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

[Joe Subich, W4TV]

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