Vertex Standard EVX-5300, Руководство по обслуживанию

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EVX-5300/-5400 UHF Service Manual 11
Circuit Description
3. PLL Frequency Synthesizer
The frequency synthesizer consists of VCO, TCXO (X1002),
and the custom IC Q1070 (RFIC).
The output frequency from TCXO is 19.2 MHz and the toler-
ance is ±1.5 ppm in the temperature range –22 °F to +140 °F
(–30 °C to +60 °C).
3-1. vCo
(
v
oltage
C
ontrolled
o
sCillator
)
While the radio is receiving, the RX oscillator Q1055
(2SK508) generates a programmed frequency between 352.15
and 419.15 MHz (Type “G6”) or 399.15 and 469.15 MHz
(Type “G7”) as 1st local signal.
While the radio is transmitting, the TX oscillator Q1054
(2SK508) generates a frequency between 403-470 MHz (Type
“G6”) or 450-520 MHz (Type “G7”).
The output from oscillator is amplified by buffer amplifier
Q1064 (2SC5006) and then is divided, one is fed back to the
PLL Circuit in the custom IC Q1070 (RFIC). The other one
is supplied to the 1st mixer Q1053 (AK1220) in case of the
reception. In the transmission, the output is modulated to the
FM (or digital) in the custom IC Q1070 (RFIC), and then
supplied to the transmitter section described previously.
3-2. vCv
(
v
araCtor
C
ontrol
v
oltage
)
C
ontrol
The tuning voltage (VCV) of the VCO establishes the lock
range of VCO by controlling the cathode of varactor diode
(D1029 (1SV279), D1032 (Type “G6”: 1SV279, Type “G7”:
1SV280), D1036 (1SV279), and D1037 (Type “G6”: 1SV279,
Type “G7”: 1SV280) for receiving, and D1028 (1SV279),
D1031 (Type “G6”: 1SV279, Type “G7”: 1SV280), D1034
(1SV279), & D1035 (Type “G6”: 1SV279, Type “G7”:
1SV280) for transmitting) from the custom IC Q1070 (RFIC).
3-3. pll
The main constitution product of the PLL is equipped all with
in the custom IC Q1070 (RFIC), so that all processing re-
garding the frequency control is performed in the custom IC
Q1070 (RFIC).