[TowerTalk] Stackign yagi's

[Cam and Juli Hedrick]

Hi all, I'm raising my tower and planning to stack a 20m monobander I built
with a Telrex TB4EC about 8' feet above it.  I was told that interaction
will be a problem, so I was just thinking that I could retune the TB4EC 20m
elements for 17 meters.  Will this still present an interaction problem?  I
could move the 15 meter monobander from another tower that has my 2 elements
on 40m, but that will mean hiring a crane and I'd like to avoid that.  All
help greatly appreciated as work commences today.
Thanks
Cam Hedrick
WA4JKW