[TowerTalk] Fwd: Mobile Tri-ex 70 tower

Fri Jul 13 18:30:16 EDT 2018

 Unless it is a really huge tower you are, temporary, setting up, I believe a 5000 pound weight is a "little" overdone. We used the rebar type during the WRTC to hold up 40 foot Rohn 25 towers. No, they never got "tested" during high wind but I believe they could work for some good wind though.

I strongly suggest the screw anchor, with minimum 4 inch diameter auger screws, for a field-day. I don't remember for sure but believe the anchor holding my 85 foot tower are 6 inch and are rated (by the manufacturer) to hold 14000 pound screwed in to undisturbed sand. If you have something more dense they will probably hold more. 4 inch should probably be easier to screw in and screw out, you don't want to leave them after you are finished.

Regarding how many guy point you should have, yes, three are the minimum but I recommend four. The position of the guy point get a lot less critical. You can easy be of by 10 degr without compromise the integrity of your set-up and an extra guy wire with anchor is not that much more, especially if the structure collapse with major damages to the antennas etc.

Just my penny dropped down,

73 de Hans - N2JFS

-----Original Message-----
From: jimlux <jimlux at earthlink.net>
To: towertalk <towertalk at contesting.com>
Sent: Fri, Jul 13, 2018 10:14 am
Subject: Re: [TowerTalk] Mobile Tri-ex 70 tower

On 7/13/18 6:11 AM, W0MU Mike Fatchett wrote:> The problem with the trailer is that it should be "guyed" in three > directions 50 ft from the front and the outriggers.  I have not found > the original owners manual so I am not completely sure how effective the > guys really are.  I found a great manual online that a club put together > for their Field Day ops.  They drive rebar in the ground with a washer > welded at the end for the tie offs.> Speaking cynically, I think those "stakes in the ground" are more to provide a secure anchor point for the guyline so that it holds up when someone trips over it in the dark. And to mark the approximate "fall radius" for the tower, so you can make sure you don't set up an operating tent within that radius.I doubt they have any signifcant pull-out strength, so if the wind comes up, the stake will bend, pull out, and over the tower goes.*real* temporary installations designed to withstand significant wind (or seismic) loads will use auger screw anchors, or these days, I've seen a lot of use of "big blocks of concrete" or K-rail/jersey barrier. The truck drives up with the rented weights, a crane or forklift puts them in position, and you're done.  The purpose designed weights are about 5000 pounds, with a big steel loop on the top to attach a guy to. They're roughly a cubic yard in size.You could probably also use FIBC (Flexible Intermediate Bulk Carrier) bags full of gravel as weights.  They are also in the 5000 pound range.They're surprisingly inexpensive to rent - $5/day kind of numbers.  It's the delivery cost that might be pricey.> W0MU> > > On 7/12/2018 8:15 PM, john at kk9a.com wrote:>> With all of the HOAs, I'm guessing that this would be more valuable on >> the>> trailer.>>>>>> John KK9A>>>> To:    towertalk at contesting.com>> Subject:    [TowerTalk] Mobile Tri-ex 70 tower>> From:    W0MU Mike Fatchett <w0mu at w0mu.com>>> Date:    Thu, 12 Jul 2018 18:08:20 -0600>>>> Can you remove the tower from the trailer and mount these on a concrete>> base?>>>> W0MU>>>> _______________________________________________>>>>>>>> _______________________________________________>> TowerTalk mailing list>> TowerTalk at contesting.com>> http://lists.contesting.com/mailman/listinfo/towertalk> > _______________________________________________> > > > _______________________________________________> TowerTalk mailing list> TowerTalk at contesting.com> http://lists.contesting.com/mailman/listinfo/towertalk______________________________________________________________________________________________TowerTalk mailing listTowerTalk at contesting.comhttp://lists.contesting.com/mailman/listinfo/towertalk