[TowerTalk] Rotator clamp help

[kq2m at kq2m.com]

Hi Tony,

I have not used a K7NV mast clamp so I can't speak to it's performance.  
But I have been using an Orion 2800 on my top 20 - 5L LJ105CA on a 35' 
boom at 130' for the past 15 years.  In all that time with two 
hurricanes, 1 tornado, and dozens of 80+ mph wind gusts, ice storms, 
Nor'easters, etc. the mast has loosened up only twice.

My antenna is clamped against both the mast as well as the boom and 
balanced for weight at the point at which it is mounted on the boom. I 
believe that the special truss and torque clamp apparatus that I made 
and currently use may have something to do with the clamps longevity as 
it has significantly reduced the rocking of the antenna during periods 
of extremely high winds.

I have not found it necessary to purchase a K7NV clamp but those who 
have used one speak very highly of it.  The main issue is that the mast 
is circular and the stock Orion clamp is more in the shape of a "V" 
which ensures that there is far less than the maximum possible surface 
area of the clamp coming into contact with and gripping the mast.  
Weather, topography, wind and other factors come into play so that no 
two qth's will experience the same set of challenging conditions on the 
clamp.  My qth is particularly windy and turbulent and prone to 
exceptionally violent storms at times so it takes a toll sooner rather 
than later on anything up on my towers.  I'm happy with the performance 
of the stock Orion clamp but all you need is one incident of 
catastrophic clamp failure to ruin your day.   ;-)

73 and GL!

Bob, KQ2M


On 2024-09-23 14:44, Anthony DeBiasi wrote:
> I am presently using an older M2 Orion rotator.  After 22+ years it has 
> failed and needs replacing.  When I moved to Florida 3 years ago, 
> instead of using the supplied stock mast clamps I purchased a K7NV mast 
> clamp which some of you may be using.  The K7NV mast clamp definitely 
> prevents slippage although in 18 years at my last QTH which was fairly 
> windy the stock mast clamps only slipped once during a hurricane which 
> was easy to correct with the Green Heron RT-21 controller and snugging 
> up the clamp bolts. I should mention the rotator is on a 86’ Tashjian 
> tower that nests to 23’ and is fairly easy to access.
> 
> I am trying to decide if it would be better to replace the K7NV mast 
> clamp with the stock M2 mast clamps that are more likely to slip.  Why 
> would I considering the change, to possibly put less stress on the M2 
> rotator.  On the tower from the bottom up there is a JK-Mid Tri/40, a 
> 5el M2 6m yagi and on top is a WARC JK1217.  Although I live in 
> Florida, I am located about 15 miles inland and 35 miles north of 
> Tampa. We do get a lot of Thunderstorms in the summer but the wind has 
> been far less than I experienced in Northern NJ and Southern NJ.
> 
> Would appreciate the advice of anyone who has experience with either 
> the stock M2 clamps or the N7NV clamp. I know you can put a pin through 
> the clamps and mast but I wouldn’t suggest that.
> 
> 73, Tony K2SG
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