Also remember that Tashjian LM-470 specification is for 17.5 sq ft at 1 foot
above the tower, not 17.5 sq ft at the end of a 20 foot mast.
Mike, K6BR
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of K7LXC@aol.com
Sent: Friday, August 03, 2012 10:03 AM
To: towertalk@contesting.com; w1srd@yahoo.com
Subject: Re: [TowerTalk] Wind Load Spec Differences Between Tower and
Antenna
> Would like to be confident my LM-470 can handle a DB36 (17.5 sq ft
using
100 MPH EIA-222-C) .
I believe the 4 El SteppIR (9.7 sq ft) is fine on the WT51
> Usual caveats about crank it down in the wind already noted. Also,
> the
Tashjian specs are for a *new* tower. I don't know the vintage or history
of the LM-470 I have. It came with the property.
What do the current specs say? In the old days - pre-EIA-222 -
crank-ups were rated @ 50MPH. Your tower might be that vintage.
You didn't include enough specifics. What is your local windspeed
rating? You can find an older EIA-222 windspeed rating for all US counties
at _http://www.championradio.com/county.windspeed.data.html_
(http://www.championradio.com/county.windspeed.data.html) . San Mateo
County, CA, is a 70 MPH windspeed zone. Not a high wind area (70 MPH is the
minimum windspeed
rating) but crank-ups have to be treated with much care wind-wise.
You could probably get away with it but if you need to get a building
permit, forget it.
Cheers,
Steve K7LXC
TOWER TECH -
Professional tower services for hams
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