Transmitter Control/Monitor Interface (A5PC1J3)
Jack – Pin #
Function
2
6
16
range (
3dB). At the same time, the low output of AND gate U4C is passed to
pin J10-18 through resistor R23 and on to front panel AGC ACTIVE LED control
transistor PC3Q6. Since the voltage at PC3J1-18 is low, PC3Q6 will not conduct
and PC3DS6 will turn off indicating an inactive output AGC. If the voltage was
high, transistor PC3Q6 would forward bias causing the LED to turn on, indicating
the output AGC was active.
J4 – 3
AMP BIAS CONTROL: This voltage is generated by AND gate U2C and
forwarded to switching FETs A5PC1Q1/Q2 which activate or deactivate the
power supplies (A3PS1/PS2) contained within the 500W UHF Power Amplifier
drawer A3. Power Supply activation requires that UHF Synthesizer A2 be locked
(J2-8 high) producing a high at U1A-3, that the OPERATE/STANDBY lines be
open (J5-1 and J10-7 high) creating a high at U1D-11 and that the VIDEO
SENSE line (J4-5) provides a high to U2C-10. Under these conditions the high
furnished at U2C-8 will activate amplifier drawer A3. If any of the above
conditions change creating a logic low at J2-8, J5-1, J10-7 (OPERATE/
STANDBY switch PC3S1) or J4-5, then the 500W UHF Power Amplifier drawer
will be shut down.
J4 – 5
VIDEO SENSE: A high/low indication for the presence or absence of video pro-
gramming is delivered to this input from the Video Detector Switch (VDS) TALLY
jack. With video present at INPUT A9-A, an open is sent from A9J1-NO to J4-5
via A5PC1J8-1 and A5PC1J3-5 placing a high on U2C-10. If a loss of video
occurs, a ground appears at A9J1-NO forcing U2C low at pins 10 & 6 which
deactivates power supplies A3PS1/PS2 in the 500W UHF Power Amplifier
drawer.
J4 – 8
GND: Ground to A5PC1J3-8
Display/Monitor Interface (PC3J1)
Jack – Pin #
Function
J10 – 1
+5V: From J3-4 to PC3J1-1
J10 – 2
GND: Ground to PC3J1-2
J10 – 3
15V: From J3-3 to PC3J1-3
J10 – 5
+15V: From J3-5 to PC3J1-5
J10 – 7
OPERATE/STANDBY: An open or ground is brought in on this pin from the front
panel OPERATE/STANDBY switch PC3S1 via PC3J1-7 to place the Exciter/
transmitter in operate (switch in) or standby (switch out) while illuminating or
extinguishing OPERATE indicator PC3DS7. If the incoming logic level is high
and assuming all other gates are high, pin U1D-11 will remain at 5V keeping the
AMP BIAS CONTROL (J4-3) level high to activate the 500W UHF Power
Amplifier drawer. Simultaneously, the output of U8A and voltage at J10-21
remain normal through LEVEL ADJUST PC3R16, PC3J1-23, J10-23, J8-7, and
PC1-7 causing buffer PC1U9 to set IF input attenuator PC1CR7/CR8 at its
appropriate value. If OPERATE/STANDBY switch PC3S1 supplies a ground to