mmm.

[@Justin-bd2dg]

Is this any good for DX?

[@mike-M0MSN]

hopefully