Author Topic: The DOUBLET ANTENNA, another ALL BAND antenna ,needs antenna tuner  (Read 2365 times)

Offline Carl

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  Had another antenna party with Jeff and Brandi got to exercise and play ball till her tongue was dragging,then she played some more.

  The DOUBLET is the name given,years ago,to a non-resonant DIPOLE or INVERTED "V" antenna that ,because it is non-resonant,can be used with an antenna tuner on all or most Ham bands. The DOUBLET can be fed with ladder-line or coax and this test antenna was fed RF with coax to a 4 to 1 balun and each arm of the antenna is 51 feet long....though as I had a roll of 50 feet of 14 gauge speaker wire....we made a DOUBLET that was 50 feet per element and used a speaker tripod to raise the center feedpoint to about 15 feet on a painters pole that was handy for support and managed to fit the antenna in my small yard in the shape of an "L" and the ends of each 50 foot long 'leg' were tied to my 4 foot tall cyclone fence.

  Not the best location or position for an antenna as it was barely taller than my house.I set about connecting the 50 foot long length of coax to my IC737 radio with it's 3 to one ratio capable tuner. The bands really came alive as there was a 'contest' going on (rare is the weekend that there isn't a contest) and people were hammering each other for a contact number as if it proves some ability in a station and operator that is more subject to the whims of propagation than operator skill or station capability...beyond operator stamina.

  Worked stations on 80 meters (NVIS will work during the day on 80 meters) ,40 meters ,20 meters and tuned easily all bands 160 through 12 meters ...but had troubles with 10 meters as the radio's tuner with only 3 too 1 ratio tuning while the LDG tried later ran 10 and 6 meters ,along with all the rest of the frequencies. The low antenna ,placed is less that optimum height and orientation showed how EASY it is to be heard on the active Ham bands with simple equipment.

  The 50 foot DOUBLET was easy to make with it's 50 feet of wire on each leg fed by the 4 to 1 balun and worked well with even the limited capability of the internal tuner,I was surprised,and am already thinking of a way to incorporate one into my 60 X 60 back yard.  The Ham on the run might find it not too tough to install with a water bottle at each end ,tossed over a tree limb but don't forget to support your coax at least each 10 feet so it does not get damaged or stretched beyond design limits as your coax is very important and must be protected.

  The fifty or 51 foot DOUBLET is a winner ,especially as an all band base antenna though it takes little time to install for a weekend stop and will be well worth the added capability of the balanced,non-resonate ,omni-directional antenna.PLEASE test one and post results here as antennas of the past bring your radio hobby back to life.

Offline Smurf Hunter

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Re: The DOUBLET ANTENNA, another ALL BAND antenna ,needs antenna tuner
« Reply #1 on: November 19, 2017, 08:43:54 AM »
What are the advantages of using ladder AFTER the balun as some instructions show?

I currently use a 4:1 to feed a few pairs of resonant dipole (fan) wires in my attic.  All the wires are joined directly at the balun.  It would be trivial to just replace with 50/51 feet lengths and see what happens.

Offline Carl

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Re: The DOUBLET ANTENNA, another ALL BAND antenna ,needs antenna tuner
« Reply #2 on: November 19, 2017, 09:08:54 AM »
What are the advantages of using ladder AFTER the balun as some instructions show?

I currently use a 4:1 to feed a few pairs of resonant dipole (fan) wires in my attic.  All the wires are joined directly at the balun.  It would be trivial to just replace with 50/51 feet lengths and see what happens.

Ladder line is often used to reduce coax loss due to high SWR...which has been proven to actually be minimal losses though the mouth to ear advice continues to cause Hams to work overly hard for a watt or two.Link is for PDF from my Google drive to explain or confuse the non resonant antenna and coax feedline due to SWR issues. I find ladder line is a much better antenna than a feedline and in case someone looks ...the 50 to 51 foot DOUBLET is indeed very close to the G5RV antenna ,though with convenient coax feed.Were I a low power station or outdoors/portable operation...I might use 34 feet of ladder line to save about 2 to 4 % loss....But I do thing the EASY WAY as I would rather operate than spend my time adjusting and supporting my station.Read about feed line SWR losses at bottom of page 1....

https://drive.google.com/open?id=1r9g-aX1DnaFoN6X1G6oQY6mAcc7eW1hX

Offline Carl

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Re: The DOUBLET ANTENNA, another ALL BAND antenna ,needs antenna tuner
« Reply #3 on: November 24, 2017, 09:53:39 AM »
50 foot long X 2 doublet use report

  My local Ham in training took the opportunity to Ham it up this week and moved his RV camp trailer to a local park on a lake just North of town to Holiday and operate his portable Ham station (FT857D Yaesu with LDG automatcher) and even stopped by to share some pulled pork and fried turkey with fixins with me and Brandi. The food was GREAT and Brandi got to play ball a few minutes....a plan was formed...and Jeff ran a test of the antenna after sunset when 30-10 meters had poor propagation, Below are links to his 2 hour results by band and his logs that show he had great results under poor conditions with the antenna and notes that 160 did NOT tune at the temporary location about 25 feet up in the trees with 14 gauge speaker wire split for the 'inverted "V" non resonant antenna.His report...."GOOD"

NOTE that he did 'work' stations all about the US,Western Canada,Way into South america and North East into Nova Scotia. UNDER 200 miles to about 5,000 miles on the 50 foot DOUBLET and his FT857 and tuner  at 20 to 25 watts!!!....Great test JEFF.

https://drive.google.com/open?id=1kPWgsUCqc579KLiiAVbRFlqFv606xRGZ
« Last Edit: November 24, 2017, 10:12:29 AM by Carl »

Offline Smurf Hunter

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Re: The DOUBLET ANTENNA, another ALL BAND antenna ,needs antenna tuner
« Reply #4 on: November 24, 2017, 10:15:46 AM »
Excellent work! 

Oddly enough, LA is one of the few states I've not made an FT-8 contact with.  We should be able to remedy this :)


Offline Carl

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Re: The DOUBLET ANTENNA, another ALL BAND antenna ,needs antenna tuner
« Reply #5 on: November 24, 2017, 10:32:19 AM »
  I am sure Jeff will oblige as he is the Ham you and I spoke with on his way to the campground ,with you on ECHOLINK yesterday. You anf Jeff both wished me happy Thanksgiving....not my girlfriend or even my son took time to call...my Ham family is great!