[TowerTalk] rotors, controllers, etc.

[Jim Lux]

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).