Spektrum SPMMSJR9 - Manual (Page 12)

Spektrum Air Module 1
Install the main receiver using the same method you would use to install a
conventional receiver in your aircraft. Typically wrap the main receiver in protective
foam and fasten it in place using rubber bands or Velcro straps. Alternately in
electric models, it’s acceptable to use thick double-sided foam tape to fasten the
main receiver in place.
Mounting the remote receiver in a slightly different place, even just two inches from
the primary receiver, gives tremendous improvements in path diversity. Essentially
each receiver sees a different RF environment and this is the key to maintaining a
solid RF link, even in aircraft that have substantial conductive materials, (i.e. larger
gas engines, carbon fiber, tuned pipes, etc.) which can attenuate the signal.
Using double-sided foam tape, (servo tape) mount the remote receiver keeping the
remote antenna at least 2 inches (51mm) away from the primary antenna. Ideally
the antennas will be oriented perpendicular to each other, however, we’ve found this
to not be critical. In airplanes, we’ve found it best to mount the remote receiver to
the side of the fuselage or in the rear turtle deck.
Installing the Receiver