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Multi-Band Dipole Tuning?




 
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Author Topic: Multi-Band Dipole Tuning?  (Read 4473 times)
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K2AWA
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« on: March 23, 2014, 09:41:24 AM »

I recently installed a multiband dipole antenna similar to the OCF Buckmaster series. I used a Balun Design 4:1 balun, 13 ga. insulated wire and legs are about 45 and 90 feet.

The antenna needs minor tweeking for SWR and needs to be shortened. My question is, since the wire is insulated, I probably won't get a correct reading if I fold it over tightly over itself before the actual trimming? 
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W2VW
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« Reply #1 on: March 23, 2014, 09:53:35 AM »

That would be a problem is the end was folded at 90 degrees or more toward straight.

Folding the wire back around itself makes it work as if the length ended right at the fold as desired.

This is nice in case too much wire is removed.

Hope this makes sense.
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WD5JKO
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WD5JKO


« Reply #2 on: March 23, 2014, 11:00:42 AM »



If the balun is overbuilt about 10X for the power you are running, and if your coax is low loss type, then just run the thing through a good tuner. Forget about trimming the line SWR since the SWR dips will vary band to band..fixing the swr on one band will screw it up on others.

I use an Array Solutions OCF dipole. It has a massive balun in a sealed box. With 50' of LMR400 coax, and a Heathkit 2060A tuner, I can run 80-6M. I do pretty well on those bands too. This antenna has no SWR dip for 15M, so the line SWR is pretty high there. Still I get out quite well on that band, and the setup takes 200 watts AM or 1KW PEP.

Jim
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n1uvi
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« Reply #3 on: March 24, 2014, 08:02:12 AM »

if you have a tuner
an OCF Dipole fed with coax will not perform as well as a single band dipole fed with ladder line
on any band

the best mufti band antenna in my book
is a center fed 80 meter dipole fed with ladder line and a tuner

don't bother shortening the OCF, it will never be right on any band no mater what you do
it is an unbalanced antenna, too much reactance, never resonant


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