Call me henpecked but the XYL will not let me put my LM354HD unless it goes
> in the same spot as my HyTower, which works on 20, 40 & 75 (no stingers for
> the other bands).
Given your restrictions (which I will accept as a given, though I expect
someone to come along any second and tell you to get a divorce), I would say
that you DO have to worry about interaction between the HyTower and the
tower but not all hope is lost.
You can potentially *measure* the current in the tower after you put it up
and use "resonant breakers" to insert, basically, a trap in the tower tuned
to 40m and 80m if you find that currents on those bands are substantial
One way to do it is to build a conductor loop, one side of which is the
tower, and the other three sides of which are made of heavy wire that goes
out, drops down and comes back to the tower. This is an inductor. You
resonate that with a capacitor (or a pair of switched ones) and that tower
section becomes a high impedance parallel resonant circuit.
Picture is worth a thousand, so here you go:
http://www.w8ji.com/detuning_towers.htm
As far as the yagi? It won't care one bit that the Hy Tower is there, in my
opinion, just because of the cross polarization although again. a current
meter might be of help. If anything, you could get a little bit of current
induced in the HyTower when the high voltage tips of the yagi get close to
the tip of the HyTower. If you're getting significant current at the base of
the HyTower when you transmit on the yagi you might consider trying
different options of terminating the HyTower antenna at the base, shorting
it or leaving it open or inserting another load, etc.
I have a 20m Moxon Rectangle whose closest approach is only about 5 feet
from my 60 foot wire vertical, and I find that there is a *slight* SWR
change on the Moxon and maybe a *slight* change in signals off the back
depending on which band I select on the matching network for the 60 foot
wire.
All in all, I think it'll take some work, but there's hope.
73
Dan
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