[amsat-bb] G5500 Rotor Drift Issue

Mark Spencer mspencer at hughes.net
Mon Jul 13 11:42:50 PDT 2009

There have been a couple of recent posts about a G5500 voltage drift issue
and some solutions.  I'd like to thank those gentlemen for the posts and the
solutions.  I am in a unique position to be able to work with nine G5500
rotors side-by-side in preparation for the Teachers Institute II that I will
hold at the end of the week.  I noticed the same warm-up/calibration issue
mentioned in the posts.  I discovered that it took on average 10 minutes of
warm up time for the voltage to stabilize, and this voltage is the reference
on which the antenna position indications are based.  The difference between
the cold start and warm up position was around 10 degrees for AZ and 4
degrees for EL.  Minor but irritating.  I thought I'd try the easiest
solution suggested first (changing the output cap on the regulator to .1uF)
before I tried the more dramatic solution of changing out the voltage
regulator.  I simply tack soldered the .1uF cap on the exposed leads of the
existing .01uF cap, and it worked like a charm.  All nine rotor controllers
fire up at 6.12 volts and hold that voltage throughout the operation of the
rotor.  This sure will make instruction of rotor setup and calibration a
heck of a lot easier.  Thanks for the suggests.


Mark Spencer, WA8SME

ARRL-The national association for Amateur Radio

Education and Technology Program Coordinator

mspencer at arrl.org




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