Beginner rover, participated in the July CQ contest from 8 grids. My setup
takes a long time (30-40 minutes) to construct and break down, so travel and
setup/breakdown leaves little time for making contacts. [I have a ~30 ft
walk-up mast on trailer hitch (a Penninger Radio system) and keep the antennas
inside the minivan, so I have to assemble the mast and assemble all 3 antennas
on the mast and connect coax each time.] For Sept., I'll have a short boom 6m
3el, a 2m 7el, and a 432 15el.
I've been trying to mount loop antennas (M2 "HO" series) on the roof rack rails
so I have some limited capabilities on the road and quick grid stops (in
addition to the walk-up mast for longer stops). However, I'm getting frustrated
trying to mount them (especially the 6m) because they use skinny half-inch
masts with standard 3/8 threads. Way too whippy IMHO for highway speeds and
there would be tremendous stress on the bolt or nut holding the mast on the
mounting plate. Tried using a very stiff antenna spring, but the 6m just
flopped over from it's (non-symmetrical) weight. I could get some strain relief
with a couple of guy ropes, but I can't get guys in 3 directions, just 2 at a
right angle. I'm thinking of using PVC to get both pull and push forces on the
masts, but the arrangement I'm starting to try is a horrible hack of cut up PVC
connectors and hose clamps.
Since the loop antennas are turning into a big project anyway, I was
considering mounting my yagis for use on the road. I'm pretty nervous about it,
but I think mechanically I could do it from the trailer hitch with my existing
system. Here's some concerns (besides the concern that the antennas will come
flying off on the highway and cause a horrific accident):
1. I'll only have 5ft of mast or less above the roof. Having the 432
lowest at 1 foot above the roof, that only leaves 2ft max spacing between the
antennas. Is it even worth doing with the antennas squeezed so close together?
2. I don't have a Moxon for 6m, just the short 3el. Having the 6m point
down the major axis of the van would be too wide for travel, so I'll have to
have it at a right angle to the other two antennas pointing down the major
axis. I understand that will be a PITA to have to turn 90 degrees when changing
bands with a contact, but my bigger concern is how much performance will be
hurt.
3. I've seen plenty of pictures of rovers with antennas overhanging the
back of the vehicle, but I've always wondered about the legality and safety of
that arrangement. What if any flags and lights do you put on the overhanging
antennas? My antennas will extend 42-56 inches back from the trailer hitch,
which is right against the bumper.
4. OTOH, I'm hoping when I stop to do a full setup, I'll save some time
by having fully-assembled antennas and coax on the top mast segment already ...
though taking off the populated segment and moving it to the end of the
assembled long mast will be a challenge.
Thanks for reading through this long post. Is there a better way to do the HO
loops, or should I just use two guy ropes and stop worrying? Or, is the
compromise mounting of the yagis a better way to go? I appreciate your thoughts.
-- Pete K0BAK
_______________________________________________
VHFcontesting mailing list
VHFcontesting@contesting.com
http://lists.contesting.com/mailman/listinfo/vhfcontesting
|