[VHFcontesting] Yagis on masts

[Paul Kiesel]

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 at gmail.com> wrote:

 Subject: Re: [VHFcontesting] Yagis on masts
 To: "Patrick Thomas" <p-thomas at mindspring.com>
 Cc: "vhfcontesting at contesting.com" <vhfcontesting at 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 at 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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