MOD U LA TOR UNIT
14
A block diagram of the Modulator Unit is shown in
Figure 6c
, below.
15
The modulator unit comprises chassis CTX-A248 and
PCB CTX-A247. This equipment utilises a line type
modulator circuit where the Pulse Forming Network (PFN)
capacitors are charged to double the HT supply by the
resonance of the charging choke with the PFN capacitance.
The line impedance is matched to the magnetron impedance
by the pulse transformer.
16
The modulator circuit comprises a Charging Silicon
Controlled Rectifier (SCR) CSR1, Charging Choke L5,
Saturable Reactor SL1, Pulse Forming Network, Pulse
Transformer T4, Discharge SCR CSR2, and “Tail Biter” SL2
which is used for short pulses.
May 01
7c.6
Original
KH 2020
Chap 7c
MP RELAY
(FROM CONTROL
BOARD)
LP RELAY
(FROM CONTROL
BOARD)
DUMMY TRIGGER
(FROM CONTROL
BOARD)
HEATER TURNDOWN.
(FROM CONTROL
BOARD)
CSR1 TRIGGER
(FROM CONTROL
BOARD)
CSR2 TRIGGER
(FROM CONTROL
BOARD)
Rx TRIGGER
(TO CONTROL
BOARD)
-150 V
(TO CONTROL
BOARD)
MON -ve VOLTAGE
(TO CONTROL
BOARD)
FROM
POWER UNIT
-350 V
TX MON
SUPPLY
HV
MONITOR
S1
RELAY
COIL
RELAY
COIL
RELAY
HEATER
TURN DOWN
CHARGE
TRIGGER
TRANSFORMER
T3
CHARGE
CSR1
CHARGING
CHOKE
L5
BLOCKING
DIODE
D7
HOLD OFF
REACTOR
SL1
DISCHARGE
CSR2 &
PRIMING
CIRCUIT
DISCHARGE
TR2
TRANSFORMER
SYNC PULSE
TRANSFORMER
T1
SYNC PULSE
OR GATE
D4, D5
PULSE FORMING
NETWORK AND
RELAYS
L1, L2, L3,
C1 TO C6
SHORT PULSE
TAILBITER
SL2
PULSE
TRANSFORMER
MAGNETRON
OVERSWING
NETWORK &
COMPENSATING
CAPACITORS
HEATER
RFI
FILTER L4
HEATER
MONITOR
R5
HEATER
TURNDOWN
RELAY &
RESISTOR
RLC, R4
DC HEATERS
FROM POWER UNIT
HEATER I MONITOR
MAGNETRON LEADS
SYNC PULSE TO DISPLAY
CD-3823
Figure 6c - Modulator Unit (A247/248): Block Diagram
Summary of Contents for Kelvin Hughes Nucleus 3 5000 Series
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