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Re: [TowerTalk] Best way to mount two LPDA on single mast

To: towertalk@contesting.com, fourstar4sale@yahoo.ie
Subject: Re: [TowerTalk] Best way to mount two LPDA on single mast
From: K7LXC@aol.com
Date: Mon, 9 Sep 2013 14:43:32 -0400 (EDT)
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
>  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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