JRC NDR-91 User Manual

6.3 TROUBLESHOOTING
Troubles
may happen
sometimes
while
using
a receiver
for
a
long
p.rioO.
Some
troubles
are due
to the receiver
itself,
but
some of
them
may
be caused
by reasons
other
than
the
receiver.
'Ihus,
even
if
the receiver
is under
a trouble
conclition,
do not
conclude
that the
trouble
is
due to the receiver
without
checking
the cause
by
yourself.
Check
whether
the
trouble
is
due
to the receiver
itself or
due
to
the
external
problems
according
to the
trouble-
shooting befbre
contacting
with
JRC
or JRC's
sales
agent or
service
station.
The
inspecting
methods fbr
typical
troubles
are
described
below.
6.3.1
Decline
of
the
sensitivity
The
word
"Sensitivity"
is used
ambiguously
among
users.
In
this
section,
the
decline
of
sensitivity means
not only
that the
sound
volume
is not
large
but
also
that
S/N
of the
output
signal of the receiver
reduces.
Explanation
For
some constant high
frequency
input
signal,
the
sound
does
not
depend
on
the
performance
of the receiver.
This
depends
only
on the
gain
from
the input
stage to
the
AF
output
stage
of
the
receiver.
For
example,
"the
former
receiver
could
produce
the
sound
loudly
enough
with
RF GAIN
set to 8
graduation
and AF GAIN
to
2. But
the
present
receiver
can't
produce
the sound loudly
with
the
same
gain
settings,
unlike
the
former
receiver.
This
receiver
has very
bad
sensitivity."
This
doesn't
make
sense
at
all. The effectiveness
of RF GAIN
volume
and AF
GAIN
volume
for
the
setting
graduation
is different
among makers.
Even
in case of the
same model receivers,
there
are
some differences.
Also, even
though
the distance from
the
partner
station
and
frequency
are the
same, the
wave
strength
varies largely
depending on
ttre
year,
season,
time, etc.
Thus, in
order
to compare
the
sensitivity
of the receivers,
S/N of
the receiver
must
be compared
between
receivers
under
the
following
condition:
Connect
the same
antennas
to the receivers
to
be
compared,
and receive
the
same frequency
at the
same time,
by
setting the
speaker
sound volume
to the almost
same level.
Checking
procedure
(
1) Check whether the receiver
is
misoperated
or
not.
Check
whether ATT
is
set
to ON,
or not. Receive
the radio
wave in other
frequency
band. When
the
sensitivity
is very
bad
in the
special band,
receive
that radio
wave by
other receiver,
if
possible.
If
the
difference
is
remarkable
between
receivers
when receiving
the
same
signal in
the
same time
by the
same antenna, it
can conclude that
the
trouble
is
due to the receiver
itself. If
that
diff'erence
is not remarkable, that
is not
the
trouble
of the receiver
itself. This
difference
depends on variation
in
receivers.
(2)
When the
sensitivity
reduces
even
if the frequency
band is
changed,
start the check from
the antentra system. When
an antenna
multi-coupler
or
antenna changer
is inserted
between the antenna
and
receiver,
connect the
antenna
directly to
the receiver.
If
the
sensitivity is still bad, connect
another antenna
to the receiver.
If
the
sensitivity is
greatly
improved
when connecting
the antenna
directly to
the receiver,
check
the
cable, antenna
multi-coupler
and
antenna changer
successively.
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JRC NDR-91 Specifications

General

Brand	JRC
Model	NDR-91
Category	Receiver
Language	English