Icom IC-RP1620 Service Manual page 28

6-2 RX PLL ADJUSTMENT
*
Example of setting N-data for receiving
Receive frequency : 136.000 MHz
1st IF frequency :
21.800 MHz (fixed)
PLL reference frequency : 0.005 MHz (5 kHz)
N-data for- receive frequency
-
1 st IF frequency
receiving
-
PLL reference frequency
VALUE
1.5V
(Low-band version)
4.0 V
(High-band version)
ADJUSTMENT
POINT
=
22840
1
Receive frequency : 150.000 MHz
1 st IF frequency : 21.800 MHz (fixed)
PLL reference frequency : 0.0125 MHz (12.5 kHz)
2
UNIT
RX
(R-VCO)
N-data f o r _ ~ i v e frequency
-
1 st IF frequency
receiving PLL reference frequency
After adjustment, program the identification frequency.
ADJUSTMENT CONDITIONS
Set the receive frequency
(See below) :
136.000 MHz (Low-band version)
150.000 MHz (High-band version)
Receiving
ADJUST
C1
MEASUREMENT
ADJUSTMENT
L0GIC.A UNlT
UNIT
RX
(R-VCO)
LOCK
VOLTAGE
Setting
N-data for
receiving
LOCATION
Connect the DC
voltmeter to R32.
(Ql
1
Collector side)
1
Set the dip switches (SI, S2) to the values
equivalent to the obtained N-data.
Example of setting the dip switches.
S1 S2
- N - ~ W ~ ~ ~ W S ~
Dip N-data
switches value
$2-5
+
16384
52-3
+
4096
52-2
+
2048
S1-9
+
256
S1-6
+
32
$1-5
+
16
$1-4
+
8 ( +
Total 22840
Dip N-data
switches value
52-4
+
8192
S2-2
+
2048
Sf-5 16(+
Totat 10256
RX UNlT
C1
Lock voltage
adjustment
R-VCO UNlT
R32
Lock voltage
check point