[TowerTalk] Force 12: rivets, hardware

[K7LXC@aol.com]

In a message dated 97-11-15 13:52:37 EST, ldennis@mediaone.net writes:

> Rivets:  The rivet holes holding the bracket for the 20m radiator element
to 
> the boom have elongated in the vertical dimension allowing the element to 
> rotate in the vertical plane.  The elongation is small at this time, but I 
> can physically move the element perhaps + or - 10 degrees.  It is likely to

> get worse--especially through the winter season (Massachusetts).  It
appears 
> that the rivets need to be drilled out and the mounting bracket replaced.  
> One should note that this bracket came from the factory already riveted to 
> the boom.  The other major mounting bracket for the 20m parasitic element 
> seems to be fine.

Hi, Dennis --

     Of course the jury is still out on the service life of rivet element
fasteners as well as the overall performance and reliability of Force 12
antennas (the oldest ones are only 3 years old). 

     Rivets have their detractors. I think Dick Weber (a licensed
Professional Engineer), K5IU, had some reservations about their reliability.
Texas hams feel that they have challenging antenna reliability problems. It
sounds like you may be one of the detractors also. 

     I haven't seen this particular problem before and I am glad you have
posted it. 
>  
>  Hardware:  Just about all the hardware has corroded--including u-bolts, 
> bolts, washers and nuts.  Should I expect that the Force 12 hardware should

> be able to last more than one season--even in a salty environment?
>  
     The best tower hardware is hot-dipped galvanized steel. It is not very
common and is not usually included with ham tower and antenna products.
Antenna manufacturers have upgraded from plated hardware to stainless steel
but it has its limitations also. It's damn tough to get much service life
when you have a hostile enviornment like saltwater. You can use additional
coatings over the hardware to get more life out of it. Check with a local
marine supply or industrial coating supplier. 

    The world winning contest station built by Ville, OH2MM, and other
sporting Finns overlooking the Atlantic Ocean in EA8 totally deteriorated in
just a couple of years. There's an interesting story about the station, it's
successes and it's environmental problems in the premier issue (January,
1996) of CQ Contest magazine. 

      It's not an uncommon problem. Let us know what you find out.

73,  Steve  K7LXC

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