Checking
procedure
(
I
)
Connect
other
antenna
Change
the receiving antenna to other antenna
placed
at the
position
as
far
as
possible
from
the transmitting antenna
which
interferes
the
receiver.
(2)
When
the antenna
multi-coupler
is
used, connect the antenna directly to the receiver.
(3)
When
the
arrester-diode
is mounted
in
the antenna
system,
add the
same
diodes
in series
so
as to increase
the
number of
the
diodes.
(See paragraph
6.3.5.)
When
the interference
does not disappear even
after
checking
with
the above
procedures,
no countermeasure is effective.
Thus,
leave the record
for the
degree of interference,
combination of
the
transmitting frequency
and receiving
frequency for future conve-
nience, and avoid
such a combination of
frequencies with the
strong
interference. The
receiver itself
is designed so
as
to
amplify
enough even a signal
of I
pV,
so
that
it can
not
be avoided
that
the some extent of interference occllrs in
the
simultaneous
transmis-
sion and reception
when antenna installation
places
cannot be separated enough
in
the
small
ship,
etc.
6.3.5
Intermodulation
While
receiving
some
frequency, it sometimes
happen to
hear
such several
signal
as
cannot
be
radiated by
that frequency.
This
phenomenon
is
caused by intermodulation.
Checking
procedure
(1)
When the antenna
multi-coupler is
connected to the
antenna
for receiver, connect
the
antenna directly
to
the receiver.
If
the
above
phenomenon
disappears, it
can
be
considered
that
the intermodulation
arises at the
antenna
multi-coupler.
(2)
When the
phenomenon
does not
disappear
even
though the
receiver is connected
to the
antenna
directly,
check whether arrester-diode
is inserted on
the way of
the
feeder
line,
or not.
If
inserted,
remove that arrester-diode and
then
receive the
signal
(at
this time,
do not operate the
transmitter).
If the
phenomenon
disappears by
removing the arrester-diode,
add arrester-diodes
more
or
replace
them
with other type
protecting
element.
(3)
When
the
phenomenon
does
not
disappear
even
though the
receiver
is connected
to the
antenna directly and the arrester-diodes are removed,
this
is
caused by
the
characteristics
of the receiver.
At
first, remove
the arrester-diodes CD22 to
CD27
mounted on the
input
filter
circuit
(CFL-I84).
When the
phenomenon
does
not
disappear
still
now,
Y
I
|
?_._
r--'---r
VT
++
YT
++
?
,7+7
-23
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