I have a 135' long doublet, 45' in the air fed with 450 ohm ladderline. It
tunes fine and works well through an MFJ tuner on all bands up to 21MHz.
Above 21MHz I have a very difficult time tuning the antenna to get any SWR
below 3:1. I cut 6' off the feedline when it was finally dressed into my
shack and that made it worse. I have now reinstalled the extra 6' and that
is better for tuning, but not yet perfect. I guess I'll just have to keep
adding or subtracting small amounts of feedline to get it right?

Yes, try adding some feedline.

I have a ~120' doublet center fed with ladderline. No problem matching it
on 80/40/20/15/10 with a Johnson Matchbox. But I did have to change the
feedline length from what I started with.

Torsten
N4OGW