30
Figure 2
Encoder Mode Jumpering
JP3
JP3 is included to facilitate any future firmware updates. Instruc-
tions for this procedure will accompany any updates issued. Header
connector J5 is used only for initial factory programming of the 720.
CONNECTING THE MODEL 720
IMPORTANT:
The 720 encoder must be properly configured for
the desired operating mode: sidechain or loop-through. Consult
Figure 2 to confirm that the encoder circuit board is properly
jumpered before connecting the Model 720 to other air-chain equip-
ment.
ALSO:
Be sure that encoder firmware has been programmed ac-
cording to the instructions in Section III.
Sidechain Mode
(Preferred)
Using a BNC
adapter at the composite/MPX output of the stereo
generator, connect one side of the
directly to a wideband (com-
posite/MPX) input of the FM exciter and the other side to the
PILOT
OR MPX INPUT
of the Model 720 as shown in Figure 3. This is only
a bridging sync connection with the circuit board jumpered for
sidechain operation and does not affect the composite/MPX signal.
Using a Separate
Sync Source
If the stereo generator has a dedicated 19kHz RDS sync output, you
may
connect this to the encoder
PILOT OR MPX INPUT
for sidechain
operation. We do not recommend this, however, as this output may
not have an accurate phase relationship with the stereo pilot in the
composite/MPX output signal.
Cable the
RDS OR MPX OUTPUT
of the encoder to a second wide-
band (subcarrier) input of the FM exciter.
Sidechain
Mode
(RDS ONLY)
Loop-Through
Mode
(MPX ON)
K1
JP1
R7
LOOP/SIDE
MPX/RDS
OUTPUT
R8
IC4
