Ham Radio - The doublet vs EFHW noise rejection comparison.

Is your center support conductive? Does it matter?

I hear you on the health issues. Same here for 3 weeks in August. OK now to learn more about HAM radio.

So during the apocalypse we need a half wave to find all the hidden bunkers eh. Or a way to shield them so that we are less detectable :)

2 thoughts: The doublet is less noisy, compared to the EFHW, because your Z-Matching Tuner is acting as a Passband-Filter. Everything around the tuned center frequency is attenuated by the tuner, while the EFHW is broadbanded. EFHW has it´s SWR Minimas at desired Bands, but usually does not go above SWR of 3 between the harmonics. Second thought: Use real parallel Wire, not this wireman excuse of a feeding line. This will increase efficiency of the Antenna considerably. The Way the wireman cable is designed, it interacts with the 2 wires as dielectricum and will cost you some energy loss. Once you´ve tried 2 parallel wires with just some spacers every couple of feet or so, you will never go back ;) At my QRZ com page, there´s a picture of the feeding point of my doublet, showing also 2 spacers..... There is no conecction between my feeder and my Antenna, as it is one continuous wire..... 73 Manuel; DL2MAN

I have been a 3 year efhw antenna fan but your detailed sharing of your experience here has my eyes wide open as to what I would like to try next. Would you share wire types, open line specs and length so as to approximate what worked well for you at 120' of span. Thanks...

Thanks Kevin, I am in process to change up antennas and both are in consideration!

Excellent experiment... Have you tried a Sky loop yet? I've heard it has the lowest noise and best gain for a wire. Thoughts??

Thanks for sharing. I heard a RF engineer explain that doublets are inherently better for low noise. Mainly because they are horizontally polarized. All the RF noise we from the other RVs is vertically polarized (according to the RF engineer all the noise that we have deal with as hams in an urban environment is typically vertical). In the little talk, he went on to say that you can run other antennas like an end fed for example. You can run that horizontally, but it is not horizontal polarization, it's still vertical. And thus you'll have more noise with end feds. Anyhow, I have good luck with a doublet fed with ladder line and I think it's still my favorite antenna. And literally the most simple. Two wires I cut from a spool of wire from Home Depot!

I'm sold.

Just stick a common mode choke on the feedline to the endfed

COVID gave me a cough for 6 months. Good video

Please do a metal detecting video

clicked off after seeing 4:1 balun

will 49:1 worked?

Dear Kevin happy 2023! My respect for whole great effort you are providing for HAMs education in social media. My question is concerning type of cores you've used for transformer displayed here. 73! SQ5OBV

Recently found your very informative channel! Thanks for sharing all this great insight. :)
Would be great to get your thoughts or even a video comparing this doublet to the folded dipole you made with windowline / ladder line in an earlier video.

What are all those people doing out there in the Desert with Caravans......Are they Gypsies ?

Kevin, great vid.! Q; At what height does the doublet hang ? is that critical ?

As you say a fantastic shortwave antenna.I would never go back to using a coax fed antenna.The noise difference between the two is night and day.🐒🐻🤗👍

I also very much like the doublet but have come to favor a closed loop horizontall sky loop up 40 ft fed with twin lead and tuned with a true balance tuner. A whole S unit quieter than most other antennas!

OK. Do you like the doublet? Love my MFJ 1785 rotatable di-pole which I don't rotate. Great figure "8" pattern, but it needs TLC so I put up a Horse Fence inverted "V" and you're spot on.
80 is great, 40 a little less but still made tons of contacts on 20 this last contest. But it's just a little noisier than the 20/40/80 rotatable.
FYI- the MFJ-1785 works great and it has "whiskers like bicycle spokes for capacitance and after 5- 6 of hot summers and cold winters they have tendency to fall out or get loose which makes tuning next to impossible, thus the wire till it is fixed. Trying a Palomar 9:1 end fed tomorrow

Have you ever tried to hook the ladder line directly to the antenna matcher? Just curious Thanks Bob. KC9LRA .

Maybe its AGC, you have it set to slow.. AGC if the signal is low on one antenna will crank up the gains. But evern f thats the case it means the HWEF is recieving lessand cranking AGC up

Nice video. I have a 40m loop with 4:1 balun same as yours. Fed with coax and works well on 40-6m but id like to try this doublet!! Cheers. VK2VRJ Richard

Great Video!

I have been tempted to put up a doublet as I have all the materials eg wire, 300 twinlead & 450 ladder line.

But the guy's saga of using twisted-pair speaker wire intrigues me.

So I'll start with a simple twisted-pair portable doublet.

Kevin did you by any chance take photos of those 2 chokes when you were building it and how they wrapped around from one to the other? if so can you share ? I am currently using the Hygain av-680 and love it , but the qrm here in the middle of Los Angeles is nasty , plus it sits 75 feet away from power lines. Really want to make one of those for the qrm reduction. I have built baluns before , but can use help on how you connected them. THANK YOU

Isn’t one side supposed to be shorter than the other?

I also really like doublets but don't have much room on my property. I've tried the 49:1 EFHW and like you, I've noticed it was much noisier a doublet.

The one thing with a doublet that is important to note is that the feed line acts as a matching section of sorts. This is why some folks have trouble finding a feed line length that works on ALL of the bands they want to operate on.

Can you tell us exactly what 450 ohm feed line your using and how long it is?

Hi, Kevin. Liked your video. Maybe I missed it but what is the length of the ladder line on your doublet? I would like to do a doublet with only 25 feet of ladder line. What do you think of this? Alan KZ6B

I had a short Carolina Windom. I friend gave me a "Condo Buster" OCFD he got on ebay cut for 20m and up. Once I replaced the coax with 450 Ohm line it became my favorite QRP antenna. I got it stuck in a tree and pulled it apart.
Since then I've been using an EFHW 80m-10m and loving it.
I got a 53ft random wire antenna at the same time and tried it a few times, but haven't been too impressed, but I haven't tried working with to optimize it.
I did work to optimize the EFHW. Steve Ellington's suggestion about choking and grounding at the transformer made it my go to antenna.
I've been using the Chameleon Emcom III portable and it hasn't impressed me. Even after working with various configurations.
I have the pieces to build a double, but I haven't done it. As I live in a condo and mostly operate portable at parks I will probably cut it for 40m and up starting >=3/8wl of 40m.
My main motivation is ECOM with a focus on 80m NVIS, so I don't see me self giving up the 80m-10m EFHW. Its too simple to deploy and it works well, even if it is a little noisy.

Very good video... i must have missed how long your 450 ohm ladder line is. Can you please let me know? Thanks again - great video.

What length is the balance feed line? What formula do you use to compute the length?

I have trees that I can put one in they are 160' apart and I can put the antenna 120' feet up. What are your thoughts?

We're fans of Quartzsite too. But I just got into HF about two months ago and was looking forward to our next Quartzsite trip - and bringing my FT-710. However, our trailer runs from 700 watts on the roof, an MPPT controller into two 100 ah Lithium batteries which keep my pure sine wave inverter on that runs our 120v ac fridge (a small RV size but still ac). Hmm. I run a permanent Vibroplex endfedz 135' wire antenna here at home, but I've been wondering what kind of antenna I could take with us on our next south trip. Your simple-looking "doublet" seems to be a good solution. I'll find a good description of how to build this and give it a try. Thanks for your video. Never thought my inverter would be a problem - and it hasn't been until now - ha.

I too love my double Zepp (doublet) antenna for all the reasons cited, but there is one thing I noticed when I got a new radio, there is "RF in The Shack" and therefore everything, the radio and the tuner MUST be properly grounded. On many radios (especially tube types), the only problem is getting "bit" or "burned" by the RF, but with my new radio and tuner, the RF gets into the radio and somehow messes up the tuner too. After taking down the antenna and looking for problems at the termination and feed line (and finding none), it finally dawned on me that I had to ground the radio and the tuner per the bolts and nuts provided on them just for that. Proper grounding solved ALL the problems I was having including "RF in the shack."

Swith the wires locations to be sure the doublet results aren't just the results of it's orientation. EFHWs twnd to be in a slope and pick up more man made emi as it's vertically polarized so a dipole/doublet will seem better but a vertical dipole vs a horizontal EFHW will show different results.

Whats the difference between window line and ladder line?

I had very similar results. 60 ft EFHW vs 60 ft doublet, 600 ohm ladder line in to the my room, MFJ 986 roller tuner above my radio. With doublet noise level decreased about 1-3 S-units on different bands. And it may work anywhere with that tuner beginning from 3.5 Mhz (from 5 Mhz with good efficiency), and up to 51 Mhz. Of course, above 21 Mhz the diagram might be some strange, funny and unpredictable, but if I hear somebody, I work with somebody. 73!

Very informative, thank you

After literally decades of trying just about every common HF antenna design there is I too have settled on the doublet....it's GREAT...love it! Mine is 140', fed with homebrew ladder line and ATR-30 tuner. I found that it tunes everywhere, including 160m. Over several months of testing it consistently beat my OCF 80m coax-fed dipole so I took that antenna down. Forget all the rest, the doublet is far and away the best.

How do you get water out there? Well done on the video, thank you!

I run a 160-meter doublet up at 80 feet, into about 80 feet of windowline (450-Ohm), into a 4:1 current balun at about 14 feet up. Then, 50-ohm coax is suspended from the 4:1 current balun to the eaves of the house, down to a grounding block (tied into the house ground system), then into the radio shack to a match box (Dentron). Then, to my IC-7610. This wire antenna has out performed all other wire antennas I have ever used. Much more quiet, and I've worked ALL ZONES (WAZ) with it. It works quite well on nearly all HF bands, slightly on 6 meters.

Thank you . been looking forthis info for a while. What mfj tuner has the built in balun (Or which ones do)

can a douplet be shortened as linear loaded dipole?

I have built the lots of doublets as well as the full wave horizontal loops for multi band operation. Both are good multi band antennas and the largest I built was to operate down to 500 khz. My current ones are resonant on 1.9 MHz with the doublet inverted V at 70 ft and the horizontal loop at 45 ft.

Really appreciate this one. Definitely going to reconsider my EFHW as my main antenna.

Just over a month ago I replaced my previous fan dipole (75/40/20 m) with a 132' doublet. It is fed with 45' of 450 ohm window line coming right into the shack to a Balun Designs 4115T balun, then 18 inches of coax jumper to the tuner. I can tune most of the bands from 80 to 12 meters. I can't tune 160 m, but wasn't expecting to. Nor can I tune 60 m or 10 m. I'm really surprised at not being able to use those two bands. I may try adding some more feedline.

My favorite antenna I ever had was a, I think 150' doublet. My tuner had a built in balun of unknown ratio. On at least 2 bands, I could just bypass the tuner. It was between 75-100 ft high slanted at about the angle of the side of the hill I was on. The top end of the antenna was at least 75 feet above the ground, but the bottom end was lower than the top end, but closer to 100 feet above ground where it was.

I owned any frequency I worked with my Swan 350. When I got an 817, I made a test call in a DX pileup and the DX station called me on my first call.

I was often the desired QRP station in the paper-chaser nets.

I'm setting up again, here at my new apartment and I put up a small doublet against the side of the house, just to hear what's on the air. 20/15 are perfect matches, the others don't match. But, it's just there so I can at least listen. I'm hoping to have a real antenna up in the next week or two.

Looking forward to working you!
72's and 73's
N4PGW

Have you tried the efhw with a common mode choke?