Ham Radio - The Doublet antenna, QSOs and observations.

Thoughts and observations after using the doublet for awhile. Plus a couple of QSOs, one of which was stellar.
Original design and build video:
• Ham Radio - The Double...
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[@Ragchewer]

I bought the DX Engineering 160 meter dipole kit. They said to cut it down to 220 feet for a doublet. Wow! All 11 ham bands work like a dream using my MFJ-998 automatic tuner (internal tuner on 6 meters). I extended the supplied 100 feet of 300 ohm ladder line to 180 feet to reach my shack. 6 feet of RG-213 from a 4:1 balun into the tuner does the trick. This is the best HF antenna I've ever used! I can run legal limit on 160-10 meters into the sloping doublet that rises from 50 feet to 100 feet into a tall tree. Noise levels are quite low; I'm blessed! W6PDL

[@timg5tm941]

The best Multiband you can build. Great video 73

[@erikheidt4132]

The Doublet is one of the hidden gems. Mine is remote tuned with an AH-4 antenna tuner and constructed using a kit from DXEnginnering that included the window line and hardware. These can be great stealth antennas!

[@timg5tm941]

Erik Heidt couldn’t agree more. They knock spots off 9:1 random wires for sure.

[@jack002tuber]

Capetown! What a QSO, congrats!

[@Cardassiaprime]

One of the most complete and informative (and not to mention entertaining) antenna videos I have ever seen, thankyou for sharing Kevin, Barnie M7PBX.

[@HamRadioCrashCourse]

Fantastic! I'm very impressed Kevin, what a great contact!

[@survivalcomms]

I have been running an 80m doublet for 20 years now and for a simple wire antenna it is the way to go. Thanks for sharing !

[@Daniel-M7BCE]

Brilliant video as always Kevin!

[@m1cxf]

Hi Kevin, really enjoy watching your clips. I have been using doublets for many years and when portable I use one totally made from speaker wire (figure 8) including the feed, no need to solder and weatherproof any joints. I have never looked at any technical figures, it just gets used as is and it works.

[@tomroderick8213]

Excellent video Kevin. I got back on HF in 2016 after a couple of decades hiatus. Put up a 115 foot doublet fed with 300 ohm twin lead and a remote SGC tuner out doors. Better than any HF antenna from the "old days" and can use it on everything from 80 meters through 10 and even got it to tune on 6 although that tuner is not rated for 6. Been watching your videos for a while on my Roku box, but decided to come on down to the shack tonight so I could subscribe and comment. 73

[@ae1tpa92gwtom2]

Excellent Job Kevin,...I had the opportunity bk in August running 80W and 897D on a sloper from my place in Bulgaria to speak with Rob, getting thru the Pileup, I had a great smile after that contact and a self Wahoo, as well,.. cheers n 73s LZ/AE1TP A92GW,.. congrats Kevin,.. good on ya!! 😉

[@mikemcdonald5147]

WOW Impressive!!!! Love it. and congrats on the contact.

[@SevenFortyOne]

I tried working Rob portable a month or so ago from CT but couldn't bust the pile-up. I too was running 30W but was using a dipole in the trees at a park. Great catch and proves your doublet is working well! A few of the guys in my club have been running doublets for years with lots of success.

[@davidsradioroom9678]

I will have to look into this antenna. Thanks for sharing.

[@georgeriedel9357]

Great videos both the build and this one. I use 600 ohm TRU LADDER LINE for my 1,500 ft LOOP and is awesome!! Thanks

[@Mike500912]

Hi Kevin, really enjoyed this video of you sitting in 5-6 deg C temps. Made me feel somewhat cooler while sitting here in Australia with 45.7 C (114.3 F) :o) It's so smokey outside with the bush fires, just chilling inside under the aircon catching up with youtube subscription viewing.

[@robertgrant1424]

Hi Kevin, I really enjoy your page! I am using an 80M doublet also with a homebrew link coupled tuner. My next goal is to get it considerably higher in the air because height is might lol. As you now know now it is an efficient antenna system. I run window line into the shack with no RF problems in the shack. I am building a basic RF ammeter into the tuner to check feedline balance with toroidal current transformers. For light weight antenna wire I use 1/16'' mig welding wire 5365 aluminum alloy its cheap stealthy and strong.

[@forthy62]

Great video. Just started to order the parts to build a doublet too. Good that I never gave my two manuell tuners away, which both have a connector for the latterline :-) 73, Stephan, DF6PA

[@thuff3207]

Loss management goes a long way to help efficiency. That in itself can help to get more energy out. So thanks for this video.

[@harveypiper3268]

Excellent Kevin! thank you, I really found this interesting. I will put one up myself.

[@M0RMY]

Hi Kevin. Great QSO into SA! It's a weird blind spot for me from my QTH. The doublet is working very well and demonstrates that with relatively few bits of wire and some patience, you can build a fantastic antenna. When Callum sees this maybe we will get his doublet up quicker!! Happy Christmas mate. Tom M0RMY

[@MatthiasLenardt]

OK ... for sure I also watched part 2 🙂 thanks for sharing 👍

[@NICKGAR7]

Nice one Kevin. I use a 2 x 27m doublet with 450 ladder line out portable (mainly 80m and 40m (extended double zep on 40)) and ‘yes’ the tune does drift a bit as the feeder gets wet. I use a quality balanced tuner and love the ability to be able to use it all band with relatively straight forward cheap $40 antenna. Cheers, Nick M1DDD / G5EA

[@redstickham6394]

I had a similar antenna in my attic for a while. Mine was a 60 foot dipole that was bent into a rectangle, aka a half wave open loop. I fed it with some old Radio Shack 300ohm TV twin lead and it worked pretty well. It had some strange radiation characteristics, like not much signal to the northwest on 20 and same towards South America on 15. I did often work Australia on 30 in the morning and Japan on 17. I fed with it twin lead to an MFJ balun connected to my LDG Z11PRO autotuner with a barrel connector. I had to take it down when I was having work done in my attic and never put it back up. Planning on putting some similar up there soon.

[@russblahetka4742]

Another great video! You look like a Jedi master in that hoodie.

[@fernandoscrenci4874]

Great Video on Haming it Up!!

[@ElektroLUDIKITS]

I really love the fact that you run the fair amount of power to make the contact with South-Africa!

[@loughkb]

Well, it's more for battery life than anything else. But I've always stayed low on RF power, and just ease it up as needed anyway. Why push the rig at max if you don't have to? It will run cooler and the fan won't spin up as much.

[@Inkling777]

If your attic is big enough, doublets should work well for those constrained by HOAs. One antenna and feedline will give you multiple bands.

[@Tryke_Ryder]

Good snag on the South Africa! My wife grew up near Kalamazoo Michigan, but she didn’t get her license until she came to Kansas (KB0IDA). De WO0E.

[@renohuskerdu4592]

Amazing. I plan to try this. Hats off to your wife, she must be very understanding, with all the radio shack stuff in there.

[@loughkb]

No wife, divorced. Once was enough for me.

[@edpetrovski6640]

Put up two five eighths wave in phase doublet fed with 450 ohm open wire for 75 meters with the center at 70 ft, one end at 45 ft and the other at about 10 ft. Europe on 75 was common at night.....and several "strongest signal from North America" reports. The only guy who was stronger was using a half wave vertical...his 120 ft, tower. A properly constructed dipole at a proper height is a formidable antenna. A lot of hams are afraid of open wire because it requires a tuner....nonsense.....once you figure out what you're doing it's a piece of cake.

[@DaveJ-BCMA]

Great video. Thanks.

[@ElektroLUDIKITS]

As always, thanks for the Celcius, Kevin! ;)

[@markjacobsen302]

Just a handy idea for you there Kevin; in my little shack I put a small card up on the wall with a homemade chart for Fahrenheit to Celsius conversion at a glance.

[@viknumbers701]

K7VIK VIK I have been running a similar doublet fed open wire via 4:1 balun for many years and wet weather does not seem to do anything but need a slight change in tuner adjustment. 73s

[@mikesmithg0rfd356]

thank you for great video.

[@Liberty4Ever]

I wish I had a little more room to put up a doublet. Thanks for the great video.

[@Liberty4Ever]

@Alexej Svirid - Got a sling shot? Shoot a lead weight over a limb to pull a thin fishing line that can be used to pull a thicker line that can be used to hang your antenna. Weight the ends of line on each end of the doublet to tension the antenna. When the antenna stretches, it can be pulled down to shorten it without untying anything. The weighted lines can have tails that can be hanked when the antenna is in use and untied when the antenna is lowered for maintenance so the antenna can be hauled back up again. No ladders, no bucket truck or lifter, and no arborist skills.

[@jeffminnick5209]

Cool beans on Cape town...over qso'd with him as well Keep em coming Kevin 73 de WD8JM

[@chuck4050]

Great build and review Kevin, I have been using a doublet for about 3 years now and just love it. I have made contacts all over the world. I have gone thru the bands and written down where to tune for each band. You can probably get it to work on 6m also. Your 110" Dipole is the recommended length for a shortened Dipole by DX Engineering, I will post the info if it will let me. Good job and I may see you in Quarsite, Chuck. static.dxengineering.com/global/images/instructions/dxe-wa-ins-rev3.pdf

[@imahamjim]

Nice video Kevin i use same antenna no balance I use a old Johnson link coupled matchbox 73 Jim K1AZ

[@imahamjim]

Balance shut be balun

[@g0fvt]

Great to see that it is working well for you, doublets were far more popular in the past before coaxial cable came along and spoilt everything 😀

[@kelvin0mql]

Well dadgummit, the two trees which hold up my OCF 40m Wyndom Dipole are (according to Google Maps Sattelite View Measure Distance thingy-jobber) 113ft apart. Since getting the EFHW for 80m, I've almost never switched back to the OCF. Not that I love doing antenna projects in MN winter, but I'm going to change the OCF out for a doublet ASAP. Shouldn't be TOO difficult, given that I've already got nylon line in place that I'd used to string up the OCF. Will replace that with fresh stuff during the switch.

[@stevefoudray487]

This video has me interested in the doublet. T shirt weather is when the sun is shining, wind is not blowing, and at least 20F in western S.D. 73 KE0RKP

[@BrianJurkowski]

Love the videos, Kevin! Keep up the great work! If you don't mind me asking; at 10:42when he said "FCC" what was that 'pew' I heard, and saw across the spetrum analyzer? ...I'm guessing it's not phaser-fire from a nearby Storm Trooper.... :)

[@loughkb]

Those sweeping transmissions? I've been told they are ionosonde radar. Used by some organization to monitor ionospheric propagation I presume.

[@wa6gxq]

Kevin, enjoyed the video. I get so excited like you when i "score" a new country. 73 wa6gxq

[@reallybadaim118]

It's a great antenna.

[@larryoob8754]

Hi Kevin...... Great topic. I really like the doublet. I had a OCF for about 10 years and it was "OK". My current doublet is an inverted V, up 40' and 120'. I have read .... "put as much wire up as you can"...... Do you think there would be any measurable improvement extending to 140'? I tune with an Palstar HF Auto along with a 4:1 current balun. I have the room. Thanks in advance

[@loughkb]

More capture area, should translate into better sensitivity on RX. Just speculation though. I'm slightly confused though. You mention an off center fed antenna, which wouldn't be a doublet. The doublet is symmetrical, both legs of the antenna exactly the same length.

[@larryoob8754]

@@loughkb I'm using a 600ohm "true doublet" ...........Before the doublet.... I was using an OCF for about 10 years. Thanks for the reply

[@BlessedLaymanNC]

May I suggest that you compare antennas with weak signals. With strong signals, you won't notice some differences.

[@nk14zp]

My doublet fed with 300 ohm crap line beats the 160 inverted v coax fed it replaced. Doublet is also inverted v.

[@G0ogs]

In my experience as long as you can get 3/8 of a wave up there its should work well, ie 100ft top for 80m.

[@SpinStar1956]

Kevin, I use a 102-foot doublet nd it works fine on 80M; it would be interesting to see if you could tell a performance difference by making it a true 1/2-wave on 80M; also how it would differ from your 110-foot on the other bands as well. 73...

[@dougmatthew9987]

Great DX Kevin. You have my mind thinking how I can put up a doublet.. Does it matter how much coax I use to get to the 4:1 balen?

[@loughkb]

As short as possible. The coax will be the loss leader.

[@dougmatthew9987]

@@loughkb Hi Kevin. I already have 2 100ft of coaxs, one goes to a 130ft end fed wire that I use for digi modes. The other coax I'm going to connect to a 136ft HWEF for Phone. But after seeing the doublet I wounder if using a 4:1 at the coax to a doublet would be better. It will be an inverted V with the ends at 10ft and the center at 25ft. I've already built the 49:1 for the hwef but I can always switch it with the 9:1 on the current end fed. Enjoy your winter in the AZ desert. Merry Christmas.

[@jeff2424]

I've been using a doublet for years in my RV in the Sonoran desert. I have about 8 feet of RG-8/X from the 4:1 balun through the wall into my MFJ auto tuner. Works great on all bands 80-6 meters.

[@charlesholzschuh5551]

Try putting a matching transformer at the feed point between the antenna and the ladder line.

[@DuhBiggestDog]

There's no need for any transformer at the feed point of an antenna such as this. Putting a transformer at the feed point would greatly hamper the multiband capability of the antenna. Kevin's configuration is correct. The only addition he might want to make is to install a current choke where the coax attaches to his 4:1 balun. His antenna will almost always have high SWR on the feed line. And, as Kevin correctly points out, that is not a consideration when using a balanced transmission line. However, because of those high standing waves, there will be common mode current flowing on the outside of the coax braid and into the shack. And, it will be radiating RF into the shack. This will not be very noticeable at lower power levels. However, as the power level is increased , so will the radiation , and you may find electronics in the shack reacting strangely.

[@willgilliam9053]

Celsius to Fahrenheit is easy to calculate, Multiply Celsius by 1.8, then add 32 to cal-i-brate. Neat lil limerick

[@marciuschester3683]

Kevin, You're knowledge/experience on wire antenna's brings back memories of my mentor that is a silent key extra class amateur radio operator/retired brigadier general from the united states army/ former aide to president truman. He taught me alot about wire antenna's and always said if built correctly could break pileups without using an amplifier with a swr under 1.1. I still believe that theory. The best antenna's I have built are the vertical dipole/end fed half wave sloper/halfsquare/half delta loop/skywire loop/extended double zepp. My favorite of them all is the extended double zepp due to it having a 3db gain over a dipole. I built it for vertical polarization. When groundwave/skywave propagation conditions are good I'm able to qso with 98% of the operator's I call also without using a amplifier with a swr under 1.1. Keep up the good work and continue to stand out like a search light amongst candle's. 73

[@billwhite659]

Hey Kevin, Have you play'ed with the Half Square?

[@kevmscott]

I hope you don’t mind a question. I’m considering erecting a doublet antenna, 110ft long about 25ft off the ground and feed by 450 window line into a Balun and tuner. It will be a flat top. But about half of this antenna (1 leg) will be suspended above the roof of my house. About 6ft above the flat roof. Am I just setting myself up for disappointment? I’m afraid with on leg being so close to the structure, I will be creating unbalanced voltages across the legs and severely compromising the antennas performance. Thoughts. Suggestions?

[@loughkb]

I doubt it will affect the antenna too much, maybe a little. What is more concerning is the amount of noise you'll pick up from all the noise sources in your house. Also, if you run 100 watts or more, you're going to cause all kinds of RFI inside.

[@kevmscott]

Thanks Kevin

[@PatAutrey]

Quick question so are you using two separate 4:1 baluns The one in the tuner and the external one that you built at the same time?

[@loughkb]

No, only one is needed. The best case would be to bring the parallel feed right to the tuner's balun and eliminate the loss of even the short 50 ohm coax run.

[@ralph9987]

what tuna did you use? the inbuilt 7300 one?. what length would i need to cover 160m as well? thanks

[@loughkb]

Since the doublet has an inbuilt mis-match where the parallel feeder connects to the antenna wires, the impedances on the different bands will be all over the place with SWR often exceeding 3:1. The inbuilt tuner in the 7300 can't handle strong mis-matches and probably wouldn't have the range to work on all of the bands. I have an LDG Z-11 pro. It has no problem on all the bands.

[@charlesschindler1971]

Kool!.....Kevin . ✌️out!

[@jeffreyeide7512]

Yo Kevin: Great video & catch with the S African! Especially at 30/40 watts! How again is a doublet different from a dipole? Their nearly the same? I know you'll treasure that ZS card in your shack. Did you try 17 mtrs & find the band open? Best of 73's & carry on! de seeker/Jeff WA7LFP

[@DuhBiggestDog]

A dipole is a half wave resonant antenna at a particular frequency. Kevin's antenna is a non resonant antenna. For example, if Kevin lengthened his antenna a bit, it would become a resonant dipole on some frequency on 80M. However, when he uses it on other bands it is functioning as a non resonant antenna. The feed line does not dictate whether an antenna is a dipole, or not. It is the length of the antenna matters.

[@renejrgensen9865]

I will build this antenna. Between two poles. ANd on the one pole I will mount a commersial vertical which will then get into a very high hight. It could be nice if you made the experiment if there are any difference when setting it horisontal or as an inverted V. The high point the same in both cases. Any difference in the ability to reach DX??

[@loughkb]

I usually use it in an inverted V configuration due to the logistics of putting it up in the desert. Dipoles are a *bit* more omni-directional when set up as an inverted V.

[@BusDriverRFI]

Your vertical antenna should work DX very well.

[@M0JBM]

I wish I had the room to build 1

[@Oldhogleg]

Cool contact! Question; you say you're using a balun. But isn't a balun used to match balanced to unbalanced, yet since you're using a ladder line you only need to match the impedance of balanced to balanced, meaning you don't need a balun, but just a simple balanced transformer?

[@messupfreq550]

I believe he uses coax to pass through the camper wall, otherwise he would have a tougher through wall to directly connect the window line. Also, I really love his "let's try this attitude.." however I did some digging around and actually a 1:1 is recommended for this antenna type rather than the 4:1. Here are the counter-intuitive details: www.karinya.net/g3txq/tuner_balun/ In all honesty if I was homebrewing this antenna I would have used the 4:1 as well.

[@Oldhogleg]

@@messupfreq550 Thanks for the link! 👍

[@Oldhogleg]

@@messupfreq550 I Assume the preferred current balun is in reference to an auto-transformer as apposed to separate primary and secondary?

[@messupfreq550]

Oldhogleg Not sure the type was mentioned, however, most commercial made 4:1 are voltage baluns and the idea is to use a current balun to keep the window line currents matched. Does the mismatch cause reflections, yes absolutely, however as a multiband antenna the impedance is going to flop around anyway and a tuner is the only convenient way to adjust for that eventuality.

[@Oldhogleg]

@@messupfreq550 It mentioned current balun like you said, just not clear on the difference in construction/design that makes it either a voltage or a current balun?

[@kissingbanditt]

Do you have a link on where i can buy a doublet? I live in Toronto and we have a radio store named radioworld but not sure what im looking for. You need a 4:1 balun or a 9:1? Thank you kindly.

[@danl2825]

Might look here: www.trueladderline.com/

[@g0fvt]

Theo T to be honest a 1:1 common mode choke is generally fine, and better for the ATU. There is a build video, why would you want to buy something that is just a few bits of wire?

[@BrianEsche]

Theo, in looking at Radioworld's web site, they do offer the MFJ-1777 pre-built doublet. However, a similar (or better) antenna can be constructed from some wire, window line and center/end insulators (and you'll likely spend less money). If you prefer to buy a kit of reasonably high quality parts, DX Engineering here in the US offers various lengths and the prices seem to be reasonable. Below is a link to those kits. Disclaimer: I have no connection to either retailer but I have purchased two of the doublet kits from DXE (along with some other wire antenna parts) and have been pleased with their quality and value. www.dxengineering.com/search/department/antennas/section/wire-antennas-and-parts/product-line/dx-engineering-multi-band-dipole-antennas?autoview=SKU&N=section%3Awire-antennas-and-parts&sortby=Default&sortorder=Ascending

[@kissingbanditt]

Brian Esche ok i will try to make it. So i already have the wire. I do not have the feed line though. Or ladder line. Do they come in different impedance ? If so which one do i need to buy and how long should it be? I will also need a 1:1 balun. Any recommendations? Thanks very much for looking and posting a link for me.

[@BrianEsche]

@@kissingbanditt Radioworld or other retailers in Canada may stock balanced feedline in bulk from which you can purchase the desired length. It will generally come in 300, 450 or 600 ohm impedances. 450 ohm ladder line is the most common but in this application the impedance really doesn't matter. The length isn't critical but a rule of thumb is to make it an odd multiple of 1/8 wavelength on the lowest band you plan to use to allow the greatest range for the tuner. The ideal situation would be to run the ladder line all the way to your tuner (if it has a balanced line input). Doing so would eliminate the need for a balun. If your tuner only supports coaxial input then a 1:1 balun would be your best bet (Radioworld stocks several baluns including the LDG 1:1 model which I've used successfully in the past). It's also possible to construct your own balun with a minimum of parts if you prefer to do so. If you do use a balun, use the shortest possible amount of coax between in and your tuner to keep the losses to a minimum.

[@rossbassette7518]

Kevin, Appended your callsign, what does "7" signify?

[@jmriello]

He is a 9 call working in 7 land.

[@Gabagabe1]

To signify He's in the 7 call district as opposed to the 9 district one would assume from the 9 in his call sign

[@roydickinson4808]

The Doublet can be tuned without a tuner by using varying lengths of feed line. See w5dxp.com. (no tuner antenna) My 135 foot doublet was tuned at 7.2 Mgz and I use it with about 85 feet of 450 ohm window line. Start with 100 feet 450 feed line and trim it until SWR is good on 7.2 Mgz and you should be good. I use this antenna with a tuner with built in balun on all HF bands. 73, N5SWE

[@roydickinson4808]

The w5dxp.com site is no longer available. He used switches to switch in 1 foot, 2 foot, 4 foot, 8 foot, and 16 foot sections of 450 ohm widow line to tune the doublet antenna with no tuner. I use a tuner but if you have trouble tuning this antenna, remember it is tuned by length of window line feeding it. Check "Double Extended Zep" that is 5/8 wave length long. N5SWE

[@USXPOP]

Insanely jealous of you and all the desert to hang antennas. Maybe someday when I win the big lotto...

[@sparky42]

I built one . 135 ft. of brand new flex strand copper wire and brand new 450 ohm window line of good quality . I brought the feed down to a brand new 4:1 palstar balun and out the other end with 2 feet of a good quality coax into my MFJ 962 d tuner and nothing ! I can't imagine what I did wrong . also tried a 1:1 and still had a hard time tuning everywhere . I kept the window line away from all metallic objects etc. still no luck . I would like to try it again sometime . It still befuddles me . I wish I was able to bring the 450 right to the tuner but there is no way . Show a picture of the antenna next time , Tnx. de ka3fad

[@loughkb]

The balun should be a current type and not a voltage type. I did a video not too long ago on winding a 4:1. That's the design I'm using and it's working very well. And pictures are included on the build video that's link in the description.

[@roydickinson4808]

The Doublet can be tuned without a tuner by using varying lengths of feed line. See w5dxp.com. (no tuner antenna) My 135 foot doublet was tuned at 7.2 Mgz and I use it with about 85 feet of 450 ohm window line. Start with 100 feet 450 feed line and trim it until SWR is good on 7.2 Mgz and you should be good. I use this antenna with a tuner with built in balun on all HF bands. 73, N5SWE

[@anthonycosta1776]

You never mentioned length of doublet and feeder length....oh sorry. You did lol. 👍. At 110 feet it's going to tune 40 and 20 with easy as the impedance is going to be excellent. If you do the basic 135 foot antenna your tuner will be hard to tune and losses will be high even with ladder line. Heat in tuner. So 110 feet is the answer.

[@imahamjim]

Balance should be balun

[@fredmetcalf]

That law in Arizona has to be really hard on your lawnmower.....? ? ?