EFHW Antenna / Transformer Ratios, It's too Easy!

This is just a quick example or three of how you can determine what ratio End Fed Half Wave antenna you have.
It's as easy as Turns Squared!
This is useful for a few different reasons.. "My End Fed isn't working". You then look at it and realize the EFHW was made with a large number of turns missing.
Or maybe you have a practical application or reason for a 49:1 over something like a 64:1. I don't know, but I can show you how to tell.
Enjoy!
#hamradio #antenna #qrznow

[@chuckmartin6049]

You are the first person to say count the turns on the inside. My brain doesn't hurt anymore

[@W9HJBill]

Dude, you are hitting it out of the park lately. You are covering topics that while may have been done long ago (and honestly, I don't remember this being covered in this way going back to 7 years ago), it's good that new videos like this and how to determine if a core is proper mix or not because there are a ton of new hams and old videos get stale and people won't see them.

[@peterzivcic]

what the heck? a random guy comes and out of nowhere gives perfect answers to all my long time questions? Dude, thanks a lot! definitely subscribing 😉

[@bob.kd9idd]

1:64 ........ Great video. The key is to learn something new everyday. So keep teaching this new ham a thing or two. Just got my DX10. And just finished your series on the DX10. Keep up the great work.

[@philhayward8696]

Thank you for that. In the space of a 5 minute video you have taught me something that I have struggled to get my head around for a very long time. Excellent stuff......keep it coming. Cheers ZL2VTH

[@HAMRADIODUDE]

Glad I could help!

[@hshpegel]

Thank you for this tutorial on ratios. I was struggling it and you explanation cleared it right up for me, 73.

[@45auto]

I was always warned not to math in the comments section (64:1). Nice explanation!

[@berndkonemann5049]

Short and to the point. Baluns become clearer... I forgott or missed something in the past, how the square gets into the rule. Video well done, thank you.

[@WaynesWorld69]

Please do more like this! You've made it easy to understand. Thanks so much!

[@IncognitaLabs]

Take (secondary turns) divided by (primary turns) and then square the result and then multiply that result by 50 giving you the ohms value the transformer will match. i.e. If secondary is 21 turns and primary is 3 turns Then 21/3 = 7 Now square 7 and get 49 Now multiply 49 by 50 and your transformer will match 2450 ohms If secondary is 14 turns and primary is 2 turns Then 14/2 = 7 Now square 7 and get 49 Now multiply 49 by 50 and your transformer will match 2450 ohms If secondary is 24 turns and primary is 3 turns Then 24/3 = 8 Now square 8 and get 64 Now multiply 64 by 50 and your transformer will match 3200 ohms If secondary is 19 turns and primary is 3 turns Then 19/3 = 6.33 Now square 6.33 and get 40.07 Now multiply 40.07 by 50 and your transformer will match 2003.5 ohms If you put 3 turns on the primary and say 26 turns on the secondary and put taps on the secondary windings starting at say 18 turns the resulting matches for each tap will be... tap 26 = 3753 ohms tap 25 = 3471 ohms tap 24 = 3200 ohms this is the common 64:1 tap 23 = 2936 ohms tap 22 = 2688 ohms tap 21 = 2450 ohms this is the common 49:1 tap 20 = 2220 ohms tap 19 = 2005 ohms tap 18 = 1800 ohms Selecting the best tap for lowest swr is easy and you have what amounts to a very simple manual tuner. This can be further refined by making the first several feet of your longwire using something like very small multi-stranded stainless steel aircraft control cable. If you wind this cable onto a spool of some design then you can change the actual antenna length without cutting the wire, the turns all short out and don't create an inductance...if the wire was insulated you would be adjusting both antenna length and inductance and you want only to change length. Using stainless steel cable prevents rust and/or corrosion. If you have your toroid mounted on a piece of plastic as is typical then just cut two slots in the plastic to serve as the spool. This is easier than adjusting the end of your wire by folding it back since the adjustment can be made close to the operating position with no need to lower the antenna. This makes it easy to cover both 80 and 75 meters for example. Combining the taps with easily adjustable wire length results in an antenna for the field that can match any HF band with a very low swr... if you use a spectrum analyzer you will see that changing the wire length moves all the harmonic dips either up or down in frequency. And changing the tap then refines the match lower or higher in relation to the radios 50 ohms. I hope my math is OK, I just used the google calculator and did a quick check on this post, but you can see what I'm doing here :-)

[@jps99]

Great video, as a new ham working on my first antenna I found this very helpful! Earned my subscription!

[@K6ARK]

I have found that a 40:1 or 44:1 transformer gives the best match with my little QRP kits and a 40m EFHW. I use 3:19 or 3:20 turns ratio.

[@owlcricker-k7ulm]

Thank Dude, I am working with a bunch of new hams and your videos are a great help while they are building EFHWs. Saves me time for other things. 73 Bro

[@Siskiyous6]

BAM! Dude that was the best description of this I have come across. Enjoy Hamvention!

[@DirtyPlumbus]

I could watch an hour more of this. 👍

[@HAMRADIODUDE]

Thank you

[@mikemiles3068]

Great video and you did an excellent job explaining and the 3 /24 turns would on of my favorite 64 / 1. 👍73 KV5P

[@rq6884]

Nice work on this video! I learned something. Thanks

[@nobodynoone2500]

Good stuff. Thank you.

[@JasonDrennen]

1\64 if that's right holy s*** dude thank you. You made that very easy.

[@HAMRADIODUDE]

You got it

[@thork0tjt515]

Thanks. I learned something today!

[@RixtronixLAB]

Creative video, like it ,thanks for sharing:)

[@gravestonemyth]

Thanks. Very helpful.

[@donaldsmith3048]

I just made one, after the 14 turns I put a tap and 2 more turns for 64:1. That gives me 49:1 and 64:1. What ever tunes up the best. Putting my antenna low, I think I should have put in a 36:1 tap in there. Lower antennas sometimes have lower impedance. But I didn't think of that. It is made up and not taking it down to do that.

[@clark8250]

Holy crap this made sense and I get it now

[@keiths7929]

You're a boss. Excellent video.

[@ty81060]

There was no VHF radio included when we bought our sailboat a few weeks ago. I live in Ontario Canada and since I’m considering a Ham radio licence in the not too distant future I’ve decided to buy a “handheld” VHF / UHF dual band radio that is of decent quality with features enough to suit my needs for now. One of the features my new handheld radio “must” have is the ability to connect to an external antenna. After purchasing a radio I will buy and install an antenna on the top of the mast that’s designed to work well with that radio. Then I will run the cable {or cables} to the cockpit and cabin area’s and install permanent connections so I can connect my handheld when I’m in either location. I’ve been a boater for more than 40 years but always had a permanently installed VHF with my previous boats. Realizing I’m only able to transmit using VHF until I’m licenced for UHF here in Canada, it will still be nice to pass some time having the ability to monitor UHF during our travels. Even though I’ve been doing a lot of reading about the different brands models and features, and despite watching several videos it seems a bit like information overload and honestly I’m feeling a bit lost trying to keep all the technical details straight but I must make a decision in the coming days because we’re launching our boat and I don’t want to be on the water without a working radio. I would appreciate suggestions from those of you who have the experience and knowledge in this area. Perhaps you could offer a few good quality brands with the model numbers ranging in price from $100 - $150 {willing to spend more if justified} you feel would overall work well for use in my sailboat as well as my home. Once I obtain my Ham Radio licence in Canada I will also install an external antenna at home and this should get me started. Then after some hands on experience I will have a better understanding enabling me to make informed decisions later when it’s time upgrade. Thanks in advance for your help and suggestions! Regards Tyler

[@aldewitt9]

Another terrific video!

[@robertmeyer4744]

that great. last one is 64:1 I find that better with 80/160 meters with type 43 ferrite. less heating. that the hardest part. telling the ferrite types apart. have to test like on a known VNA . don't need twist on primary to secondary. in fact only one 14 turn winding needed, put a tap on 2 turns . auto transformer 49:1 . and that a UNUN . 73's

[@williambrooks6629]

Great video. The example you gave is 64:1. Am building a Good Guys EFHW (clone) and want to know why it has a 64:1 ratio. One of the comments gives a formula and it turns (no pun intended) out 3200ohms is the impedance it matches to a 50ohm coax. Someone also mentioned putting in a tap to give the option of 49:1 - 2450ohms and I think that is a good idea. Thanks very much for the easy to understand description. I will subscribe. 73 vk5wb.

[@HAMRADIODUDE]

I really want to do the tap soon. I made a video on the x-tenna, which includes a switch between 49:1, 56:1, and 64:1 - and I think it's an amazing concept, just need to find a suitable switch. Cheers.

[@K3JRZOnTheAir]

Awesome info!

[@WillShattuck]

64:1. Thanks ! :-)

[@1010fairchild]

FINALLY!!!

[@RandallRash]

Awesome Dude!! Thanks for the simple explanation. 73 - KR5EEE

[@DonzLockz]

Good video Sean... now I can do math... I hated math. lol

[@K9KMVTheUnluckyHam]

Great explanation Dude! Thanks for the video. And I think the answer is 64:1 ?

[@ozone385]

64:1

[@k2exe]

The real question is how do you count them if they are under shrink wrap

[@k2exe]

Any tricks? Or easier to hook up a meter?

[@jackK5FIT]

64:1

[@mattstosh6960]

Most Excellent. More pleaase.... What number/type of Torrid do I use. What gauge wire? etc..

[@K6ARK]

-43 or -52 mix are best for EFHW and other ununs for antenna feed points. -43 is the most common. Size should be selected based o power handling required. Sizes are generally measured in hundredths of an inch in outer, so an FT50-43 is half an inch in diameter. 50 size toroids are good for 5-10 watts depending on duty cycle, 140 size toroids are good for around 50 watts. stack a couple together for a solid 100w transformer. Wire gauge doesn't have to be as large as many people think 26 ga is generally enough for 100w, although 20-22 ga provides a nicer fit and will be slightly more efficient on a 140 toroid. I use 26 ga in my QRP kits with a 50 size toroid.

[@mattstosh6960]

@@K6ARK OK. Please talk to me as you would a child. Very ignorant. So I have sitting in front of me several Amidon FT-240-43 torrids. By your statement: -43 or -52 then these would be OK to use? So then... the amidon (FT-240-J) and (FT-240-77) and (FB-31-2401) would not work. Correct? Where does one learn these arcane arts? Tank you. 73

[@K6ARK]

@@mattstosh6960 no problem. -J material (also known as -75), -77 material, and -31 material are better suited for common mode choke applications. You could try using them in a broadband transformer like a 49:1 unun, but would likely have greater losses and poor performance on at least some bands. I learned about this stuff but reading material from Palomar Engineering and other sites with analysis and research on ferrite materials.

[@straypacket]

@@mattstosh6960 Palomar Engineers website has a couple documents that describe uses for different ferrite mixes.

[@brianjrichman]

Dude! These are transformers, not antennas. The wire and the transformer together make up an antenna system. That said, your counting turns is correct. I made up just such an antenna transformer at the weekend by the way...

[@matthewday7565]

Not seen a transformer toroid core wound with a crossover before, I know you do it with choke baluns to reduce end to end capacitance

[@ralph9987]

Interesting. Have tried a 49:1 unun that is tapped and not bifilar? Swr, loss...etc?

[@daveengstrom9250]

What I don't get are the terms "balanced" or "unbalanced" as far as feedlines or baluns or ununs. What makes it balanced or not?

[@paulkazjack]

Can i use a toroid for a 10m quarterwave vertical for 40metres? How many turns are needed? Thanks

[@TheCablebill]

Why do you square the numerator?

[@rbryanhull]

64:1?

[@horus2369]

1:64

[@Mikej1592]

(64:1) but what if the primary wires are made of lead coated copper, and the secondary is made of gold plated platinum wire? What if you store the coils in a bath of liquid nitrogen? What if its a full moon in Japan and my dog barks at the people walking by on a Tuesday and the coils are imaginary?

[@jhooz2858]

36:1

[@ahendrix9787]

...something confusing beautifully explained!!!...thank you!!! 73! de KO4UMY

[@W3OY-RAY]

64:1. Great explanation. 73 de W3OY