> I am putting up an 80' self supporting tower (AN Wireless HDD-80). I
will be using 2" chrome moly mast with ~ 10 ft of mast above the top of the
tower.? To this mast I am planning on mounting a?7-30Mhz, 14 element LPDA
and above it approx. at the top (8' separation) a 50-1300 MHz LPDA both from
Tennadyne.
> Should I lift the antennas already mounted on the mast and lower the
entire assembly into the tower and rotator, or should I have the mast already
attached to the rotator and lift (by crane) the antennas and mount them to
the mast?
Congratulations on your new system. Be sure to hire a concrete
contractor to install the rebar cage and pour the concrete. In spite of
installing
dozens of towers, I found their drawings difficult to interpret.
And if someone could tell me why AN Wireless towers require about 2.5
times the amount of concrete for a pretty straightforward installation, I'd
appreciate it. (File under "stupid base designs" alongside the Trylon
Titan drawings?)
> If the second option? is the chosen method how do I attach the upper
antenna (I am tall but not ten feet tall)?? Do I need to drill into the mast
and place steps into it??
In this case you're trying to do at least 2 things - install the
mast and install the antennas. I've found the hard way that trying to do 2
things at once always leads to problems and likely re-doing of one thing or
another. I'd recommend installing the mast and then installing the
antennas. Use the crane to install the lower antenna first so that it'll be
out of
the way of the upper antenna when the crane lowers the top antenna.
If you try to install the mast with antennas attached, a big
problem will be de-rigging the mast - you'll likely have a sling or two out of
reach.
> Finally, are there any other approaches I should be considering?
I endorse using a crane. You should get it with a man-basket. That
way the crane can lift you and the loads up and down and you don't have to
do much tower climbing.
Be sure that your antennas have been tested and have pigtails from
the feedpoint to the mast (and I'd allow several extra feet to make them
easier to work with). Then you can attach the feedline from the ground with
a barrel connector and you'll be good to go. Be sure to follow good
weatherproofing techniques on all coax joints and that should about do it.
Temporary mast steps are easy to fabricate and use. The biggest
problem is using them to actually climb the mast. This is a major challenge
for most people and it's a rare person that can actually do it. Use the
crane - it's faster, easier and you won't have to climb the mast!
Cheers & GL,
Steve K7LXC
TOWER TECH -
Professional tower services for amateurs
PS - All of this - and much more - is discussed in my book UP THE TOWER -
The Complete Guide To Tower Construction - available from
championradio.com. I made all the mistakes so you don't have to - HI.
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