[TowerTalk] 40M Yagi & 20M Yagi Interaction

[Bill Kantz]

I have a Hy-gain 2 el 40M @ 54' and a Hy-gain 3 el 20M @ 44' stacked. 40
is Ok but the center frequency of the 20 has moved from 14.1 to 13.9. I
tried a 90 degree offset and it got worse the center frequency moved to
13.8.
 
Any Ideas?
 
73,
Bill N2VZ