When North is not North – Deferred Maintenance has a Price

Spring at my home QTH brought some real weather extremes, including a few very high wind events.  If I know about forecasts for mega-winds in advance I will retract my tower and point the pair of Log Periodic (LPDA) Antennas into the expected direction the wind is forecast to arrive from.

But a couple times I wasn’t around or arrival of major winds wasn’t forecast, and things had to take the brunt as they are.

LPDA antennas typically have two square booms spaced apart electrically, each with half of the elements on them.  This is a fair bit of a wind-catcher compared to a typical beam where one round boom does duty.

On my heady-duty version of the Tri-Ex LM-354 tower are a Tennadyne T-8 10-20m LPDA and a T-28 6m-1.3gHz LPDA.  Book Wind Areas are 8 sqft and 3sqft, for a total if some off-center allowance is given for the chokes of approximately 12 square foot of Wind Area.   The tower in standard form is rated for 26 square feet of Wind Area using the standard design and the current heavy-duty is rated for 52 sqft, so nothing about the antenna loadings themselves being pushed hard there.

Tri-Ex/Tashjian: http://www.tashtowers.com/crank-up-towers.php

Tennadyne:  http://www.tennadyne.com/specs&prices.htm

I’d retrofitted the T-8 with SlippNott high strength attachments back in 2013 – https://k9zw.wordpress.com/2013/06/09/installing-slippnott-upgrades-at-k9zw/  which included an added fitment at the rotor to secure the mast.

The winds had slightly pushed the T-28 from its alignment with the T-8 and rotation is now indicating about 95 degrees further clockwise than actual.

There is a chance something electrical is messed up, as the same high winds did pull all feed lines and rotor cable from the standoffs.  Apparently the breakable restraints either died with UV, Cold and Age, or the winds were strong enough to peel the lines free.

Otherwise either the rotor has broken free or something has slipped.

Of course it is raining, the ground soggy, cold and the scaffold I usually use for service one the tower is down and tipped over just happens to be 130 miles (including six important water miles) away ay the Island QTH.

I have a freshly rebuilt Ham-IV rotor which would be an easy swap if it is a rotor issue, or this might be the time to put in the AlfaSpid RAK Rotor I’d bought at Dayton-2014 but hadn’t yet installed.  Being a bit lazy about replacing things that are working okay, I’d changed my mind and I’d intended the AlfaSpid to go to the Island QTH.  So if I use it I will need to buy another.

Usually every Autumn the Tower gets lowered and tipped over, and a full PM (Preventive Maintenance) completed.  Because of the acquisition of the Island QTH and a heavy work load this PM got skipped in 2014 and 2015.  My bad, to say the least.

So now I get to pull the PM with an extra Troubleshooting Task.  Want to bet I made something worse by skipping the PM?

73

Steve
K9ZW

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