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RC4000 ACU Boardset
Chapter 2
Hardware
2.2.3 Fluxgate Compass
The optional fluxgate compass unit (RC4000FG) should be placed on the roof of the vehicle away from
ferrous metals, electric motors, and any equipment that generates magnetic fields such as air
conditioners, generators, and traveling wave tube (TWT) amplifiers. Experience has shown that the
fluxgate performs best when mounted as high as possible on the vehicle. The fluxgate compass must be
mounted in an upright position.
Some manufacturers position the compass on the mount so that the compass may be lifted well above
the top of the vehicle. If the compass is attached to the mount, the compass configuration item (3.3.1.2.1)
must be set to the "antenna mounted" value.
The RC4000 uses the fluxgate to determine the true heading of the mount's azimuth centerline (0.0
degrees azimuth). If the compass is not aligned in the direction of the azimuth centerline, that difference
must be described in the azimuth offset configuration item (3.3.1.2.3). Some operators prefer to mount
the compass pointing forward on the vehicle. If the mount faces rearward, an azimuth offset of 180
degrees would need to be input.
Refer to the drawing of the fluxgate enclosure to verify the proper orientation of the fluxgate. NOTE: An
un-housed version of the compass is available for use in a user-designed enclosure.
The Fluxgate Compass box may be either bracket mounted or flush mounted. Without the bracket it may
be attached to a flat surface by four 10-32 screws from inside or outside the box through the four corner
holes shown in the FRONT view diagram above. When using the bracket mount, it may be mounted with
four 1/4 inch bolts using the holes shown in the bottom view of the bracket in the above diagram. The
cable may be routed through either hole in the bracket. The circuit board may also be removed from the
housing or an un-housed model is available on order for custom installations.
The following method may be used to determine the best location for the compass.
Park the vehicle in a location that is away from large metal objects or sources of magnetic fields. NOTE:
for best results, the vehicle should be parked facing in an easterly or westerly direction. The
vehicle's generator should be running, as well as all electrical equipment on the vehicle that generates
magnetic fields.
Stand on the roof of the vehicle with a standard magnetic compass. Slowly lower the compass to the
proposed fluxgate mounting location on the vehicle without changing the orientation (or heading) of the
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