No subject

[michael watts]

Hi Steve, thanks for the reply.

I have for years now (8 I think) had the existing
setup.  I have an LM470 motorized crank up as you do. 
I have a 22' chromalloy mast with about 2 or 3 feet in
the tower.  On top of the mast I have a 5 el 15 meter
yagi (Hygain 155BA), then in the middel I have a 5 el
20 m yagi (Hygain 205BA), and on the bottom, just
above the thrust bearing, I have a 3 el 40 m yagi
(KLM).  The tower is rated at 16 sq ft and I have 30
sq ft on it.  I deal with this by never leaving it up
while unattended and lowering it part way when the
wind blows.  If the wind kicks up above about 20 mph,
I lower the tower some.  

This setup has given no problems.  I have not spent
any time fixing things, nothing has broken.  However,
there are some things I dislike about it.  First and
foremost, the rotor is an HDR300 and it does not fit
well in this tower.  It is not exactly centered under
the thrust bearing.  It could not be located further
down inside the tower - in order to get more mast in
the tower - because it protrudes thru the outside
envelope of the top tower section.  If it were mounted
lower, it would prevent the sections from telescoping.

Since the rotor is off center the mast is tilted in
one direction.  I have never measured this tilt, but I
would guess it is 2-4 degrees.  Maybe more.  So the
long lever arm and this tilt put stress on both the
rotor and the mast.  Even though it has not been a
problem over the last 8 years, I still worry over it.

I am going to disassemble it all (but with the tower
upright) and rework the top of the tower so the rotor
is centered.  Since I will have it all apart, I
thought I might as well install the strongest mast I
can get.

But this brings us to the tradeoff.  Weight.  As you
point out, the tower is rated for 300 pounds and it is
load to just about that weight now.  If I put a
heavier mast in, it will be more overloaded.  Which
might not stop me, but I don't like it.

The use of the tower is changing.  I am installing a
block at the top of the mast and an electric winch at
the bottom.  I am permanently mounting brackets on
each antenna spaced apart from and centered on the
Center of Gravity.  Then, using sailboat hardware such
as snap shackles, I will attach the halyard and winch
antennas up and down quickly.  My goal is to get to
the point where I can dismount an antenna and move it
to the antenna storage area in less than an hour,
almost entirely (except for carrying the antenna away)
do this alone.

For each contest I will select a band to operate (I
have decided to forgo single op all band efforts in
favor of single band efforts - that way I get a little
sleep) and select an optimum set of antennas.  Then I
will remove my "normal" (DX) antennas (which cover all
bands) and install the single band antennas.  After
the contest, I will reverse the process and reinstall
the DX antennas.  For this upcoming WPX CW contest, I
will install two Force 12 Magnum 715 7 el 15 meter
yagis - one at the top of the mast and one just above
the thrust bearing.

When I put it all back together for DX work, there
will be a new beam on top of the mast and it will be 2
sq ft larger and a little heavier (it will weigh 48
pounds) than the 15 m monobander that has been
residing there.  This all makes me think of a stronger
mast, if possible.
  
Any thoughts?

Thanks!
Mike wy6k
--- K2we@aol.com wrote:
> 
> I too must ask what antennas are you going to
> install and what kind of a 
> tower will this go on. 


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