Modu la tor Con trol Cir cuit
6
A block diagram of the Modulator Control circuit is
shown in Figure 2a, below.
7
The modulator control circuit monitors the PULSE
LENGTH, STANDBY and MUTE control signals from
the display, and senses the AZIMUTH pulses which indicate
Antenna rotation. The circuit generates modulator triggers.
8
Three LEDs, la27V, TX READY and TUNE,
and an antenna motor relay (which can be activated
when Switch S4 is closed) are mounted on the PCB.
9
Power supplies of +15V, +27V, +24V and +8.5V are
supplied from the Power Unit. Supplies for other areas
of the transmitter are generated on the PCB.
Modu la tor Cir cuit
10
A block diagram of the Modulator is shown in Figure
3a.
11
The modulator uses a line type circuit whose
capacitors in the PFN are charged to double the HT
supply. The line impedance is matched to the magnetron
impedance by the pulse transformer.
Sync Pulse Out put
12
One low impedance sync pulse output is produced by
the modulator. This is split to provide three output
connections from the downmast transceiver case.
May 01
7a.2
Original
KH 2020
Chap 7a
JITTER
CONTROL OFF
Tx DISABLE
IC10B
AZIMUTH
DETECT TR21
& IC16A
FAST CLOCK
3000Hz IC14A
MOD TRIG.
OUTPUT
SLOW CLOCK
42Hz IC14B
CHARGING
DELAY IC16
HT & TRIG.
SHUT-DOWN
IC10A, IC11
& IC1C
AERIAL RELAY
DRIVER TR2
& RLN
LATCH PRF
LATCH PFN
RELAYS IC4
PFN RELAY
DRIVERS
PRF
GENERATOR
INPUT CHANGE
DETECT
IC2, IC28
PRE-PULSE
EXT. SYNC PCB
PULSE LENGTH
DETECT
IC1, IC3 & IC13
INSTALLATION
PRF SWITCHES
IC4 & IC5
AERIAL RELAY
RLB
SYNC AMP X3
TR10, TR11
& TR12
SYNC ADJUST
RV1
IC7B, TR7, 9
Tx
READY
1, 5, OR 3
(X OR S)
MINUTE TIMER
IC9
FAST/SLOW
DETECTOR
IC17 & IC11
TIMER
HOLD-ON
CIRCUIT
LATCH
ENABLE
PRE-PULSE
EXTERNAL
SYNC PCB
MUTE
AZIMUTH
RUN/STANDBY
MEDIUM PULSE
LONG PULSE
CD-2182
CSR2 TRIGGER
CHARGE TRIGGER
SHUT-DOWN CIRCUIT
LK16
SYNC 1
SYNC 2
SYNC 3
Tx READY
S4
LK3
1
1
2
X
1
2
Figure 2a - Modulator Control Block Diagram
Summary of Contents for Kelvin Hughes Nucleus 3 5000 Series
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