[TowerTalk] Any Installation Tips For Trylon T400 Tower Installation?

[K7LXC@aol.com]

In a message dated 06/04/2000 12:42:48 PM Pacific Daylight Time, 
kg0us@swbell.net writes:

> The manufacturer claims that the section bolts only need to be tightened
>  to 6 ft-lbs of torque. This is probably not a problem since the bolts
>  use lock washers but will the bolts become lose over time?
>  
      No, not if tightened to the aforementioned spec. The diagonal brace 
nuts have captured washers on them and the leg joint nuts use a split washer 
so no sweat all the way around. 
 
      That's 'loose' although I sure you can lose them as well.
>  
>  We are planning on using a 20' long mast with more than half extending
>  out the top of the tower.  We are using a Yaesu G800SDX rotator.  We
>  plan on putting up a Force 12 C3S just above the top of the tower, then
>  a three element 10 meter mono band, a 10 element 2 meter beam, and  a
>  Cushcraft AR270 5 element 2 meter / 70cm beam close to the very top of
>  the mast. 

     Huh? A C3 that has 10M PLUS a 10M monobander? Wouldn't do it, 
destructive interaction is sure to occur. What's your reason for wanting to 
install both antennas?

      There's nothing wrong (or worse) than using just the C3. I'd get the 
C3E with the additional 10M element to maximize performance and skip the 
monobander. 

> The Yaesu rotator does not look very heavy duty in
>  construction from the outside.  Will one Rohn thrust bearing be enough?
>  
     Yes, but you don't even really need it - the rotator is fully capable of 
handling this moderate vertical load. 
>  
>  Do you have any tips or tricks as far as leveling towers with tapered
>  sections? 

      You need to drop a plumb line through the middle of the tower with a 
weight on the end. Sight through a tower face and line the plumbline up on 
the EDGE of the opposite leg. The leg edge is the only thing that's really 
plumb on the whole section. 

     Here's the base installation sequence:
1.  Get the backhoe in to dig the hole.
2.  While he's digging, build the rebar cage.
3.  When the hole is ready, have the backhoe lift the rebar cage into the 
hole (it'll weigh about 300 pounds so it's much easier to have him do it).
4.  Install the wood forms for the top of the base that is above grade. 
5.  Have the backhoe lift the bottom section with concrete stubs into the 
hole. This assembly weighs over 300 pounds too. Tie the concrete stub legs to 
the rebar cage at a height such that the bolts are above the top of the form. 

> Is it necessary to temporarily guy the bottom section in
>  place before pouring concrete?
>  
6.  Attach a comealong (cable puller) to each leg and a temporary ground 
anchor. Then you can pull the tower in different directions until it's plumb 
using your aforementioned internal plumbline. 
7.  Call the concrete truck and start chuting. Check the plumb a couple of 
times. Also rent a concrete vibrator to help spread the mud around. 

      I left some steps out (call the building inspector, etc.) but you'll 
recognize them. 

>  Tom is considering running his coax cables inside some plastic conduit
>  and then mounting the conduit inside one of the T400 legs.  Is this a
>  good idea?  I thought it might add to the wind load and also make it
>  difficult to remove a bad cable if one should go bad a few years down
>  the road.

     Why bother? Running cables inside a tower and through conduit are pains 
in the butt so I avoid them at all cost. One of the only good reasons for 
cables inside the tower is for lightning protection (the tower acts as a 
Faraday shield) but I don't know why you'd want to run everything in conduit 
- it ain't necessary. 

Cheers,    Steve   K7LXC
Champion Radio Products

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