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Part 3.3: The UHF VCO and Synthesiser
The UHF VCO and Synthesiser can be checked with the receiver set to the same
setting as previously described. Obviously being a dual band product DB2000
has two UHF VCO's, so therefore both VCO's need to be checked. Please refer to
figure 3.2: UHF VCO's and Synthesiser, for signal levels and control voltages.
8
13MHz
DIV
200Khz
CLK
65
PHASE
DIFFERENCE
(CURRENT)
RX Channel
1
62
512
698
Figure 3.2: UHF VCO's and Synthesiser
IC201 LMX2331L RF-PLL
PHASE
COMPARATOR
200Khz
SCALER
3
LOOP
FILTER
GND
VCO Input Voltage Output Level in dbm's
2.5 V.d.c
2.8 V.d.c
1.8 V.d.c
2.5 V.d.c
EG:1205Mhz (GSM)
PRE-
V_VC01/2
PHASE
NC
DIFFERENCE
(VOLTAGE)
3
IN
UHF VCO
I/P
5
GND
See table below for voltages
-21dbm
-21dbm
-11dbm
-11dbm
11,12,13
5
+ 5 V.d.c
1
4
2
O/P
OUT
See table below for levels
(IC202/3)
VCO Frequency
1205 Mhz
1217.4 Mhz
1535 Mhz
1572.4 Mhz
SERLT
SERDA
SERCK
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