Service manual

2-39
March 2000
Part No. 001-3139-502
900 MHz LOCAL OSCILLATOR SCHEMATIC
FIGURE 2-19
FOLDOUT
1
2
3
4
RF OUT
GND
GND
+13.8V IN
Y300
OCXO 1
5 MHz
J303
R340
1k
R339
10k
C297
150pF
CR301
Q300
3053
S300
INTERRUPT
SWITCH
+13.8V
1
2
3
4
RF OUT
GND
GND
+13.8V IN
Y301
OCXO 2
5 MHz
J304
R341
1k
R342
10k
C298
150pF
CR302
Q303
3053
+13.8V
R328
270
+5V
C295
.01
R318
270
+5V
+
C296
22
10
9
8
U311C
54LS00
U311A
54LS00
U311B
54LS00
1
2
3
4
5
6
2
3
13
4
1
1415
TRIG
CLR
Q
Q
TRIG
RC
U300A
74HC123
C304
150
R313
4.7k
R312
10k
+5V
2
3
13
4
1
1415
TRIG
CLR
Q
Q
TRIG
RC
U303A
74HC123
C306
150
R315
5.1k
R314
10k
+5V
10
11
13
12
9
67
TRIG
CLR
Q
Q
TRIG
RC
U303B
74HC123
C307
.47uF
R324
270k
R325
10k
+5V
9
811
12
U305A
54LS74
D
CLK
Q
Q
2
14
U312
54LS393
CLK
CLR
Q1
15
14
10
11
12
13
9
U313
55121
+5V
R332
51
L300
C315
3900
L301
C316
3900
L302
A10
J305
9
10 13
12
67
TRIG
Q
Q
RC
U300B
74HC123
C305
1000
R311
3.3k
R343
10k
+5V
TRIG
R305
10k
Q302
3053
+5V
R307
200
R306
1k
CR304
OUTPUT
FAIL
R301
10k
Q301
3053
+5V
R304
200
R302
1k
CR303
OCXO 1
FAIL
R308
10k
Q304
3053
+5V
R310
200
R309
1k
CR305
OCXO 2
FAIL
R320
10k
Q305
3053
+5V
R322
200
R321
1k
CR306
∆ F
FAIL
3
2
1
P301J301
3
2
1
P302J302
R333
1k
R334
1k
R323
1k
Q306
3057
+5V
K300
CR307
2
1
BACK PANEL
TERMINAL STRIP
ALARM OUT
ALARM RELAY
RELAY DRIVER
FAIL DETECT LOGIC
OUTPUT FAIL DETECT
49 dB VARIABLE
ATTENUATOR BOARD
1.25 MHz
RF OUTPUT
LINE DRIVER
BINARY
COUNTER
4
OCXO SELECT
OCXO 1 FAIL DETECT
OCXO 2 FAIL DETECT
∆ F DETECT
RETRIG ONE-SHOT
RETRIG ONE-SHOT
RETRIG ONE-SHOT
14
347
6
511129
1
13
PCA IN
PC2 OUT
PCP OUT
PCB IN
VCO
OUT
C/B C/A
VCO INR2R1
INH
U306
4046
+
C308
1
2∆F
R326
470k
R327
39k
PHASE-LOCKED LOOP
5
63
2
U305B
54LS74
D
CLK
Q
Q
+5V
CS
BUFFER
BUFFER
4
IN
12
2
J300
F300
4A
+
C299
220uF
+
C300
2.2uF
+13.8V
SOURCE
2
3
1
5
OUT
R300
27k
R299
100k
C301
.001uF
C303
.1uF
+
C302
47uF
+5V
SOURCE+5V REGULATOR
U299
LM2931
NOTES:
1. ALL RESISTORS ARE IN OHMS AND ALL CAPACITORS ARE IN PICOFARADS
UNLESS OTHERWISE SPECIFIED.
2. IC PINS NOT SHOWN:
IC
PIN NUMBER
+5V GND
U300, U303, U306, U313
U302, U305, U311, U312
U308, U309
16
14
8
8
7
1,4
FEEDTHROUGH CAPACITOR AND FERRITE BEADS ARE PART OF CONNECTOR
ASSEMBLY (PN 023-4406-503).
3
3
FROM BACK PANEL
J300-12
B+ IN
CR361
TO F300 PAD
(OCXO BOARD)
B+ OUT
CR362
R361
3.3
BATTERY B+ IN
BACK PANEL
TERMINAL STRIP
3
NOTE: CONNECT +12V BATTERY TO CACK PANEL TERMINAL STRIP
WITH POSITIVE (+) LEAD TO TERMINAL 3 AND NEGATIVE (-) LEAD TO
TERMINAL 2. (TERMINAL 2 IS ALREADY CONNECTED TO PC BOARD
GROUND.)