[TowerTalk] Weight of mast material

[Mahlon Haunschild]

I don't know about the mast per se, but your overall plan concerns me.

Assuming that the 40m antenna you are talking about is the Cushcraft 
XM240, a little math shows:

            Weight      Wind area (sq ft)
mast         90                2 (est.)
C31XR        82               10.7
XM240        55                5.5

totals       227              18.2

Rohn 25G is only rated for 8 sq ft at 70 ft. & 110 mph per their 
drawings (you are in 105 mph land, per EIA/TIA 222, so you need to 
design for that).  Also, 227 lbs rotating weight is a LOT for the 25G 
structure to withstand.  How will you control the torque caused by the 
antenna stopping & windmilling?

If you're married to the idea of a 70 ft 25G tower, one thing you should 
do is get an aluminum alloy mast.  Cuts down the weight dramatically. 
Another thing to do would be to not use a 40m beam.

regards,

Mahlon - K4OQ


Julio Peralta wrote:

> Thanks to all who replied RE: the weight of Chromolly. I think it would be safe to figure it a about 90#.
> 
> Our radio club here in Tampa is considering using this mast to support a Force 12 C-31XR and a shorty 40, maybe the Cushcraft, on a Rohn 25 tower.
> 
> Does anyone see a problem with the weight of the mast material in this application? 
> 
> The tower is planed for 70' and guyed at 3 points.
> 
> Julio, W4HY