I am extremely happy to let you guys know that I have completed the building
of my 45 meters high rotating tower.
It has been a huge project for me. You can see the first pictures at:
http://www.lhv.ee/images/files/es5tv.htm
It carries 2 times 3 elements 40m stack at 42 and 22 meters heights
and 4 tribanders stacked at 45, 36, 27 and 18 meters. 40m beams are full
size with 12 booms and tribanders have 10 elements at 7.6 meter booms. The
configuration is carefully selected and modelled by me and I am convinced
that the 9 meter stacking distance is perfect for the tribanders. It gives
almost maximum results compared to stacking equal 3 element yagis with
optimum spacing on 15 and 20 and 4 element yagis at 10m.
I have not yet connected the tribanders to stack but 40m stack is 100%
operational. I can switch upper-lower-both. I was expecting a good stacking
gain although the height of the antennas is not so great but the result
surpassed my wildest hopes!
The stack is constantly getting more than 10db better results from DX
stations than upper antenna and lower antenna is the last. Incredible! You
have to hear it to believe it! Even for EU stations stack seems to be the
best usually. I am quite convinced I get much better performance from the
stack than I could have from big 4 element yagi at top plus I can switch the
antennas. The pattern of the stack is also excellent. The real life tests
show incredibly good F/R and F/S as computer models predicted. Often I can
hear the local stations 59 to the back or side of both single antennas but
they are gone to noise with stack!!
I can't wait to see the stack effect of those 4 tribanders. Antennas are
made by Finnish Antenna. I have rope fully in all elements. The upper halves
of the guy wires are from nonconductive Dyneema rope to avoid any
interference. Models show that there is no bad interference to tribanders
(especially to 15m) from 40m Yagis. The whole tower makes a full turn with 1
minute and 40 seconds. Upper tribander is at a 3.5 meter long mast of 80cm
diam tube.
I will give the 40m stack the first real test in WPX CW 40m monoband already
this weekend. I hope to hear you all!
73 for now
tonno
es5tv
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