G-858BP Backpack Mag
Operators Manual
Adjusting the Pack Frame
The first time the pack frame is assembled and used, it will be necessary to adjust it for the
individual user. This may require a second person to observe and make adjustments to the fit while the
system is worn by the survey crew member. The pack frame is a professional grade frame with several
different strap adjustments available. In addition, the frame itself is made of telescoping vertical poles that
allow the frame to be extended or compressed for different sized individuals.
The pack frame commercial hardware has been replaced with brass and aluminum parts, removing
all ferromagnetic components to keep the system magnetic self-signature to a minimum, thus reducing
heading error and other platform noise. Never replace hardware with untested bolts, nuts or rings. Always
test the hardware first by turning on the magnetometer and moving the hardware under test near the sensor.
Typical goals are to have less than 0.5nT effect at 2 feet (0.6m) from the sensor.
The brass bolts on the vertical frame poles should be adjusted such that the shoulder straps start
approximately 3 inches (7 cm) below and behind the shoulder. If the straps are too high the weight of the
pack will not be on the shoulders, remove the brass bolts and shorten the vertical poles. If the straps are too
low the straps will not adjust in the front. Then lengthen the vertical poles. See photo below for brass scew
location.
If you need to extend or compress the
pack frame, remove all 4 brass bolts and nuts
and slide the pack frame tubing into or out of
the mating tubing to get the proper height. You
may have to loosen the back support webbing
to get to the screws and to reposition the t
Reassemble the pack frame using the same
bolts and nuts. Remember that any hardwa
not supplied by Geometrics is possibly
contaminated with ferrous materials and can
cause magnetic contamination.
Figure 19 Brass Bolts for Frame Adjustment
ubing.
re
19