Ground Wires
Lack of Power
Most operational difficulties with rotators are
traceable to broken, shorted, grounded or
miswired control cables. Time spent on
assembling, routing and protecting the control
cable will lead to a long trouble-free rotator life.
Unintentional grounds on cable leads can burn
out the line fuse in the DCU-1 control box or
burn out the potentiometer in the rotator. If pin
#3 or pin #7 is grounded, it shorts out part of the
potentiometer so that as rotation progresses to the
other end, the full DC voltage is applied across a
decreasing portion until current becomes so high
that the potentiometer or the voltage regulator
burns cut. Note also that any grounds may put an
overload on the power transformer which could
cause the line fuse to blow.
Antenna Motion
Frequently the slight motion of the antenna array
in gusts of wind is due more to the natural
flexing of the elements and mast than to actual
play in the rotator mechanism. A slight amount
of "play" is built into the rotator to avoid binding
due to environmental changes.
If the antenna rotation is slow or sluggish or hard
to start, check for proper voltages on pins #2,5,
and 6. (See Table 4) If the voltages are correct,
the 130 - 156 MFD capacitor may be old. If your
unit is more than 5 years old, try replacing this
capacitor. Also, if your cable run is over 200 feet,
make sure that you are using the proper wire size.
See Table 2. For cable runs over 300 feet, you
may wish to move the motor capacitor to the
tower. This allows you to run only 6 wires from
the control to the rotator, so that you can reduce
wire resistance by doubling up wires or using
If the electrical circuit is working, then check for
mechanical problems. Look for mast binding or
thrust bearing misalignment if you have ex-
perienced strong winds recently. If the
temperature is less than -30 deg. F ( -34 deg. C ),
the rotator will be very sluggish or may not run at
all! This is normal. Do not try to rotate with the
DCU-1 control if temperatures are below -30 deg.
F ! Older models of HAM-M, 11, 111, IV and
T2X rotators may be very sluggish at
temperatures less than 0 degrees F.
If the antenna actually rotates in high winds, this
is usually just the mast slipping in the rotator or
the antenna slipping on the mast. For large
antennas, it is often necessary to drill a 5/16"
hole through the rotator clamping plate and mast
and pin them together with the bolt provided.
Also, if possible, pin the antenna to the mast with
appropriate hardware. If slipping is suspected,
return the rotator to an end of rotation limit and
visually check antenna alignment.