[VHFcontesting] Brain pickin' time

[kb7dqh at donobi.net]

Guess it depends on what kind of hills you got... Hills that slope steeply
in all directions from the operating point the antennae will work fine
with not much height, just get them high enough to turn without banging
into folks wandering around the site. HOWEVER, with "big power" one would
want to
get the aluminum high enough to keep from cooking the eyeballs of the
operators!  Then you are looking at 30 or more feet "to be sure"... This
height would also get the 6 meter antenna up where it will play well and
have good low-angle radiation if you are positioned where the ground
near-field is relatively flat.

One can dig thru the "front page gallery" of the Pacific Northwest VHF
Society website and spot my VW Bus-mounted 3 section, tilt-over crankup
structure I welded up out of 1/2" and 3/4" EMT and scrap round stock...

Surprisingly, that thing could hold up whatever you could safely mount
(without a thrust bearing:-) onto an HD 73 rotator... although in the
"front page" photo you can spot a Tailtwister...

Later I reconfigured the tower, eliminating the top section and reducing the
total height by only 8 feet but increased significantly what I could
safely stick on top...  I have since added EMT "backstays" to it so that I
can mount the base to the front bumper of "Enterprise II" (The Big White
Bus)
and the backstays to the mirror mounts, adding a third antenna support if
required.

Construction of the original tower took around 40 hours of labor and 75
cubic feet of Oxygen and Acetylene to weld together.  Including the boat
winch, wire rope, pulleys and miscellaneous hardware, I think I had less
than $300.00 invested back in 1993 when I built it.  Now I have a MIG, so
duplicating would cost much less:-)

Eric
KB7DQH




> As with real estate where there is no substitution for location,
> location & location in the V/UHF RF world their is no substitute for
> height, height & (even more) height.
>
> Now, for a rover what are your "opinions" (I know everyone has one and
> they all stink) for the minimum, and maximum height for a 4 band
> (50/144/222/432) portable tower similar to these;
>
> http://www.arrl.org/news/features/2006/07/19/1/?nc=1
> http://home.comcast.net/~k8cc/Tower_Trailer.htm
>
> And I'm not even going to ask how much this bad boy costs
> http://www.alumatower.com/new/trailertowers.html
>
>
> --
> Mike Urich, KA5CVH
> http://ka5cvh.com
> http://twitter.com/KA5CVH
>
> Life is hard, faith shouldn't be
> http://fairmontpark.org
>
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