I'm not likely to be buying a rotator for myself soon (being more of
a phased array kind of guy), but, it seems that for the $1300 or more
for a top of the line ham market rotor, you could do better by buying
a controller like the Green Heron (for $550) and fairly off the shelf
motor/gearbox combinations from Grainger or McMaster Carr ($400 or
so). Sure, there's the advantage of "it's already been packaged and
integrated", but if you're up in the category where you're twisting
something big enough (like a MonstIR) to need the top of the line
rotator, you've probably already done a fair amount of system
engineering and already into the project for several tens of
thousands of dollars. A few hundred bucks for some fabrication of
the needed mounting brackets (if they don't already exist from the
mfrs), and you've got something that is not only going to be
bulletproof, but uses cheap and readily available replacement parts
(standard sized motors are available everywhere, over the counter).
Or is this just a sort of historical thing.. people started with
cobbling something together from surplus (like my grandfather's (the
original W6RMK) prop pitch rotators with polarity sensitive relays in
a bridge circuit) then TV antenna rotators that were juiced up a bit,
(all those AC split phase motor designs), etc. Certainly, if you go
out and buy a Ham N or a T2X or a whatever, there's probably
off-the-shelf bracketry to bolt it to just about every tower made and
every mast used. And, of course, you can order it from the same
place you buy your radio, coax, and antenna, which is nice. But
maybe not. There are a fair number of questions on this reflector
along the lines of "how do I fit a model X rotator in a model Y tower?"
Maybe it's the relatively recent availability of programmable
controllers (like the Green Heron)? While the mechanical fabrication
issues are pretty straight forward, rolling your own controller is a
bit of a chore (feedback loops, hunting, damping, brakes, all that
stuff), and maybe what you you get with the fancy rotator/controllers
is that someone has already done that work, so what you're really
paying for is the controller, not the mechanical part. But these
days, a programmable motion controller with a ethernet or RS232
interface is a cheap and readily available thing. The Green Heron is
a great example of a "ham tuned" UI, but there's a raft of simple
motion control widgets out there with comparable capacity (especially
if you're going only computer control and don't need a front panel).
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