[TowerTalk] Rotor choices today?

[K7LXC@aol.com]

In a message dated 12/26/00 7:53:08 PM Pacific Standard Time, 
kf9yh@netnitco.net writes:

> I have moved to a new location and finally got a few acres. I am
>  able to put up a decent tower now (Going to be a Trylon Titan
>  72 or 80 footer). I have 16' of .25 wall T-6061 tubing I'd like to
>  use for the mast along with 2 thrust bearings.
>  
>  I currently have a Ham IV rotor that I used at the old QTH. It
>  isn't up to the loads of the new system.
>  
>  I am putting up an F12 C-31XR at the top and an EF240 above it.
>  A couple of VHF antennas will be above that. I am side mounting 
>  my old C-3 at about 55'. Along with the mast and a vertical at the
>  top, the wind load will be approx. 20 sq. ft. I want a little cushion in
>  there, too. 

    First of all, Lake County is a 75 MPH windspeed zone so it's not much of 
a big deal wind-wise.

    With the factory recommended spacing of 12 feet, according to my MARC 
Program (Mast, Antenna and Rotator Calculator) you need a mast with 40,000 
psi yield strength. Your 6061 is about 35,000 psi so you're pushing things a 
bit on the mast.

    Also the rotator calc gives 2768 ft/lbs of Effective Moment or Yaesu K 
Factor for your array. Since the Ham IV is rated at 2800, it's right at it's 
limit (or over it according to your experience). A TailTwister is rated at 
3400 so that would work FB.

    A Yaesu G-2800 is rated at 6870 ft/lbs so that would be plenty. Also the 
M2 Orion 2800 is an excellent rotator second only to a prop pitch so that 
would be another option. These are both significantly more expensive than a 
T2X.

    The jury is still out on the Big Boys. Parts availability, repairs and 
reliability have not been proven at this point. And, like some Japanese 
rotators imported over the years, they could become orphans if the current 
distributor stops handling them. 
>  
>  Without breaking the bank, what would be a good rotor choice for
>  my setup? I am in NW Indiana, and do get some pretty good ice
>  loads (Maybe 2 or 3 a winter). So far, I have looked at the Yaesu
>  G-1000SDX and the Yaesu 2800. I don't think a Tailtwister gives
>  me enough cushion to do the job (Plus, they seem to be scarce
>  nowadays). I have looked through the archives, but everyone's
>  setup is different.......

    The G-1000 is rated at 2020 ft/lbs - even less than the Ham IV. 

    If it was my installation I'd go for the T2X - good value, it'll handle 
your array and just about anyone can work on it. 

Cheers,    Steve     K7LXC
Tower Tech 

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