System Description Chapter 2
100 Watt High Band VHF Transmitter Chapter 2, System Description
420A, Rev. 0 2-8
loop-through connected, for composite,
stereo, audio. To use the 4.5 MHz
composite input kit, the baseband audio
can remain connected to the VHF exciter
even if the 4.5 MHz composite input kit is
used, but the baseband video must be
disconnected from J1 or J2 and the 4.5
MHz composite input connected to J1 or
J2. The baseband select command must
also be removed from J18-6 and 7.
Remote monitoring and operation of the
transmitter is provided through the jacks
(J10 and J11) on the rear of the tray.
Jack (J11) should have a dummy plug
connected to it, with a jumper connected
between pins 23 and 24, that provides
the interlock needed to operate the
transmitter. If this jumper is missing, the
transmitter will not switch to Operate. If
remote connections are made to the
transmitter, they should be made
through the plug in J11 or to J10 in the
positions noted in Table 2-7.
Note: If the optional 4.5 MHz
composite input kit is purchased, the
baseband select connects to J18,
pins 6 and 7, on the back of the tray.
The remote interface connections for the
420A transmitter are listed in Table 2-7.
These connections are made to jack
(J11), the 37-position, "D"-connector, or
to jack (J10), the 25-position, "D"-
connector, on the rear panel of the tray.
Note: Only the pins called out in
Table 2-7 are utilized in this
transmitter.
Table 2-7. Remote Interface Connections
FUNCTION REMOTE JACK/PIN
NUMBER
INTERFACE TYPE
Transmitter Enable Interlock J11-24
Transmitter Enable Interlock
Rtn
J11-23
J11-24 and 23 must be
jumpered together for
normal operation; (1176-
1038) jumper jack
should be used.
Remote Control Commands
Transmitter Standby
(Disable)
J11-22
Contact closure
Transmitter
Standby/Operate Rtn
J11-21
Transmitter Operate
(Enable)
J11-20
Contact closure
Transmitter Manual J11-9 Contact closure
Transmitter Auto/Manual
Rtn
J11-36
Transmitter Auto J11-8 Contact closure
Power Level Raise (optional) J10-11 Contact closure
Pwr Lvl Raise/Lower Rtn
(optional)
J10-13
Power Level Lower
(optional)
J10-12
Contact closure