In a message dated 9/30/02 1:19:41 PM Pacific Daylight Time, W4EF@dellroy.com
writes:
> Aren't those Rohn
> specs for 45G super conservative (8sq ft at 90 MPH) because they
> place the top set of guys so far below the top of the tower?
Rohn specs aren't "super conservative" - they merely conform to standards
such as the TIA-222.
The published Rohn tower specs and configurations are for commercial
applications where you may have antennas and microwave dishes that need more
headroom clearance. If you read the General Notes under the tower heighth
charts, you'll see that Rohn has already subtracted 8 sq.ft. for a
'symmetrical' mount. You can add the 8 sq.ft. back into the capacity figure
for ham purposes.
Yes, the guys should be placed as close to the top of the tower as
practical.
> I would expect
> that a properly guyed 70' x 45G tower would be capable of holding up
> 20 sqft+ in a 90 MPH wind if the top set of guys were placed reasonably
> close to the top of the tower.
I don't have my Rohn catalog in front of me but if you consider the above
statement, you may be right if perhaps a little overstated.
> For that reason alone I would go with the
> 45G tower. On the other hand, getting antennas on and off the guyed tower
> is a little more work (tram line) versus straight up and down.
The same problem with a self-supporting tower since the bottom sections
can be reasonably large - 4-6 feet.
BTW Rohn catalogs are available from <A
HREF="http://www.championradio.com";>www.championradio.com</A>.
Cheers,
Steve K7LXC
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