User Manual

2. Amplifier Control Circuit board Assembly 30C1829G2: Figures 1 and 2.
There are seven connectors on the Control circuit board. These connectors
perform the following functions:
J2 connects elsewhere in the amplifier, such as the thermal switch, relay, and to
the 50 ì A meter.
J3 connects to the external interlocks.
J4 interconnects with J3 of the Metering board.
The transmitter interlock chain begins with the +12V at K1-7. When K1 is set ON
by energizing its coil K1-1, contacts 7 and 12 close and contacts 7 and 10 open,
turning off the LED inside the OFF button S4. The +12V from closed contact 7-12
lights the LED inside the ON button S3 and lights the optodiode in U3D, which
provides a logical active low out of its pin 10 for a remote control status
interface. This status signal simply tells the remote control through J5-6 that
the transmitter was instructed to be ON, nothing more.
The +12V from contact 7-12 also comes out of the board on J3-5, which is one side
of the EXT 1 interlock. EXT 1 in larger transmitters is often used with a fire
alarm system to stop all blowers, and in lower power transmitters it is still
worthwhile that a normally closed fire alarm contact be connected to EXT 1
because the fan(s) in the transmitter could cause enough air currents in the
transmitter room to fan the flames.
When the EXT 1 interlock is closed and the +12V appears on J3-4, the +12V is now
at DS5 (marked EXT 1) and the optodiode of U3C which both light up to say EXT 1
is closed. The active low from U3C pin 11 informs the remote control via J5-14
that EXT 1 interlock is closed.
The +12V now is applied to J2-8 which connects to a normally closed contact in a
thermostat that responds to the temperature of the RF power amplifier. If a
cooling fan should stop and the amplifier should overheat, this contact will open
and prevent the +12V from appearing at J2-3. This of course breaks the chain and
removes the 12V from the solenoid of the power supply contactor.
Assuming the thermostat is cool, DS4 and the optodiode in U3B are lighted,
confirming TEMP is okay. The logical active low out of U3B pin 14 informs the
remote control of this fact through J5-7.
Assuming the thermostat is closed, the +12V next appears at J3-3, which is EXT 2
interlock. This is the place where RF patch panel link contacts or coaxial
switch auxiliary contacts, and/or dummy load thermostat contacts would be
connected so that the transmitter can only be ON when valid RF paths are present,