On May 27, 2009, at 11:58 PM, n3_kkm wrote:
> For those of you who rove with beam antennas I'm interested to know if
> you use the standard antenna mounting hardware (U bolts, Nuts,
> Wrenches,
> etc.) or is there another technique that's quicker/easier?
Yup. Lots of dead bugs on the antennas after a weekend of driving
back-roads in farm country, but no damage to the antennas. Tighten
them up good, and prep for the worst... have the wrenches necessary
handy in a baggie or toolbox in the vehicle, and don't build your
stack in such a way that you can't LAY IT DOWN to tighten something...
if something comes loose. Never had it happen, but I thought about
what I would do by myself without a 10' ladder to get up there in the
back-country on the fixed mast... so the design was done with an old
hitch-mounted bike rack that could have a pin removed to lay it down
and repair an antenna if necessary.
On 6m -- I use loops... a beam would be nice, but isn't in the budget,
nor would it survive @ 75 MPH, I don't think. Most rover photos I've
seen either have loops for 6m, or have masts that fold over for
"motion" and then have to be put back up at each stop. The fixed
mast, as long as you know you have the overhead clearance and are
smart enough not to drive under an overhang at a truck stop in the
middle of the night when you're tired... is simpler and more in the
KISS principal. Plus, if you're pointed the right way while in
motion, you still have your gain antennas, and can work folks.
(I-76 from Sterling to Denver is *generally* pointed at the Denver
Metro area, and you can work a bunch of folks while you're driving
"back in" to Denver that way.)
One year I used a log periodic for everything except 6m & 10 GHz, and
wasn't super-impressed with the performance, but it worked. Had 2m,
222, 432, 902, and 1.2 on that antenna via switches.
Everything was the "expected" 3dB weaker or more... and dealing with
all the switches to hook multiple rigs to the single antenna was a
pain in the butt. I decided the complexity and "mess" of individual
band antennas performed a lot better the prior year, and I'd go back
to that.
Plus most antenna switches are lossy at those frequencies also...
nothing out there today is rated for use above 432. I had decided
that I would disconnect 902 and/or 1.2 from the antenna switch and
compare if I was having any problems making contacts with them, but
the contacts were made without drama, and I never bothered to measure
or check the difference. The LPDA was quite unhappy on 432, and on
Day 2, I quickly slapped a 432 antenna on the mast and moved it off of
the LPDA because it was driving me nuts.
But, if someone were trying to get started relatively inexpensively on
a whole bunch of bands, since bands are multipliers, and gain toward
the horizon is better than none... one of the broadbanded LPDA's by
itself on a mast, isn't a bad way to start, compared to verticals on a
beginning rover outing.
--
Nate Duehr, WY0X
nate@natetech.com
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