Since you already have a stacked pair of TH7's,
your best bet would be another tribander on another tower.
I would not advise adding another beam at 25 ft but
instead recommend a second tower between 35 and 40 ft.
This height is optimum for the higher angles supported by
the ionosphere during daytime conditions and is still useful
at night, especially to Africa on 20M. By having a second
(short) tower, you will benefit from the ability to rotate the
second antenna as needed. For a short tower, you can
bring the guys in closer than 80% that is recommended
for tall towers since there is only one set of guys pulling
down on the tower (Rohn 25 can withstand 15000 lbs
of vertical load).
Another possibility might be a rotary dipole for 10/15/20
spaced 10 ft. above the top TH7 and parallel to the boom.
Or, some fixed dipoles at 40 ft in trees or on other supports.
de Tom N4KG
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