What I did was recommended by MyAntennas for their products, even though I use a much cheaper (yet still amazing) MFJ EFHW. To stop common mode currents if your transformer is up way high, like in my 50’ flat-top deploy, ground the shield of the coax just before it enters the shack. Also, for EFHW’s they use a 49:1 auto transformer, not a 9:1 unun. 14 turns of wire on one side, 2 turns on the other. The formula is : (14x14)/(2x2) = 196/4 = 49:1. The impedance at resonant frequencies on EFHW’s are closer to 2500 ohms. 9:1 ununs are good for non-resonant “random wire” antennas and bring the feed point impedance close enough to 50 ohms that. The swr is 5:1 or less across the HF band, which almost any tuner can handle. If you use a 9:1 unun on a wire cut perfectly to be resonant as an EFHW, it won’t offer enough of a match to get your SWR down on the bands where it’s resonant. Ironic, huh?. Which is why it’s advised you build “random wire” antennas at odd lengths (31’, 41’) to avoid this. Otherwise thx for the video, I’ve had amazing fun with my EFHW, and work 40m and 20m regularly without a tuner across the entirety of both bands with my swr ranging from 1.09-1.4. No tuner required (aside from the all important auto transformer).
@@notgiven3114 there is no “counterpoise quality” of the ground wire, it’s purely to stop common mode current and RF into the shack. Lots of debate about what is the counterpoise in an EFHF, many believe it’s the coax shield itself.
@@notgiven3114 I’m not sure you’re understanding. You don’t set up a counterpoise for an EFHW. You do not measure the efficacy of the counterpoise in an EFHW, and none of the commercial manufacturers recommend deploying a counterpoise. The point behind grounding the shield has nothing to do with the shield being the counterpoise, it has to do with stopping common mode currents running into the shack within the shield. As a matter of fact, I have a choke as you describe as well. My set up works very well. The reason why you ground it before it enters the shack on a high deployment is so you don’t have (in my case) a 50’ long wire running down from your transformer; that’s’ all.
@@notgiven3114 I agree. You seem to take insult where none is communicated, and you seem incapable of accepting an answer given in good faith to your nonsensical question.
The unun you showed is a 49:1 for a EFHW, not a 9:1 so important for folk to ensure they buy/make a 9:1 unun for your recommended wire lengths which need to be non resonant
Hi Mike I just run a cross your u-tube . No 160 meter end fed . What kind of unun and current choke do you think works best for the 160 meter end fed. I did like your video very much . 73 kr4wx
You mentioned nothing about Half Wave end fed antennas, during your otherwise fine presentation, which I enjoyed. I will be receiving a KM4ACK half wave antenna soon. What important information should I know re: the DIFFERENCE between a regular end fed antenna and a half wave end fed antenna, for instance, would I still require the feed line choke balun using the KM3ACK unit? Thank you 73 N4ANO
73, as a german ham i want you to ask - do you know why they (in the Zeppelin) used hydrogen instead of helium? i know! i also would sell no helium to nazi germany this time! thx for this Dokumentation video , you put a mass of work in.! and you done ufb best greez, dg2r?
I’m confused, and new to ham so forgive , but if the coax is acting as part of the antenna, then wouldn’t this be an off-center fed rather than an end-fed?
Maybe why it appears that way to you is that you're seeing the coax as being an extension of the antenna's length. Better to think of it as being akin to the counterpoise at the bottom of a vertical antenna. Picture a 2-meter vertical antenna with three short counterpoise "wire prongs" radiating outwards from the bottom of the vertical part of the antenna. That configuration doesn't look like the counterpoise is an extension of the antenna. Why the coax isn't an extension of the wire antenna is because the transformer at the end of the antenna "separates" it from the coax feed line. Because of this, the transmitter drives the antenna part, not the coax feed line. The reason why there's RF current on the (shield of) the coax is because the antenna is radiating it onto the coax (not because of the transmitter).
@@Superfandangoo I'm sure it was a mistake, and I'm sure Mike meant well. But there is so much other misinformation in the first 6" that I couldn't stand to watch further. Learning about antennas is already a real slog for newbies, without being confused by the contradicting terms and ideas presented in this video. Luckily for them, there's too many other EFHW videos out there.
Just correction, it is UNUN , not UNUM . UNbalance to UNbalance matching transformer. Otherwise good explanation, on how EFHW antenna work.
What I did was recommended by MyAntennas for their products, even though I use a much cheaper (yet still amazing) MFJ EFHW. To stop common mode currents if your transformer is up way high, like in my 50’ flat-top deploy, ground the shield of the coax just before it enters the shack. Also, for EFHW’s they use a 49:1 auto transformer, not a 9:1 unun. 14 turns of wire on one side, 2 turns on the other. The formula is : (14x14)/(2x2) = 196/4 = 49:1. The impedance at resonant frequencies on EFHW’s are closer to 2500 ohms. 9:1 ununs are good for non-resonant “random wire” antennas and bring the feed point impedance close enough to 50 ohms that. The swr is 5:1 or less across the HF band, which almost any tuner can handle. If you use a 9:1 unun on a wire cut perfectly to be resonant as an EFHW, it won’t offer enough of a match to get your SWR down on the bands where it’s resonant. Ironic, huh?. Which is why it’s advised you build “random wire” antennas at odd lengths (31’, 41’) to avoid this. Otherwise thx for the video, I’ve had amazing fun with my EFHW, and work 40m and 20m regularly without a tuner across the entirety of both bands with my swr ranging from 1.09-1.4. No tuner required (aside from the all important auto transformer).
@@notgiven3114 there is no “counterpoise quality” of the ground wire, it’s purely to stop common mode current and RF into the shack. Lots of debate about what is the counterpoise in an EFHF, many believe it’s the coax shield itself.
@@notgiven3114 I’m not sure you’re understanding. You don’t set up a counterpoise for an EFHW. You do not measure the efficacy of the counterpoise in an EFHW, and none of the commercial manufacturers recommend deploying a counterpoise. The point behind grounding the shield has nothing to do with the shield being the counterpoise, it has to do with stopping common mode currents running into the shack within the shield. As a matter of fact, I have a choke as you describe as well. My set up works very well. The reason why you ground it before it enters the shack on a high deployment is so you don’t have (in my case) a 50’ long wire running down from your transformer; that’s’ all.
@@notgiven3114 I agree. You seem to take insult where none is communicated, and you seem incapable of accepting an answer given in good faith to your nonsensical question.
@@notgiven3114 Whatever, troll. Go work on you EFHW’s counterpoise. Lol. Keep deleting your stupid posts too.
Ok. How about you make a video and teach us all.
The unun you showed is a 49:1 for a EFHW, not a 9:1 so important for folk to ensure they buy/make a 9:1 unun for your recommended wire lengths which need to be non resonant
The transformer you showed is a 49:1.
I enjoyed the presentation. Thank you for sharing!
I get 1.1 on almost every band. I do not use a tuner. I use a ICOM 7300 and my antenna 75-10 2K version. 20 feet at shack and 70 feet at other end.
What should be the length of an EFHW 40, 20, 15 and 10m multi band antenna? 73 de vu2eii
UNUN or UMUM a big difference it's UNUN
Hi Mike I just run a cross your u-tube . No 160 meter end fed . What kind of unun and current choke do you think works best for the 160 meter end fed. I did like your video very much . 73 kr4wx
You mentioned nothing about Half Wave end fed antennas, during your otherwise fine presentation, which I enjoyed.
I will be receiving a KM4ACK half wave antenna soon. What important information should I know re: the DIFFERENCE between a regular end fed antenna and a half wave end fed antenna, for instance, would I still require the feed line choke balun using the KM3ACK unit?
Thank you 73
N4ANO
73, as a german ham i want you to ask - do you know why they (in the Zeppelin) used hydrogen instead of helium?
i know!
i also would sell no helium to nazi germany this time!
thx for this Dokumentation video , you put a mass of work in.!
and you done ufb best greez, dg2r?
I know what an UNUN is. But what’s an UNUM ?
De très très bon reportage mais malheureusement jamais traduit donc on zap tous you tube merci
UN-UN. Not Unum! ?? 😂😂😂
I’m confused, and new to ham so forgive , but if the coax is acting as part of the antenna, then wouldn’t this be an off-center fed rather than an end-fed?
Maybe why it appears that way to you is that you're seeing the coax as being an extension of the antenna's length. Better to think of it as being akin to the counterpoise at the bottom of a vertical antenna. Picture a 2-meter vertical antenna with three short counterpoise "wire prongs" radiating outwards from the bottom of the vertical part of the antenna. That configuration doesn't look like the counterpoise is an extension of the antenna.
Why the coax isn't an extension of the wire antenna is because the transformer at the end of the antenna "separates" it from the coax feed line. Because of this, the transmitter drives the antenna part, not the coax feed line. The reason why there's RF current on the (shield of) the coax is because the antenna is radiating it onto the coax (not because of the transmitter).
Thanks Sharing 73
Unun not Unum pronounced un-un.
UNUM - REALLY?
In his slides he spelt it as UNUN so just a slip of the tongue.
@@Superfandangoo No he didn't - he spelled it UNUM and repeated himself several times.
@@gusbernard5215 Yes he did on many of the slides one example here 20:03 spelt correctly 4 times on this one alone.
@@Superfandangoo I'm sure it was a mistake, and I'm sure Mike meant well. But there is so much other misinformation in the first 6" that I couldn't stand to watch further. Learning about antennas is already a real slog for newbies, without being confused by the contradicting terms and ideas presented in this video. Luckily for them, there's too many other EFHW videos out there.
@@gusbernard5215 Yes I could only get so far he is quite contradicting to some of what I thought was correct