Cessna 172P - Page 313

PILOT'S
OPERATING
HANDBOOK
SUPPLEMEI{T
16
cEssNA
300
NAV/COM
(TYPE
R1-38õ.A)
The Cessna 3ü) Nav/Com incorporates avariablethreshold
automatic
squelch.
U¡ith
this sguelch aystom,
you
set the threshold
level
for
auto-
matic
operation
-
t'he fr¡¡"ther clockwise
the lower the threshold
-
or the
more
seusitive tJre set.
Whenthe
signal
is
above
this
level,
it is
beard even
if
t,Le
noiee
is very olose to the signal. Below tbis
level, tbe squelch is fully
automatio
so wben the baokground
noise
is very
low, very weak signals
(that
are above
tJre noiee) a¡e'let
through.
For nomal
oparation
of
the
squelch
oircuit,
Just
tum the
equelch olootr¡wiee
until noiso ie heard
-
then
back
off slightly until
it is
quiet,
and
you
will bove automatic squelch with
the
loweet
praoüioal
tbreshold. This a{Justment
should be rechecked
periodically
during
eaoh flight to assure
optinum
reception.
All
oontrole for the Nav/Com,
exoept the sta,ndard omni
bearlng
selector (OBS)
hob ortJre optlonal
automatio radial oentertng
(AEC)
knob
located
on the
course devlation i¡dioator,
a,re mounted
on
the frontpanel
of
the ¡eceiver-tran¡mitter.
Operation and
desoription
ol
the audio
control
paneli
used
in ooujunotion wlth thtg radlo are
shown and desoribed
in
another
supplement i¡ tbis saotion.
SECT¡ON 2
LIMITATIONS
to the
airplane limitations
when
this avionic
There
is
equipment
is
no change
instaUed.
sEcTtoN
3
EMERGENCY
PROCEDURES
There
is no cha,nge
to
the airplane
emergency
procedures
when
tJris
aviouic
equipment
is
lnstalled.
However, if the
frequency readouts
fail,
the
radlo
will
remain
operational
on the last frequõncy
selected. The fre-
quency
control
should
not be moved
due to
tbe
difficulty
of
obtaining a
known
frequenoy
under
this
condition,
õ
30 May
1980