I have a MUCH MUCH less messy solution.
Is the dipole (center fed) 130 ft (80m) or 66 ft (40m) or 33 ft (20m)?
Center feds will work on the 3rd harmonic, so a 40m can also tune to 15m.
So¡. try this ¡ for $1.
Put a small inductor (say 5 turns of wire 1 inch diam) across the dipole where it attached to the coax.
If you have a 1:1 balun, leave it in place.
This will RAISE the input impedance (just like the method to couple a mobile whip to 50 ohm coax.
You MAY have to then shorten the wire a bit at each end ( try 1 ft at first) to get it back to the resonant freq you want.
I often do this on a very low 80m dipole (130 ft) when it is low to the ground.
Impedance at 20 ft above gnd is often about 20 ohms.
But if you try to change the impedance by changing the LENGTH of your coax, the SWR will not change.
You will only move the impedance around the Smith Chart, so you may get a higher impedance than 50 ohms,
but the SWR will still not change.
If on 80m you may need more inductance across the dipole input¡. so try 10 turns of wire, 1 inch diameter.
Eventually the inductance in parallel with the dipole will raise the impedance to where the 50 ohm coax will match a bit better.
Let us know if that works.
Messing with 1:2 baluns is kind of silly and expensive when a simple inductor across the input will work.
de k3eui. Barry
Barry K3EUI