[NLRS] Elevation rotators for small stuff

[Dr. Gerald N. Johnson]

On 9/5/2013 9:32 AM, Doug Reed wrote:
>
>
> The Surplus Center link that Jerry left has some 12v linear seat
> adjusters for $15 but they only provide 2.25" of travel. That would be
> enough for elevation control but provide only minimal adjustment for
> azimuth. The U100 would certainly be easier to use for azimuth but
> there is still the issue of mechanical slop.

They do have linear actuators with much more travel, out to a couple 
feet but if they have a few hundred pounds load rating they are fairly 
expensive.

Hydraulic or air cylinders would do linear also.

For azimuth with a linear actuator and one added link it is possible to 
get more than 180 degrees rotation without bending the linear actuator 
around the mast. See how this back hoe bucket is curled nearly 270 
degrees from its dig down position with just the links at the pivot and 
the single cylinder along the outside of the stick.
static.ddmcdn.com/gif/backhoe-loader-sideview.jpg

Illustrated very vividly in the video:
www.youtube.com/watch?v=MXhhXXsxSfE
made for kids but shows the full range of bucket curl in the each bucket 
load dumped. Best watched with the sound off.
>
> I keep thinking of the 10GHz&  up contest, not the other contests. I
> was thinking of turning the dish(es) down to horizontal to reduce wind
> load when traveling. That means another rotating joint and something
> to power it. Another U100 would work. At Central States several years
> ago, one of the rovers used a spring-loaded frame to provide tension
> that the elevation arm worked against. It was pulled by a winch cable.
> But none of that will work if it is nestled in between other rover
> antennas.
9SNR lays his 10 G dish down for traveling, turns the car to rotate all 
the antennas.
>
> You want simple, then put a cheap video camera on the dish and use
> that to adjust AZ-EL. It will at least make it fairly simple to adjust
> elevation for the horizon and point to the same stand of trees where
> your compass or GPS says to go. Nobody else seems to like the idea of
> an electronic compass on the dish, but it would at least let you
> adjust plus or minus from a bearing once you find the first target.
>
> Figuring out accurate azimuth has always been the main problem. I like
> the "get bearing from waypoint" mode on a handheld GPS. Or you can
> note the bearing as you drive the car the on the last straight away
> before you park. Point in that direction then note the compass bearing
> and adjust as needed. The video camera on the dish might also help use
> sun shadow to calibrate the azimuth bearing.

In the plains of Iowa and SW Minnesota, the majority of country roads 
are on section lines which are as accurate north and south or east and 
west as they could survey 160 years ago. Last September working with GSP 
and with every planned stop on a road on or parallel to a section line 
it was easy to predict paths to the hill and they took little 
refinement. On could take the handheld GPS and walk 100 feet, maybe 100 
yards in a straight line to get the GPS to compute a bearing after 
parking. But if one avoids being confused by receiver AGC, peaking on a 
beacon seems to work even when fairly much disoriented. In some 
situations it would be best to turn the AGC OFF so the signal peak can 
be heard. Many a receiver's LCD display s-meter is useless for fine peaking.

Sun shadow is different every day and somewhat dependent on the local 
slope so it takes more data to be very precise.

73, Jerry, K0CQ
>
> Since I'm not building one, I'll just wait to see what works. :-)
>
> 73, Doug Reed, N0NAS.
> ______________________________________________________________
>