Sequoia Aircraft Corporation F.8L Falco, Construction Manual

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F.8L Falco Construction Manual 14–3 Revision 4, March 1, 2002
VHF Navigation Antenna Installation
See Drawings No. 160 and 161. The VHF navigation antenna is a nearly-identical mirror image
of the No. 2 COM antenna, but in the right wing. The elements are run parallel to the wing spar
to the ribs at stations No. 9 and 12, and instead of angling diagonally aft-and-down the elements
are brought directly aft so that the entire antenna is horizontal. Navigation radio waves are
horizontally polarized, so the ideal is to have the entire antenna exactly parallel with the fuselage
W.L. 0. Details of the installation of this antenna are shown in Chapter 24 “Wing Assembly”.
Note on Drawing No. 161 that the length of the elements for the NAV antenna is 22.8” for each
element.
The coaxial cable should be run at right angles to the elements forward to the wing leading edge
strip and then along the leading edge strip to the cockpit and the instrument panel. See “special
consideration in wiring” if wing tip strobes are used.
If one NAV radio is used, the coaxial cable may be run directly to the radio. If two NAV radios
are used, the signal is split at the instrument panel into two equal parts with a RST-514 NAV
splitter to feed two VHF VOR-LOC receivers, plus a separate glideslope output. If desired, a
second glide slope output may be added later by splitting this glideslope output.
Note: With all other things being equal, it is usually preferable to install two separate
navigation antennas since the signal is weakened slightly by the splitter. The engineer
who designed this system considered the possibility of installing two navigation antennas
and concluded that the use of one antenna with a splitter was superior to the use of two
antennas, since more signal was lost to the resistance of the extra length of the coaxial
cable to the tail of the airplane than was lost to the splitter. Any builder determined to
experiment with a second NAV antenna should purchase the materials for an extra
antenna and install it in the stabilizer.
Materials required:
1 RST Ferrite-foil Antenna Kit
22’ RG58 Coaxial Cable (includes 3-1/2’ extra)
1 RST-514 Splitter
4 UG88 (male) BNC Connector
Marker Beacon Antenna Installation
See Drawings No. 160 and 161. The marker beacon antenna is a ferrite-foil antenna similar in
construction to the NAV and COM antennas described above. This antenna also has two
elements, each 34.3” long, installed in the bottom aft section of the fuselage. The center of the
antenna is about 70mm forward of station No. 11. The elements of the antenna are installed on
the bottom center longeron. Due to the nature of the marker beacon signal (blasting at the
airplane from below at close range) it is completely acceptable to run the elements “up and over”
the fuselage frames.
As with the other ferrite-foil antennas, the elements, ferrite balun assembly, solder joints and
coaxial cable must be securely fastened with epoxy and fiberglass cloth.
The coaxial cable should be run at right angles to the antenna elements along the fuselage skin up
to the right side longeron and then routed forward with the cable for the No. 1 COM antenna.
The coaxial cable will require one UG88 and one UG89 BNC cable connector at frame No. 8.