Icom IC-725 Service Manual page 25

6·2 PLL ADJUSTMENT
MEASUREMENT
ADJUSTMENT
POINT
ADJUSTMENT
ADJUSTMENT CONDITIONS VALUE
UNIT LOCATION
UNIT ADJUST
REFERENCE 1 •Displayed frequency: 14.10000 MHz PLL Terminate P4 to Pre-set to center. PLL C134
FREQUENCY •Mode : USB ground with a
so n
-
•Receiving
•
resistor.
2 Connect the RF Maximum level (More
L38, L39
voltmeter to P4. than +3 dBm)
-
3 Connect the 61.4400 MHz L3S
frequency counter
to P4.
4 After adjustment, remove the resistor from P4 and re-plug P4.
DDS CLOCK 1 • Displayed frequency: 14.10000 MHz DDS Connect the S.24288 MHz DDS C1
•Mode : USB frequency counter
•Receiving to IC4 pin 11 or ICS
pin 11.
DDS LOOP 1 •Displayed frequency: 14.126SO MHz PLL Connect the 1.0 V DC PLL L30
•Mode :AM oscilloscope to R133
•Receiving (rear panel side).
2 •Displayed frequency: 14.12649 MHz Approx. 2.0 V DC Verify
1ST LO 1 •
Display~d
frequency:.7.99999 MHz PLL Connect the 6.S V DC
PLL C3S
LOCK •Mode : USB oscilloscope to R77.
VOLTAGE •Receiving
(shielding case side)
2 •Displayed frequency: 14.99999 MHz 6.S V DC
C46
3 •Displayed frequency: 21.99999 MHz 6.S V DC
CS9
4 •Displayed frequency: 33.00000 MHz 7.S V DC
C70
s
• Displayed frequencies: More than 2.0 V DC Verify
O.SOOOO MHz, 8.00000 MHz,
1S.OOOOO MHz and 22.00000 MHz
1ST LO
1 •Displayed frequency: 14.10000 MHz PLL Terminate PS to More than 0 dBm Verify
OUTPUT
•Mode : USB ground with a
so n
LEVEL •Receiving resistor.
Connect the RF
voltmeter to PS.
2 After adjustment, remove the resistor from PS and re-plug PS.
RIT 1 • Displayed frequency: 14.10000 MHz Top Speaker
Pre-set to center.
Front [RIT]
•Mode : USB cover panel control
• Set the signal generator;
-
Level
: SO µV (-73 dBm)
2
Modulation: OFF
Same tone pitch on
PLL
R70
• [RIT] switch :ON and OFF
both conditions.
•Receiving
6-2