[TowerTalk] Stacking

[Michael Harris]

G'day,

I'm sure there will be some useful opinions on the following:

I currently run a 5 element 18-30MHz log.  The elements are insulated from 
the single boom and fed with transposed aluminium strip feeders.  No 
problem taping the coax feeder to the boom and I choke it with a ferrite 
1:1 ballun at the feed.  Anyway that really isn't the question.

I'm thinking of installing a 3 el 20M monobander on the tower and was 
wondering what the minimum vertical spacing between the two beams needs to 
be to avoid disastrous effects between the two.

There doesn't seem to be too much on that subject in the literature that I 
have.  Plenty info on stacking identical beams for gain but nothing on 
Christmas tree stacking of dissimilar beams.

Also regarding my previous post about my 30M vertical with two opposed 
gull wing radials.  I'm not on the beach, 50 metres back from the harbour 
so the near field sees turf, 40cm top soil, thereafter clay.  The coax 
from the solenoid coil choke goes straight down into some buried optical 
fibre cable sub-duct and back to the house.  There are some interesting 
comments and solutions to feeder radiation problems in Moxon's book.

Regards,

Mike VP8NO