I'm already plotting improvements to my rover rig for June. After the January
contest, I learned a lot of lessons. I need better antennas. That means I
also need better masts. I've been looking at what a lot of other people are
doing and have come up with a solution that meets my goals of simplicity and
ruggedness. Its also quick to deploy and should be fairly effective. Keep in
mind, this is for the "limited rover" class which means 4 bands and low power.
First, I need two telescoping masts. After a lot of searching, I can't find
any commercially made masts that do what I need. After looking at Home Depot,
I settled on building my own out of EMT conduit pipe. The inner section will
be 10' long and 1" in diameter. The middle section will be 5.5' and 1.25" in
diameter and the base will be 5' long and 1.5" in diameter. There will be two
pins to lock the pieces in place in both the lowered and extended points. The
upper section has 4.5' of mast space for antennas.
The masts will be mounted in the bed of my truck. They will be attached to the
steel tool box and a cargo divider in the bed. That will give 4 mounting
u-bolts for each one and that should be pretty solid. I will also guy the
lower 5' section to the inside of the truck bed. In this configuration, the
lowest antenna would be 9' off the ground in the lowered position and 18' fully
extended. The highest antenna would be at 13' at the lowest and 22' fully
extended. All figures are a little conservative to account for spacing of the
overlap of the tubes.
The antennas I'm going with are the following: 6 meters is a Par Stressed
Moxon, 2 meters is the M2 2M7 (7 element, 8'8" boom), 222 would be from M2 in
the 222-7EZ (7 element 5'8" boom) and an M2 420-50-11 (11 element 5' boom).
Everything would be oriented forward and I would use the truck to rotate the
thing.
My question becomes about stacking order. I have about 4 feet of mast space to
work with on each mast. My thought was to put the 6 meter at the top of one
and the 432 on the top of the other. That would allow me to stagger them so
they didn't come too close to each other either vertically or horizontally.
I'm very open to hearing alternatives to this.
I will also have a single mast mounted to the trailer hitch with halos for 50,
144 and 432 for use while moving.
So what says the group? Obviously, everything is a compromise of performance
versus portability and ruggedness. I'm trying to walk a line that gets me as
good a signal as possible while not causing me problems from overly complex or
cumbersome systems.
Thanks for any suggestions.
Steve
K4GUN
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