Let me just add something here. What Tim says makes sense and I agree. But
don't confuse rovering with operating portable to pass out a rare grid for
instance. When operating from a rare grid, using the best antenna possible is
in order! Using a three or five element beam makes sense as a rover, though.
73, Paul K7CW.
--------------------------------------------
On Thu, 12/29/16, K7XC Tim Marek <k7xcnv1@gmail.com> wrote:
Subject: Re: [VHFcontesting] Yagis on masts
To: "Patrick Thomas" <p-thomas@mindspring.com>
Cc: "vhfcontesting@contesting.com" <vhfcontesting@contesting.com>
Date: Thursday, December 29, 2016, 4:27 PM
As one who was a rover
for over 30 years (often in the top 5 nationally)
please let me offer some common sense..
(1) I cant think of any reason
to carry a 50 ft pushup mast... A 20 footer
would make more sense, less weight, only 2
guys, and get your antennas high
enough to
work anything. A 20 footer that's 3 or 4 sections would
be a big
advantage.
(2) Learn quickly that 30 ft long yagis are a
huge liability physically
over any
additional gain they will provide.due their length. Strive
for 12
to 15 ft long antennas max... MAX!
(3) If you can, set up EVERY
antenna you plan to use on a mast(s) already
bolted to the rover vehicle and go down the
road with antennas at a max of
12 to 13 ft
high as gas stations and overpasses are not all created
equal.
Turning the vehicle to aim the
antennas make things much MUCH faster.
I have many more ROVER GUIDELINES that I have
learned over the 30 years I
was an active
Rover contester but don't have time to post them
here.
Trust me when I say a
50FT pushup is only for fixed stations use, not a
ROVER...
Visit
K7XC.TRIPOD.COM for pictures of what I am talking about.
73s de Tim -
K7XC - DM09jh... sk
On Wed, Dec 28, 2016 at 4:33 AM, Patrick Thomas
<p-thomas@mindspring.com>
wrote:
>
Hey all,
>
> I've
been considering augmenting the park-and-go rover setup with
a
> push-up mast. However, I have
noticed that the Rohn H50, etc., explicitly
> state that they are "not
recommended" for use with yagis. And sure,
> physics would suggest that if you have a
15' antenna boom, you are likely
> to
have more off-axis "arm" acting on the top of the
mast, versus a
> vertical or even a
dish. On the other hand, I don't know if they only
say
> that to protect themselves against
people who use H50s as semi-permanent
>
rooftop installations in 80MPH wind zones with heavy ice.
>
> So what's the
verdict? I'm sure it's "possible" but is
it safe to use a
> large 2m yagi on an
H50 when properly guyed, on a day with gentle breezes?
> Or is it indeed "not
recommended" under any conditions due to
instability,
> etc? For that matter,
what about the weight of a rotor that high up?
>
> (And yes, I'm
still working on the halo stack, so worst case I could
> always hike that up the line... but would
love to have the extra gain and
>
directionality from the yagi.)
>
> Thanks,
>
> Patrick
> KB8DGC
>
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