[TowerTalk] Tuned Feeders

[Bill Coleman AA4LR]

On 9/26/97 10:33 AM, Tom Osborne at w7why@mail.coos.or.us wrote:

>I'm in the midst of putting up an antenna for WARC bands.  I'm making a 
>130 foot dipole with tuned feeders.  In reading about the feedline it 
>stated that the foam 300 ohm solid ribbon is not that good to use 
>because when it gets wet the SWR changes.  Is that a problem other than 
>the fact that I may have to adjust the tuner a bit to get the SWR back 
>down.  Will it detract from the operation of the antenna?  Thanks

All that foam dielectrc introduces loss, which is exactly what you don't 
want when using tuned feeders. So, instead of the 300 ohm ribbon, try 
finding some 450 ohm ladder line instead. This has insulation in little 
"windows" about 1" wide and 2.5" long. The less insulation, the better. 
Get the kind with stranded conductors, not solid, as the solid conductors 
may break as it sways in the wind.

Even better would be open wire line, if you could find it. Radio Shack 
used to carry this stuff about 20 years ago for use with television 
antennas, but no more. Or you can make your own.



Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@radio.org
Quote: "Not in a thousand years will man ever fly!"
            -- Wilbur Wright, 1901


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