[ADXA] rotator mast pinning

[k5cs]

Today at the Mena Hamfest there was a guy selling out a silent key 
estate.  On the table was a Yaesu G-2800 rotor - new in the box.  He 
told me he was trying to get $1150 for it.  While I didn't need anything 
that heavy duty I told him I would think about it.  Well, I went back by 
later and it was gone.  He said he sold it for $850 cash!  You win 
some...and then...you lose some. No great loss for me, I didn't need it 
anyway.

-Charles, K5CS


On 9/7/2024 6:55 PM, Dennis Schaefer wrote:
> After my comment about pinning the mast, I thought I should research 
> the issue again since I’m getting ready to swap out a rotator.   I 
> have to say right up front that in the last 35 years or so, I have 
> never gone up the tower to correct an aiming error.   With rotator 
> repairs and several antenna change-outs during that time, making  sure 
> the mast clamps were properly tightened every few years did the job.
>
> I read lots of comments, many in the old tower talk forum, where the 
> big dogs hung out.  The word most often associated with NOT pinning 
> the mast was “nuisance” or “inconvenience”.  The words most often 
> associated with pinning the mast was “catastrophic failure”.    A 
> reason often given for pinning the mast was “Yaesu said to do it”.
>
> I understand that catastrophic failure caused by pinning  is rare and 
> unlikely, but brake wedge failure and bell housing damage were often 
> mentioned.  This would probably only occur with a very large and/or 
> unbalanced antenna.   The problem is that big antennas  exert more 
> torque and are more likely to cause slippage.  Pinning the mast might 
> be  necessary for those really big antennas.  You’re going to spend 
> time and money maintaining a large antenna system anyway.
>
> My antennas have usually been relatively small tribanders, except for 
> the Mosley PRO-57, which was a little larger.  My C-3 has been trouble 
> free and slippage free for over 20 years and I don’t expect any 
> problems.  If I had a 30 foot boom, I would anticipate problems, such 
> as more rotator failure, weather damage, sheared mast pin bolts, etc.  
> That’s one reason I stick with smaller antennas.
>
> This article seems sensible:
> https://ve3vn.blogspot.com/2022/02/hy-gain-rotator-mast-slippage.html
>
> I just remembered something - At our club station, we had a KLM 
> KT-34XA, which was a pretty big tribander.  (about a 36 foot boom and 
> very unbalanced).  We found a bunch of ball bearings on the ground 
> from its Ham-4 after some wind.  I don’t remember if the mast was 
> pinned, or just good and tight, but it did not slip, and there was 
> catastrophic damage to the rotator.  Would it have helped if the mast 
> had slipped?  Maybe, maybe not.
>
> I’m not trying to change anyone’s mind, or soliciting comments or 
> arguments - it’s like politics, everyone has their minds made up.  By 
> all means, do what you are comfortable with.   I just did this 
> research to refresh my knowledge and wanted to share my thoughts.   I 
> learn a lot from ADXA members and seldom have anything technical to 
> contribute.
>
> 73,
> Dennis/RZ
>
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