Motorola R-2400 Operator's Manual page 44

Normally, repairing or replacing
cables
solves the
prob-
lem without retuning. check the
duplexer manufac-
turer's data
sheets
to
determine proper installation.
l.
connect the
service
monitor
to
the
repeater/du-
plexer under test,
as
shown
in figure
s.14. Connect
the "RF
Inlout" to
the
duplexer's antenna port
through an RF tap-off isolating
device.
CAUTION: To
prevent RF overload
into
the generator,
provide sufficient isolation
between the
tap-off
and
the
straight-through feed. For example, a 1000w transmit-
ter requires
50
dB isolation.
2.
connect the "Yert/SINAD/Dist" input
to
the
re-
ceiver speaker connection. Disconnect
the
cable
from the "RF rn/Out" to
prevent the transmitter
from
keying up on
repeat.
3.
set
left LCD to "Dev", "Function" to "Gen",
and
enter the receiver frequency.
4.
Set
the attenuator to
-60 dB and the "RF vernier"
control to mid-range.
5.
Adjust
the
"l
KHzLvl"
control to
3.0
kHz DEV
on
the LCD.
6.
Reconnect the cable
from "RF Inlout" to
the
RF
tap-off
and enable the transmitter to key-up. For
ex-
ample,
it
may be
necessary
to
provide 0.7s KHz
PL/DPL
deviation for
a
PL/DPL
accessed repeater.
7. with
this generated signal
introduced to
the RF tap-
off,
adjust the
signal
generator
Step attenuator
and
the "RF vernier"
to the
12
dB SINAD
level
as in-
dicated on the
LCD.
Note the generator RF
Level
on the right.
8.
Disable the transmitter from
key-up. Readjust
the
signal generator
to
obtain
12
dB SINAD
again.
Note the generator RF
level.
9. The
difference between the RF level
for lz
dB
SINAD with the transmitter off
(step 8) and with
the
transmitter on
(step
7),
is
the amount of
system
desensitization.
10. More than 2 dB desensitization may indicate:
defective antenna
system
loose
shields
transmitter
spurs
improper or defective duplexer
cable
Check them all,
before attempting to
retune the duplexer.
\.t/
\-/
5-10
\-./