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Author Topic: Did wind do this?  (Read 2386 times)
NI0Z
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« on: June 24, 2012, 02:48:04 PM »

Much to my suprise when I walked outside yesterday and looked at my HexBeam on the roof on a GME 8 floor roof tower I saw it dangling.  The bolts from both the rotator and the thrust bearing were all gone.  You can see a picture here.

http://roaringstar.com/index.php/articles/52-birtham-mayhem

Anyone else ever experience this?  I only found two the bolts after a fairly extensive search.

Vibrations?
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K3VAT
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« Reply #1 on: June 24, 2012, 03:10:57 PM »

Much to my suprise when I walked outside yesterday and looked at my HexBeam on the roof on a GME 8 floor roof tower I saw it dangling.  The bolts from both the rotator and the thrust bearing were all gone.
... Anyone else ever experience this?  I only found two the bolts after a fairly extensive search.
Vibrations?

Mark,
Yes, I had a very similar catastrophe with a long boom yagi at 90'.  I traced the problem to improper torque on the TX2 rotator bolts and that I did not use any type of locktight.  Over the course of only several months steady variable winds vibrated all bolts complete free! 
Rich, K3VAT
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AA4PB
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« Reply #2 on: June 24, 2012, 03:33:18 PM »

Be careful with Locktight. Blue is intended for bolts that must be removed for maintenance. Red requires heat for removal.
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KC4MOP
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« Reply #3 on: June 24, 2012, 05:29:47 PM »

I did not have a catastrophic event like you, but a Yagi that was twisted in a different direction after a violent storm passed.
You may have had a microburst near your house or the wind was in a spinning motion, that caught your antenna. Check the braking action of your rotator to make sure it wasn't damaged. It looks like it should handle the HEX antenna

Fred
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W8JX
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« Reply #4 on: June 24, 2012, 06:09:01 PM »

Be careful with Locktight. Blue is intended for bolts that must be removed for maintenance. Red requires heat for removal.


Red does not lock it that tight that it will not come apart without heat. It does hold a bit more securely than blue though. Only time it is really a concern is with small screws that make snap off or strip head removing them. With bigger clamps and bolts it will come apart.
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W5DQ
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« Reply #5 on: June 24, 2012, 07:26:28 PM »

Much to my suprise when I walked outside yesterday and looked at my HexBeam on the roof on a GME 8 floor roof tower I saw it dangling.  The bolts from both the rotator and the thrust bearing were all gone.  You can see a picture here.

http://roaringstar.com/index.php/articles/52-birtham-mayhem

Anyone else ever experience this?  I only found two the bolts after a fairly extensive search.

Vibrations?


We see this sort of thing all the time out here in the Mojave desert. The heavy blowing winds cause vibrations to antenna installs and cause bolts to 'walk' out of tightness. Usually it is due to either not tightened to spec or forgetting to put in lockwashers. Luckily I haven't had any of these happen to my antennas.

Blue Loctite definitely will be a plus in preventing this happening again. Your install looks like it would be easy to check the bolts periodically to ensure they're not walking out on you.

Gene W5DQ
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
NI0Z
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« Reply #6 on: June 24, 2012, 08:59:09 PM »

Thanks everyone!  Really felt like gremlins! Grin Grin

I think the lock washers provided were my issue, I will be keeping a close eye on it this time.  I can't do the roof myself that easily, bad since balance due to a broken ear drum as a child.  I have learned a few times from a few nasty falls to just let someone else do roofs and things requiring balance. 

Can't believe I made a Japan QSO with it like that.

I used lock tight extreme this time so I hope the rotator lasts me a good while!  That is the one thing I cheaped out on a bit!
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KC4MOP
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« Reply #7 on: June 25, 2012, 03:37:10 AM »

Thanks everyone!  Really felt like gremlins! Grin Grin

I think the lock washers provided were my issue, I will be keeping a close eye on it this time.  I can't do the roof myself that easily, bad since balance due to a broken ear drum as a child.  I have learned a few times from a few nasty falls to just let someone else do roofs and things requiring balance. 

Can't believe I made a Japan QSO with it like that.

I used lock tight extreme this time so I hope the rotator lasts me a good while!  That is the one thing I cheaped out on a bit!

"LOCK NUTS"  are much better than painting Locktite all over things.
And better to be safe and stay on the ground....that is a very steep roof you have there.

Fred
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K2MK
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« Reply #8 on: June 25, 2012, 06:00:15 AM »

Quote
"LOCK NUTS"  are much better than painting Locktite all over things.
Fred

Agreed but it looks like a Yeasu rotator and thrust bearing. No nuts are used. The rotator and thrust bearing each have four threaded M8 holes.

An alternative (unusual to ham radio) would be to use bolts with small holes drilled through the heads. (Yes there are such things). You then pass a lockwire through each of the four bolt heads. There's a cool tool available for twisting the wire. The technique is used in industries where the loss of hardware is dangerous. If done properly the hardware might loosen a small amount but will never escape.
http://en.wikipedia.org/wiki/Safety_wire

73,
Mike K2MK
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KG4LMZ
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« Reply #9 on: June 25, 2012, 06:09:58 AM »

You can also get a small jig with drill bits for drilling out your own bolt heads, too.
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NJ3U
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« Reply #10 on: June 25, 2012, 06:13:21 AM »

As you find the other bolts check for signs of wear on the threads or twisting of the bolts.  I suspect that it was just a case of things loosening up over time, still if that was happening you should see signs of wear on the bolt holes in the thrust bearing plate and possibly on the rotator support brackets.

I would doubt that any weather mini twister did this since you would see broken hardware or pulled through bolts still attached.

Chances are this was going on for some time and the last one went on your BDay !  BTW did you look in the gutters ?  I would think some may have come to rest there on the way down the roof.  73 - NJ3U Rory
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AA4PB
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« Reply #11 on: June 25, 2012, 06:54:19 AM »

I would also suspect that the bolts came loose over time rather than a sudden event.

As to the red locktight, I am just quoting the mfgs specs that "blue" should be used if the bolts need to be removed and that "red" requires heat application to remove them. I guess the mfg could always be wrong. Also, locktight is not supposed to be "painted all over everything", a small amount is applied to the threads before inserting and tightening the bolts.

At any rate, the lock washers will likely take care of the problem.
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N3OX
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« Reply #12 on: June 25, 2012, 07:00:35 AM »

As to the red locktight, I am just quoting the mfgs specs that "blue" should be used if the bolts need to be removed and that "red" requires heat application to remove them. I guess the mfg could always be wrong.

I would definitely follow the manufacturer's removal instructions for bolts that are installed in tapped holes in the bottom of the rotor.  I cringe at the thought of a bolt twisting off  leaving behind a stub that's flush with the housing and still nice and solidly held in place with loctite Wink

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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
W5DQ
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« Reply #13 on: June 25, 2012, 07:58:59 AM »

Thanks everyone!  Really felt like gremlins! Grin Grin

I think the lock washers provided were my issue, I will be keeping a close eye on it this time.  I can't do the roof myself that easily, bad since balance due to a broken ear drum as a child.  I have learned a few times from a few nasty falls to just let someone else do roofs and things requiring balance. 

Can't believe I made a Japan QSO with it like that.

I used lock tight extreme this time so I hope the rotator lasts me a good while!  That is the one thing I cheaped out on a bit!


Once made a QSO with Hawaii with the tower tilted over, quad almost on the ground and facing the wrong direction. Isn't propagation a great 'weird' thing Smiley
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
KB2WIG
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« Reply #14 on: June 25, 2012, 11:18:23 AM »

This may be of interest.


http://en.wikipedia.org/wiki/Castellated_nut

klc
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