Keith,
I know this isn't a popular message; however...
The actual experience of three different PVRCers who tried to turn full size 3
element 40M Yagis and SteppIR MonstIR Yagis with Orion 2800 rotators is that
the rotator was quickly destroyed by normal heavy
winds.
You don't want your new antenna project keeping you awake at night
during heavy winds! That's no fun.
My recommendation is that you sell that 2800 and purchase a rebuilt
prop pitch from K7NV. You will sleep well and it will not de destroyed by any
wind.
I'm not down on 2800 rotators, I have four of them and they are great
for anything smaller than a full size 3 element 40M Yagi or a SteppIR
MonstIR.
73!
Frank
W3LPL
---- Original message ----
>Date: Sun, 22 Apr 2007 17:21:11 -0500
>From: "Keith Dutson" <kdutson@sbcglobal.net>
>Subject: Re: [TowerTalk] Mast slipping
>To: <K7LXC@aol.com>, <towertalk@contesting.com>, <alwilliams@olywa.net>
>
>Ya'll have me wondering about my 40M tower plan. Last fall I took delivery
>of two M2 40M4LLDD Yagis. This antenna has 4 elements on a 42 foot boom,
>but a surprisingly sparse 13 square feet windload rating. They will be
>mounted at 100 and 200 feet on a 190 foot Rohn 55G tower. The top antenna
>will be rotated by an Orion 2800 that was purchased at the same time. The
>lower will be rotated by a TIC Ring.
>
>This tower was supposed to be going up this spring but unexpected surgery
>has delayed the project for a year.
>
>After hearing about all of the mast slipping problems I decided to take the
>Orion out of its box and have a look. According to the instructions, the
>"positioner" has been recently improved and strengthened. Since I do not
>have an older unit, I have no way of knowing what is improved or how much
>stronger it is. Here are some specs:
>
>wind area 35 sq ft
>start torque 4200 in lb
>rotating torque 3200 in lb
>braking torque 17000 in lbs
>vert load cap 1800 lbs
>
>I took a photo of the mast clamp halves (see below). Interestingly, there
>is a hole in each that is sized to take a 1/4 inch bolt. This could
>certainly be used to pin the mast but leaves doubt about the strength to
>hold it.
>
>http://www.dutson.net/Transfer/HamRadio/Orion2800Clampds.JPG
>
>73, Keith NM5G
>
>-----Original Message-----
>From: towertalk-bounces@contesting.com
>[mailto:towertalk-bounces@contesting.com] On Behalf Of K7LXC@aol.com
>Sent: Sunday, April 22, 2007 12:04 PM
>To: towertalk@contesting.com; alwilliams@olywa.net
>Subject: Re: [TowerTalk] Mast slipping
>
>
>In a message dated 4/22/2007 8:43:23 A.M. Pacific Daylight Time,
>towertalk-request@contesting.com writes:
>
>> About a year ago I had a conversation with the m2 people about their
>rotator
>clamp slipping on my Monstr's mast. What follows is my memory of the
>conversation:
>
>> 1. It is better to have the clamp slip than to harm the rotator. (Note:
>
>the
>wind banging repeatedly on the gearing can weaken the gears?)
>
>> 2. The specified braking torque has not been measured (or calculated?).
>
>> 3. Pinning voids the warranty. I would assume that using a
>> different
>mfrs
>clamp would also void the warranty.
>
>> 4. They recommended a clamp bolt tightening sequence that should be
>followed. Unfortunately I wasn't able to get a firm answer on what torque
>to tighten the nuts to. The sequence to follow is:
>
>> a) bolt the rotator to the mounting plate but leave the bolt/nuts
>> not
>tightened
>b) with the bolts to holding the rotator to the mounting plate loose,
>tighten the bolt/nut pair of the clamp that is nearest the bottom.
>c) tighten the next (middle) bolt/nut pair of the clamp
>d) tighten the top bolt/nut pair of the clamp
>e) repeat steps b,c,d several times
>f) now lastly, tighten the bolt/nuts of step a
>
>> I did get an answer of 40 ft/lbs from the m2 person but I think that
>> was
>just pulled out of the air.
>
> Very interesting but not useful. It doesn't do anything about the
>significant design flaws of the Orion mast clamp that ARE the problems.
>None of the above will keep the mast from slipping.
>
>Cheers,
>Steve K7LXC
>TOWER TECH
>
>
>
>
>
>
>
>************************************** See what's free at
>http://www.aol.com.
>_______________________________________________
>
>
>
>_______________________________________________
>TowerTalk mailing list
>TowerTalk@contesting.com
>http://lists.contesting.com/mailman/listinfo/towertalk
>
>_______________________________________________
>
>
>
>_______________________________________________
>TowerTalk mailing list
>TowerTalk@contesting.com
>http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|
