Thanks for responding. Actually, I have read and re-read "Up The Tower"
several times. It actually doesn't give specifics about where on the mast to
go. I don't understand why they sell 15' reinforced masts if they want you
to put the beam right on top of the mast. Only a collection of very light
weight 2 meter and above antennas would qualify. Also not sure why they pick
a tower height of 55' which is an odd height if comparing wavelengths of
amateur bands, being more than a half wavelength at 20 and less than a half
wavelength at 40.
So I, too, am reading all I can and asking all I can. On this issue,
actually, the ARRL Antenna Handbook makes the most sense going through the
"moment" calculations. But they come to the conclusion that there is little
difference between the top of the tower and 5' above.
Fred
-----Original Message-----
From: Tommy Alderman [mailto:aldermant@windstream.net]
Sent: Wednesday, May 12, 2010 5:17 PM
To: fserota@msn.com
Subject: FW: [TowerTalk] Best mast location?
Sorry Fred. This got sent to Gene by mistake!
73,
Tom - W4BQF
-----Original Message-----
From: Tommy Alderman [mailto:aldermant@windstream.net]
Sent: Wednesday, May 12, 2010 4:04 PM
To: 'Gene Smar'
Subject: RE: [TowerTalk] Best mast location?
Fred,
I am just in the process of putting up my first tower/yagi after 59 years in
the hobby. I seriously urge you to at least get the book 'Up The Tower' by
K7LXC because it sounds, by your posting, that you really need to learn more
about this process. I knew absolutely nothing about the process, but I have
been reading most everything I could get my hands on to learn. And for sure,
even after a year, I don't know enough yet. Because a tower says it will
support 18 sq ft, really tells you nothing. You have to do what Gene has
suggested and find out about the wind load. Because it says 18 sq ft, that
does not mean it will support a 17 sq ft yagi. You have to consider wind
loads, the mast & rotor wind load, etc. It is a rather involved process,
although not complicated when you learn the subject. 'Up The Tower' provides
you with an awful lot of the basic need-to-know information for us novice
tower builders!
73 and good luck with your project.
Tom - W4BQF
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Gene Smar
Sent: Wednesday, May 12, 2010 3:12 PM
To: Fredric T. Serota; towertalk@contesting.com
Subject: Re: [TowerTalk] Best mast location?
Fred:
The 18 sqft rating of the tower is probably based on having the antenna
load no more than 2 feet above the top of the tower. Check the tower
manufacturer's specs for the derivation of this figure. Assuming that is
the case, you would be overloading your TX455 by mounting the Yagi at seven
feet up the mast.
You also ought to be aware of the wind speed for which the tower is
rated at 18 sqft. It might be only at 50 mph winds.
Caveat Amateur!
73 de
Gene Smar AD3F
----- Original Message -----
From: "Fredric T. Serota" <fserota@msn.com>
To: <towertalk@contesting.com>
Sent: Wednesday, May 12, 2010 1:53 PM
Subject: [TowerTalk] Best mast location?
> Have a 55 ft tower rated at 18 sq ft (TX 455) a 15 ft mast and a 150 LB -
> 17 sqft multiband beam (SteppIR DB36). Question is how far up the mast
> should I mount the antenna? Would like to get to at least a half wave over
> ground for 40 meters (60-62 ft) or 7 foot of mast.
>
>
>
> Fred K3BHX
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
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