[NLRS] Looking for Mounting Help

[Doug Reed]

Hi Scott.

Many NLRS ops run rover in the VHF contests. You didn't say what year
Honda Pilot, does it have a trailer hitch, does it have a roof rack?
Does the little side window near the back open?

I have never operated rover mobile, only portable, so this is mostly
from observing rigs at our annual Aurora conference in April. I do
take pictures of the ones I liked best. For portable ops, I liked
having a guyed mast outside the drivers door and I could reach out to
point the antenna by hand in seconds, Not well suited for winter
contests. :-)

Most systems are either mounted on the roof rack or mounted to the
trailer hitch. Cable entry is where ever you can bring them in with
least interference, that usually means a window. Consider some "foam
pipe insulation" over the edge of the glass as protection for the
cable and weather seal. Are you going to drive and operate while
stopped or will someone else drive while you operate? Where will the
equipment be in the car?

Roof racks are usually either wood or PVC pipe. Most of the time they
will be fixed in the forward direction and you point the car toward
the station. If you really want to turn the antennas while stopped,
you can mount a small tripod to the rack, with a rotor and short mast
for the beam. But remember to always point it forward before you move.
And you will probably need to provide AC to turn any cheap rotor. And
always remember 12ft maximum height above ground to go under bridges,
and that trees and some bridges are lower than that. Trees eat
antennas.

Many people use the trailer hitch mount. If you have one on the car,
that might be the better option if your roof rack isn't very sturdy.
I'd say that the best masts I've seen are usually square metal tubing
with holes and additional sections are nested inside so they can be
raised for extra height at each stop. I want to suggest the best
option for rotating the mast is with the rotor mounted at the bottom
on the hitch bar. You will want to have a couple sturdy braces from
the mast forward to the roof rack. And you would need some sort of
bearing to allow the mast to rotate in the bracing. The main negatives
for trailer hitch mounting is you can't open the hatch while it is in
place and the antennas are a long overhang in the rear so you need a
flag and I'm sure there is a max overhang length by law.

If you don't like the rotor at the bottom and bearing option, maybe
you can find a couple of the old Alliance U100 rotors that have a hole
all the way through the rotor for the mast. They are ancient and not
very strong, but I used a pair of them on my house with a pair of
beams through some severe storms and they held up for 10 years. The
trick is to take the motor out of one body and use just the empty
housing as a bearing and support for the mast, with the other unit a
couple feet higher on the support to turn the antennas. They spread
the weight load and the spacing helps keep the mast vertical so it
doesn't destroy a single rotor. Keep in mind that driving 70MPH would
be considered severe weather with broken branches near 3" diameter.
Add a 30MPH headwind and now it is 100MPH wind load, hurricane
strength.

I would suggest that for the beginner, the roof rack is probably
simplest. Wood is probably more sturdy than PVC, but you would
probably be OK with 2" or 1.5" PVC pipe to get as much strength as
possible. That will come down to how big is the dual band beam?

A minimum sort of structure might be a large square, the length of the
roof rack and 5ft high. Mount it vertically front and back to a pair
of 2x4 studs that go across the roof and are anchored to the roof rack
on both sides. This structure should stand on its own but will not be
sturdy enough to hold anything until you add ropes as guy wires to
form triangles in all directions. I would brace the top corner to each
end of the 2x4 bottom mount and run two more ropes from corner to
corner of the pipe frame. The simple way to mount the beam would be to
attach it to the top pipe of the frame so it always points forward.

Don't take this as a suggestion for a proven design. It is just a
guess for a minimum structure that would probably hold a small antenna
without too much difficulty. The only real strength comes from the
rope guys that stress the frame to reduce bending. You might even need
to run an extra pair of guy ropes forward to the front bumper of the
car. I'm really worried about how well the frame will handle the wind
load at highway speed. Personally, I would probably use "550 paracord"
for the rope. It needs to be strong and with minimum stretch. You may
want to add turnbuckles to allow tightening the ropes, or you could
try the cheap alternative of winding a wood dowel into the rope for
tensioning. On second thought, a $10 package of 4 cheap ratchet straps
might be better than ropes.

And plug the ends of any open pipe because they will sing when you
drive down the road. It becomes very tiring.....

Probably the best thing about this frame is that it will be pretty
light to install and remove. One person can probably handle it but a
second person would make it easy. But the first step is figure out how
to attach to the roof rack.... U-bolts would be good, or maybe you
have a spare set of cross arms for the roof rack that you can mount
to? How about a 2x2 on the bottom, U-bolted to the cross arm. Two 1x4
on either side up to another 2x2 for the top rail. Use screws & glue,
not nails, maybe add some pipe strap for extra strength? Still want
the ropes or straps to brace everything.... Can't get much cheaper
than that but it would be harder to install without a helper.....

And don't forget power requirements. You WILL want a deep-cycle
battery to run the radio when stopped. Do not rely on the car battery
for power when stopped or you might be stranded. Keeping the radio
battery charged means running the car or a portable generator. The 2KW
portable Inverter generators are very popular, expensive, and QUIET.
You can estimate how long you can operate from the radio battery
before it needs charging. The charger has to be big enough to charge
while transmitting. Charging a second battery from the car alternator
will probably require some heavier wire run from the existing battery.
I never had any luck when plugged into a cigarette lighter of similar
connection. For winter roving you either run the car heater or use the
portable generator to run a heater. And you will have fun keeping
frost off the windows....

You will want the option for digital modes too. That means a laptop or
other computer and now you need power for it without relying on the
laptop battery. That means a DC-DC laptop power supply or an AC power
source. And I'd probably say that you should consider getting one of
the DC-DC converters designed to regulate the battery voltage to 13.6V
at all times. Many radios get flakey when the DC voltage drops. The
step-up regulator will keep the radio working while the battery
voltage drops. All these DC-DC converters and AC inverters need to be
tested to prove they don't make RF noise.... Ferrite chokes are your
friend...

I don't remember if NLRS has any "Rover Row" pictures on the web site,
but I bet they exist somewhere if you search the web. That will get
you a lot more ideas.

73, Doug Reed, N0NAS.

-- 
I vote the Second Amendment FIRST!

Enjoy life, it has an expiration date!