Why is it showing a Short Circuit. 49:1 Transformer EFHW 

The first video I've seen in months were the background music level is set perfectly.

Great video Mike. Reinforcing previously gleenend knowlage and theroy.

WOW! Just Learned Few New Things From This Video Alone, What A Great Library Of Videos You Have On radios And Waves, Thank You Mike. :) Subscribed From This Channel To :)

Great video Mike keep up the fantastic work bro

Hi Mike . If i may ? For those who still this is magic , the short exhibits only for DC voltage/current , the voltage/current which our transceivers use to radiate electromagnetic radiations in antenae a.i diferent wavelegnth on amators bands but not only are AC voltage/current . In AC there is no short , are matching and mismatching , frequency, antenae models and feeders types dependent .

Man, this is a life saver - was busy re-cabling my rigs and for some reason I tested my cables and found a short on the EFHW. You saved me a very arduous trip up the roof! :)

Now I know what the compasiter is doing ! oTried mine today! 66’ wire maybe 8’ high at the ends and was S9 into Onterio from east Tn USA.

Ok that was informative. Didn’t know about the tap version. Now I want to build it to see if there is any difference at my qth. Thanks

Perfect.. Now do a magnetic loop Mike! :)

First off, thank you Mike. Your videos are very informative and have helped me understand concepts which are normally only glazed over by many other videos and documents I’ve read. I’ve attempted to build an EFHW using the DX Commander 10M pole and a 49:1 Palomar transformer with no success, and I’m a bit lost. I also purchased a 64:1 from Cal that you made for him. I’ve only used my Comet SWR meter thus far as I don’t believe the 64:1 would take much power and was going to use it for an RX antenna. For simplicity, I made a 10M 1/2 wave element, which I cut for 28.5MHz both taking into account Calum’s end-effect formula, and without. I’ve used a ground rod, an 8 element radial field, both, and none. I only wanted to use a single band, in this case 10M to keep it simple. I also attempted a 20M 1/2 wave, cut for 14.250MHz, with no success. The issue is my SWR is off the chart, no where close to my tuned cuts. I’m using a 3 foot jumper from the antenna to my meter. I’m going to use the entire length of coax which is around 150ft or so. I also plan to use my VNA and shoot the coax for length just to understand what I’m dealing with. Also my meter and jumper work great when testing my DXC 12.4 which uses 1/4 wave elements as spec’d by Calum. Summary: using a 49:1 from Palomar, or your 64:1 with a ground rod and or radials, my SWR is infinity on 10M, but its in tune tune at 14.4Mhz, which would a 1/4 wave on a 4.95M long element using DX50. The values for R and X from the meter are below. R=5 X=44 SWR=♾️ Any ideas Mike? Thanks

Good job Mike! 73 to PY2SNN.

I always remember my Elmer's words: RF doesn't recognize a DC short

Fascinating Mike - really excellent resource, thanks! How is the heat pump coming on. Mark.

Mike, I really like watching your build videos and this one, for whatever reason, punched thru my cranium to where I understand how the 49:1 works. Have you built 4:1 Baluns, for loops? There's a 2.5:1 balun, known as the "Talented Balun", that is supposed to be spectacular. The reason, as the ham who markets that balun says, is a skyloop antenna is actually 125 ohms, and a 2:5:1 balun, not a 4:1, is perfect match for 50-ohm coax. Thanks for the videos and the work you put into them.👍👍

Thank you for explaining how an impedance transformer is wrapped. I would like to know what is the value and rating of the added capacitor ?

Thanks

Hi @mike-M0MSN, after this video, I decided to create a new 49:1 Un, and I used 2 pieces of 240/43 Amidon Troid in the beginning of the winding, using a single winding, just like you, without using double wire, using the wire used in 2mm enamel-coated copper windings. I created a beautiful Flour with , and since the thyroids did not fully kiss, I combined the Troids that I leveled with sandpaper on the glass, and after covering the Troid ring with heat-resistant teflon wrapped around the taps and a few turns of teflon, I created the winding. I combined it very well, but even if I used different lengths of wire in Nano VNA. SWR is affected very little, SWR is infinite in the bands I want, when I make broadband measurements between 100Khz and 1Ghz, SWR 1.0 at 700 MHz, when I measure between 100Khz and 100Mhz, SWR 1.1 at 67.1MHz, and when I measure between 100KHZ and 30MHz, SWR 1.1 at 1.150Mhz and 5.800Mhz. Swr 1.1 at Hz Without grounding the measurements are worse, a good ground connection is required. Listening on CB is very nice. I did not do TX because SWR is infinite. I wanted to do a different experiment and created a connector from UNUN's chassis and antenna end, which I used to connect the antenna side to the radio, and made a reverse connection to the radio. I connected the antenna to the input end. SSB also provides zero interference and perfect listening. When I try to connect the capacitor, it weakens the listening and the interference rate increases. It amplifies, listening without a capacitor is great. I'm trying to understand my problem, it was built with 2mm enameled copper wire in the same way as yours, the only difference is this, do you have any suggestions for me?

What was the value of the capacitor Mike...brilliant informative video.....

Great presentation. I’ve always thought the coil was needed at 2.1m up the radiator. Some people have used long counterpoises. Essentially creating an ocf or half square with these. I’ve never noticed any real differences doing that other than throwing the swr into fits. Have you used long radials with the unun?

Lots of good info for winding the 49:1. Some question for the earthing, if a stake or counterpoise is used what difference do these make? And in your 1st diagram where the windings are sepatated, if the aerial side is earthed but the coax side is not, does this work better?

Mike have you ever tried a 3x wavelength end fed ?? With say a 64:1 or greater balun ? My buddy is running one on low band with a parasitic radiator below it at 60’ height I believe in a inverted L shape and with 1k he does pretty well. He’s not a DX er so can’t attest how well it works out far 😊

I like that. 2 toroids and a large wire. How much power do you think that will handle? I have some 240-43's and some 14 gauge wire, not sure what that is in mm. But it is about the size you have there. I am not sure if I should use 2 or 3 toroids. 73 W4DES

Great video thanks. What value capacitor is that one you used please?

How are the Smith graph radiation patterns produced. Is it conjecture or something that can actually be seen with some kind of instrument or device? I have been able to see the static charge patter on a charged pvc pipe using ashes sprinkled about the pipe and saw the ghost. It was a series of torroids up and down the pipe which can be discharged like individual cells by putting a light bulb or my finger near each one and hear the click as they are discharged. People think I am crazy and asking too many questions which will not even be on the extra exam anyway. I have to wonder if dusting ashes over my antenna array would show me the pattern which I am wanting to see. I have asked Callum & he thought this is a question for you. Thanks for the education. Mike

Excellent video Mike. When you said that the tapped version works better than the coupled version. In what way does it work better? Thanks

Great presentation Mike thank you ... on the VNA test , what did you use as terminating resistor ? Or was this test on the antenna it self ? Also wondering if you have done any efficiency tests ? Thanks Niels / OZ1CGQ

what were the size of those 43 mix toroids?... or maybe you have a link right to them?

Autotransformer..... I wonder if a variac would work?

Why the hell don't my end fed transformers ever look as good as yours Mike? Must try the tapping version...

I think I’m slowly starting to understand how these transformers are wound. Question, in a power transformer, increasing the amount of turns improves efficiency, is it similar with RF? Aka, would a 200 to 1400 turns transformer perform “better”, and in what regard? Increasing the wire gauge improves current capacity, and increasing the toroid size improves efficiency, but what does the amount of turns do? Another thing I wondered about is what would happen if you increase the insulation thickness (for example if you’d use normal single insulated house wire), and if solid vs stranded vs litz wire affects things? 73 OH6ZA

Hi Mike, Ive just bought a Nanovna and im wondering what software you are using when connected to the pc? Thanks.

8:10 You said it is 2,800 Ohms to 50 Ohms but I always built my antennas to match 2,450 Ohms on Mmana Gal. Which is correct?

Hi Mike... The thing I can't get my head around is - back end of the 70's early 80's on CB as a school leaver, the threat of a pin through the coax to blow a wally's rig up was regarded as a true fact? Fast forward to today, with a full licence, that back then believable true but untested fact has always stuck with me and I can't compute how a direct short on the first 2 windes of the transformer doesn't do the same as it shorts the centre to the braid just like a pin through the coax would? OR was that just a myth from people who thought they knew more than they did?

do you make and sell these at all

So it's a DC short and we don't care since it's not an AC (RF) short. But what is it? What is the total unloaded input impedance of the desired spectrum?

ferrite type