Icom IC-756PRO - Pll Adjustments

4 - 2
4-2 PLL ADJUSTMENTS
REFERENCE
FREQUENCY
LPL-A LOCK
VOLTAGE
VCO-A LOCK
VOLTAGE
1LO-A
OUTPUT
LEVEL
LPL-B LOCK
VOLTAGE
VCO-B LOCK
VOLTAGE
1LO-B
OUTPUT
LEVEL
3LO
OUTPUT
LEVEL
S3LO
OUTPUT
LEVEL
ADJUSTMENT
ADJUSTMENT ADJUSTMENT CONDITION
MEASUREMENT
VALUE
POINT
UNIT LOCATION UNIT ADJUST
1
2
1
1
2
3
4
1
1
1
2
3
4
1
1
1
• Display frequency: Any
• Turn L52 on the PLL unit to 4 rota-
tion downside for presetting.
• Receiving
• Display frequency: 0.030000 MHz
• Mode : USB
• Receiving
• Display frequency
: 14.999999 MHz
• Mode : USB
• Receiving
• Display frequency
: 19.999999 MHz
• Mode : USB
• Receiving
• Display frequency : 44.999999 MHz
• Mode : USB
• Receiving
• Display frequency : 60.000000 MHz
• Mode : USB
• Receiving
• Display frequency :
0.030000 MHz, 7.999999 MHz
8.000000 MHz, 19.999999 MHz
20.000000 MHz, 44.999999 MHz
45.000000 MHz, 60.000000 MHz
• Receiving
• Sub display freq. : 0.030000 MHz
• Mode : USB
• Receiving
• Sub display freq.
: 7.999999 MHz
• Mode : USB
• Receiving
• Sub display freq. : 19.999999 MHz
• Mode : USB
• Receiving
• Display frequency : 44.999999 MHz
• Mode : USB
• Receiving
• Display frequency : 60.000000 MHz
• Mode : USB
• Receiving
• Sub display freq. :
0.030000 MHz, 7.999999 MHz
8.000000 MHz, 19.999999 MHz
20.000000 MHz, 44.999999 MHz
45.000000 MHz, 60.000000 MHz
• Receiving
• Display frequency
: Any
• Receiving
• Display frequency : Any
• Receiving
PLL
PLL
PLL
PLL
PLL
PLL
PLL
PLL
PLL
Connect a frequency
counter to check
point P81.
Connect an RF volt-
meter to check point
P81.
Connect a digital
multimeter or oscillo-
scope to check point
LPA.
Connect a digital
multimeter or oscillo-
scope to check point
LVA.
Connect an RF volt-
meter to check point
P351.
Connect a digital
multimeter or oscillo-
scope to check point
LPB.
Connect a digital
multimeter or oscillo-
scope to check point
LVB.
Connect an RF volt-
meter to check point
P651.
Connect an RF volt-
meter to check point
P701.
Connect an RF volt-
meter to check point
P801.
64.000000 MHz
Maximum level
(0 dB or more)
2.0 V
4.3 V
4.3 V
4.3 V
4.3 V
0 dBm or more
2.0 V
4.3 V
4.3 V
4.3 V
4.3 V
0 dBm or more
–16 dBm or more
–7 dBm or more
PLL
PLL
PLL
PLL
PLL
L52
(R33
for critical
adjustment)
L81, L82
C154
C278
C258
C228
C208
Verify
C454
C578
C558
C528
C508
Verify
Verify
Verify