[Elecraft] feeding a half-wave dipole with ladder line

[Walter Underwood]

Are you sure your ladder line is 200-300 Ω? My calculations say that 12 AWG conductors 12 inches apart makes 680 Ω line.

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Oct 28, 2021, at 2:47 PM, Joe Subich, W4TV <lists at subich.com> wrote:
> 
> 
> Your 130' dipole will be damn near impossible to feed on 40 meters as
> the center is very high impedance.  You would be better served to
> hang a parallel dipole (33' per side) under the 65' wires and use
> RG213/RG8 for the vertical section.
> 
> The additional 33' wires will give you marginally more top loading
> and the coax will work just as well for the vertical element since
> you are shorting it top and bottom.  While you're at it, push the
> feeedpoint up to 50 feet ... more vertical for 160/630m and better
> performance for the dipole on 80/40.
> 
> 73,
> 
>   ... Joe, W4TV
> 
> 
> On 2021-10-28 5:23 PM, Ed Cole wrote:
>> I am redesigning my 40/80/160/630m antennas.
>> A year ago the tower I was supporting my 630m Invert-L was damaged by wind and taken down.  Replacement tower is shorter so not suitable end wire support for HF antenna.
>> I decided to repurpose my 80/40m dual dipole into a based-loaded 40-foot vertical using the 80 & 40m wires for top hat loading on 160/630m.  To do that I purpose to run 40-foot of ladder-line vertical and either load the bottom using a balun for 80/40m or short the ladder line for the loaded vertical.
>> http://www.kl7uw.com/630mTee.jpg
>> My question is what balun to use for 80/40m. ladder line is 200-300 ohm whereas the dipoles are near 50-ohm.  Should I use a 9:1 balun or would my original 1:1 balun work?  Tuners will be in the shack (KXAT at 100w; Drake MN-2000 at 1200w).  RG-13 coax to base of ladder-line.
>> I have a couple vac-relays to short the ladder-line and connect the loading coil for 160/630m.
>> Thanks, Ed - KL7UW
> 
> 
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