[TowerTalk] Force 12 C49XR improving boom-mast attachment?

[K7LXC@aol.com]

In a message dated 12/11/00 7:29:17 AM Pacific Standard Time, 
wb0gaz@hotmail.com writes:

> Force 12 C49XR (giant 3-band yagi) was installed on my tower (2"steel mast) 
> this fall and has been working well.  Elected at install time not to pin 
> the boom-mast clamp to the mast as I didn't want to drill through the mast (
> there are antennas above it and I didn't want to risk the integrity of the 
> mast.) Noticed last week that the C49 had rotated several degrees azimuth 
> away from the others in the stack so I presume the clamp plate has slipped 
on 
> the mast due either to wind or start-stop torque 

    I'd go ahead and pin the boom-to-mast clamp; as you mentioned a 2-inch 
mast doesn't give you much meat to hold that big of an antenna. What antennas 
do you have above the big mutha?

    I think that the U-bolts above your pinning hole will provide some 
support above your stress riser mast hole. Arapahoe County is an 85 MPH 
windspeed zone so you're right to be careful. 

    Otherwise just recalibrate the antenna; several degrees ain't much - you 
could even leave it until it gets worse. This will avoid any mast compromises 
and is pretty cheap compared to any sort of failure. 

    One thing I've noticed with late model F12 antennas is that they are 
using 5/8" (socket size) nuts instead of the 9/16" they had used previously. 
The problem is that the nuts are thinner and only have 4 threads instead of 
5, thus lowering the nut holding power by 20%. Double-nutting your U-bolts 
might fix the problem - it's worth a try before drilling anyway. 

> (I'm using a Prosistel "C" 
> box which has ramp-down control but I don't know if it does ramp-down 
> during manually controlled rotation or just during point-and-rotate.)

    Please keep us informed on your experience with the Prosistel. What are 
you using for a mast clamp? Which controller are you using? Wadda ya think so 
far? Any installation problems? Any use problems?

Cheers,    Steve    K7LXC
Tower Tech 

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