Here's the outcome from my posting of last week
regarding my Prosistel 2051d rotor that refused to rotate.
With the able assistance of John Crovelli, W2GD, we
first confirmed that the motor was operable in situ. The rotor was then
removed from its perch and brought to ground level. The motor housing
was then removed and set aside. The DC motor was then carefully removed
from the gear box housing and revealed that the coupling collar joining
the motor drive shaft and the input shaft of the worm gear were held in
place by a key and a tiny roll pin. Upon inspection the roll pin had
been sheared and therefore the motor was free spinning. There was no
indication as to why the pin had failed. A new pin was obtained at the
local hardware emporium and pressed into place. We decided to reseal the
motor housing to the gearbox by using matching Blue Permatex RTV. The
rotor was then tested and re-calibrated in shack using the Green Heron
RT-21 utility program to get the indicator pot in the 2051 into proper
range. W2GD then replaced the unit in the tower, manually reset the
antenna to North (including compensating for declination) and did a
final test.
The upshot of this experience is that this rotor can
fail but sustain no serious damage to the gear train due to a single
roll pin, total cost for parts, 37 cents. My thanks to W2GD for his able
work.
Bill Nicosia, W2ZKX (WB2ZKX)
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