[Moon-Net] SPID RAS HR rotator - elevation angle errors

Courtney Duncan courtney.duncan.n5bf at gmail.com
Tue Nov 1 02:23:43 CET 2016

My station has an AlfaSpid RAS.  I needed 50 lbs. of counterweights to dependably rotate a 3 m. RFHamDesign dish with feed.

The only live action position counting problems I’ve had have been due to low voltage dropout when trying to rotate under-supplied.  Chatter chatter flicker and I was off five or ten degrees in both axes.

No problems related to RF transmission - 300 W. 1296 at the feed.

But, there -are- two annoying things:

1.  When power is disconnected, it loses it’s memory and goes back to 000 000 no matter where it was pointed.  This isn’t a huge problem because I run it from a battery and it’s always connected (except during maintenance…) (Which is how I can have low voltage dropout.)  The workaround is to write down where I left it every time I QRT so I can get back if something happens.  Or, if I know I’m disconnecting the controller I can just park at 000 000.  Or, worst case, can just re-calibrate.  I can eyeball horizontal and know that the edge of the house is 160 true and can eyeball within a degree of those.  After calibrating like this, when I pointed at the sun and got the shadow of the feed perfectly on the center of the dish and looked at the display it matched where the sun was supposed to be to the last degree, so I’m within one degree (at least in that quadrant).

2.  Two or three times I’ve laid down something on the mouse and had it go around TWICE to 180 and hitting the stop before I realized it was moving.  “Hey, why am I not hearing anything?”  Oh….  This is a pain and at least once has resulted in a complicated unwrap and recalibration.

But hey, if not for all this, what would be the fun?

73, Courtney, N5BF

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