I built the 15/10/6/2 fan last fall in the basement. Fine tuned it then dragged it to the top of the hill and put it up and when it was lit up it behaved exactly like it did in the basement. Based on this I tried the same approach with the 80/40/20 fan and set it up just outside the house a few feet above the ground. When I strung the antenna up the tuning changed dramatically much to my surprise.
Below is the 80/40/20 fan dipole after if was strung up at its operating position BEFORE it was tuned.
Below is the 80/40/20 fan dipole after if was strung up at its operating position AFTER it was tuned. Might I add it took hours and multiple trips up and down the hill.
Played around the next day a bit more and ended up with....
LESSON LEARNED as I moved the antenna up and down the impedance changed and the 1:1 match was skewd +/- 150 KHz.