Cessna 172P Pilot's Operating Handbook And Flight Manual 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