[amsat-bb] Re: inquiry about homebrew az-el systems

[Samudra Haque]

I would like to clarify: this antenna project is going to be handled by
others ham operators who have contacted me. Where possible, I am
contributing some hardware/mechanical parts that I have in stock. The work
for the antenna is not for my Ph.D program. As I mentioned, it is for the
K3GWU project which will go on in parallel, and there are others at GWU who
will be involved. I have donated a lot of equipment to the K3GWU station,
and that can go on to connect with an antenna when ready.

On the other hand, the ECE dept and MAE dept has resources (motors, gears)
that they want to throw away ... and that they *have* to junk at some time
after 5-10 years.



On Sun, Feb 24, 2013 at 10:43 PM, Daniel Schultz <n8fgv at usa.net> wrote:

> Samudra,
>
> Most of us could probably cobble together some sort of one-of-a-kind design
> using surplus motors and gears from Skycraft or other sources. Making a
> design
> that is reproducible and publishable, made from parts and components that
> will
> be available in quantity a year or two or three from now is another matter.
>
> I have experience making various antenna kludges for use on field day, with
> door hinges as elevation bearings, and ropes, pulleys and threaded rod as
> actuators. Everything but the motors came from Home Depot (but the small
> electric screwdrivers that they sell there could make great gear
> motors...) I
> never had any intention of leaving it up all year long or operating it
> unattended on a roof top. My design worked OK when the air was calm but the
> slightest breeze would back-drive the motors and blow it all over the
> place.
> When antennas start acting as sails in the wind, you need strong motors and
> big gear ratios, probably with brakes. You might perhaps take a look at the
> AlfaSpid design, which uses automobile windshield wiper motors to drive
> really
> big worm gears.
>
> Practically speaking, you will need a better workshop than just a grinder,
> a
> drill, a saw and a few hand tools. A lathe and a small bench-top milling
> machine are essential to any serious metal worker. You might be able to
> find
> these at a local "maker" shop in your town if there is one, or look at
> www.littlemachineshop.com, $1500 should get you a basic bench top machine
> shop, about the cost of an all mode satellite radio.
>
> Finally, Samudra, as a graduate student working on your PhD, is this really
> the best use of your time? In the end, that is the reason why most hams
> end up
> writing a check and buying a ready made rotor system, so they can get on to
> doing other things in their hobby and their life.
>
> 73
> Dan Schultz, N8FGV
>
>