FWIW:
I roved with Tom for years. We kept our antenna farm rather small using
pushup masts. We used 8' or less (mostly 6 foot) yagis so even if they
turned sideways, they would not hang out over the road.
Also as I get older it becomes exponentially harder work. I found for small
arrays, push up fiberglass masts worked very well. We had 3 masts: One for
the six meter beam or loop. One for 144, 222, 432 and 1296. the third one
was for the microwave dish (the bottom section for the dish was heavy wall
aluminum for stability) the upper section was an H frame for 903, 2304, and
3456. No guys except when we wanted to push 6 meters al the way up to 35
feet.
You can get a good idea of it from my web site:
http://www.wa2iid.net/
click on the pictures and they will show large views.
clicking on the picture on the home page shows the operating positions
Good luck
Jack
WA2IID
-----Original Message-----
From: Patrick Thomas [mailto:p-thomas@mindspring.com]
Sent: Tuesday, December 27, 2016 11:33 PM
To: vhfcontesting@contesting.com
Subject: [VHFcontesting] Yagis on masts
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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