ARC-SETs
An ARC-SET is a truly miraculous device! It will put any "Polar" mounted, parabolic Dish, precisely onto the ARC, in a matter of minutes, without reliance on a compass, and without the post having to be plumb! It is an exacting Analog Computer, using ever-present gravity and a single Satellite's signal strength, to get you home in time for dinner. It is sufficiently accurate for unforgiving Ku-Band birds! The ARC-SET is used as follows:
Place your ARC-SET on the Axis of your Mount, and adjust the
elevation setting of your Mount to center that bubble marked
AXIS. The Axis is the line between the pivot points on which
your Dish will be turning as it is actuated through the
Satellites. Where you physically put your ARC-SET depends on
the variety and design of mount mechanisms which you encounter.
The AXIS inclination is the same for all "Polar" Mounts, even
under spoon dishes. On some totally enclosed horizon-to-horizon
drives, the Axis is buried inaccessibly inside the machanism,
but you can expose the semi-circular gear and use your ARC-SET's
ends (which are exactly perpendicular to its magnetized edges) against the gear's face.
After having first set the AXIS elevation, transfer your ARC-SET to your Dish,
perpendicular to its parabolic axis (your Dish's "look direction"). If it is a parabolic
Dish, your ARC-SET will be parallel to the lip-to-lip slope of
the Dish face. If it is a Spoon Dish, its real look direction
will not be perpendicular to the lip-to-lip slope of the face.
Usually, some surface on the back of the Dish is available to provide
reference. Failing that, you can
always use the lip-to-lip slope
across the face of your Dish. Your
ARC-SET is now above the Declination adjustment, and you use
the Declination adjustment to center your ZENITH bubble. This
is done with the Dish swung (actuated) up to its highest look
angle (its Zenith) -- as if looking South. Your ARC-SET will be on the Dish, parallel to the
line of the Mount's Axis. Your Declination (aka Off-Set Angle) equals: ZENITH - AXIS.
Now comes the fun (miraculous!) part: lower the dish, by its actuator to the side with
your lowest active Satellite. The Satellite can be partially
obstructed(the picture does not have to be "watchable" for your
client -- just sufficiently detectable to tell you and your CANARY when/where you
have peaked its signal). As you actuate the Dish toward that
side, you can use the same slope reference surface as for the
ZENITH, but you must turn your ARC-SET to follow the Dish's
steepening slope. Turning (like a wind-shield wiper) to center
the little bubbles, in the end of the EXTREME & ZENITH sections,
guides you to the slope's steepest angle. Actuate the Dish down
until its steepest slope centers the EXTREME bubble. This gives
your Dish the appropriate look angle for the Satellite. Then
twist the Dish in azimuth (around its ground pipe) to peak up
that Satellite's signal. This orients the Axis to True
North/South (better than a compass) and brings your System's actuation track onto the Arc!
If the pst is not plumb, that is no major problem! All that you need do is move the actuator sufficent to keep the EXTREME bubble in the center as you turn the dish in azmuth. That will guide you to the Satellite. Then, while you are still on that Satellite, go back and readjust the mount's axis inclination (which will have changed as you turned around on a non-plumb post) to center the AXIS bubble. Don't change the Declination! Your ARC-SET keeps you from getting lost. If you happen to lose the Satellite's signal, the centered EXTREME bubble will guide you right back to it. Once you have the AXIS bubble centered, on the mount's axis, the EXTREME bubble is centered on the dish's inclination, and the signal from the extreme satellite is peaked, you are on Arc -- no matter where the support for the dish comes from.
As a check, actuate all the way over to the opposite-from-extreme Satellite and, while while watching Signal Strength (with your CANARY), gently lift (and then pull down on) the lowest part of the Dish Lip. If the Signal increases either way, you have mis-measured -- or the Feed is off-center Actuate up to ZENITH and double check the Dish slope (including front lip-to-lip) to confirm the bubble centers. Guy wire from highest, to lowest points of Dish lip, and pull the Feed to the spot of highest Signal Strength. Then actuate down to EXTREME and double check the Dish slope to confirm that bubble centers. Guy wire between what are now the highest, and lowest points of Dish lip, and pull the Feed to maximize Signal. This forces the Feed into the "sweet spot" of the Focal Cloud.
The ARC-SET comes apart into two, or three, of
its component sections, for mount designs that
are too tight to fit the entire ARC-SET into
their configuration -- or for simultaneously
watching the AXIS and EXTREME bubbles as you
trim a system on a non-plumb post. It comes
apart with 1/4 X 20 nuts and bolts. They are
just the size which you use to secure LNAs to
feed, etc. -- so if you ever need spares to finish
up a job right, without going all the way back,
you can borrow them from your ARC-SET. (It's
sort of like always having water-proof matches).
ARC-SETs are cast of virtually indestructable
Poly-Carbonate, and have very strong (up to 7-G's) magnets along both edges.
The ARC-SET's transparent body allows you to see the bubbles from virtually any vantage point (for alignment of Dishes which are in creatively inconvenient locations). There are transverse bubble vials fixed in each end to guide you in measuring the steepest slope angle of any inclined surface. Your ARC-SET can be pre-set for your 50-mile territory, based on our computer's "Optimum 'Polar' Mount Analysis". You can easily re-set it for alternative locations. Loosen the slotted screws to change its settings. With the screws loosened, the adjustable level vials turn easily. Put your ARC-SET on a trustworthy "Mother Dish", in the alternative location, that is satisfactorily on ARC (with its Feed properly laterally focused), center the AXIS, then ZENITH, and finally the EXTREME bubbles, and tighten the slotted screws (they go metal to matal, to lock the bubbles firmly without risk of pulling out threads). Your ARC-SET will duplicate that "Mother Dish" exactly and within a 50-mile radius, it will put all the new Dishes on the Arc just like it. Be sure to set it back, from one of your previously set local Dishes, when you return home.
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