We presently operate a
Cessna TU206G and have an installation similar to what you describe.
However, the antennas (Comat model CI-177, for frequencies 148 - 174 MHz)
are not permanently mounted to the airframe. They are permanently mounted to
wing "cuffs" (a hinged, padded clamshell arrangement) that easily attach to
each wing strut before telemetry flights.
According to the logbooks for N104PS, these were
designed by W.P. Jennings & Associates, Inc. - Engineering Consultants, and
were installed under STC SA00162SE for the Cessna 206 series. I've attached
a photo that may give you an idea of how these look when mounted (that's
western Grand Canyon and the Colorado River in the background).
For a larger image, click on the small picture.
Black bands (not very visible when the antennas are on
the airplane) have been painted on each wing strut to help us mount the
cuffs in the same location each time. Three bolts fasten the cuff halves to
each other and hold it securely in place during flight. A small length of
coaxial cable (visible in the photo) connects the antenna to a BNC connector
on the underside of the wing. Coax runs from the BNC connector through the
wing to the cabin and terminates in a panel above the fuel tank selector
(just below the rudder trim). The biologist-observer plug their gadgets into
the system at that point.
Apparently because of differences in routing the coax
in each wing, we estimate that the right wing has at least one foot more of
cable than the left wing. This causes a difference in signal strength but
we've gotten used to it; encourage your installer to make the cables in each
wing as equal in length as possible.
My partner upstream (Tug Kangus at Glen Canyon
National Recreation Area) had a new 206 wired last summer, and the contract
specs read something like: "Two coaxial cables (one on each side of the
aircraft), terminated in BNC connectors, shall be furnished and installed
for the temporary installation of strut-mounted tracking antennas. The
cables shall be routed from a central location in the cockpit, through the
wings, to locations near the strut/wing attachment points. The installation
shall be completed in such a manner as to provide a convenient connection
point when the antennas are installed, yet present an uncluttered appearance
when the antennas are not installed."
I believe Yingling Aviation in Wichita or one of their
subcontractors did the install. Please let us know if we can help with
anything else or if you need additional photos. --Mike Ebersole
Michael J. Ebersole
Grand Canyon National Park
P.O. Box 129
Grand Canyon AZ 86023-0129
Telephone: (928) 638-7878
FAX: (928) 638-3464
Email: Michael_Ebersole@nps.gov
Website:
