Vertex Standard EVX-531 Service Manual page 10

3. PLL Frequency Synthesizer
The frequency synthesizer consists of VCO, TCXO (Xx501),
and the custom IC Qx522 (RODINIA).
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
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oltage ontrolled
While the radio is receiving, the RX oscillator Qx506
(2SC5006) 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 Q1505
(2SC5006) generates a frequency between 403-470 MHz
(Type "G6") or 450-520 MHz (Type "G7").
The output from oscillator is amplified by buffer amplifier
Qx516 (2SC5006) and then is divided, one is fed back to the
PLL Circuit in the custom IC Qx522 (RODINIA). The other
one is supplied to the 1st mixer Qx523 (3SK293) through the
buffer amplifier Qx524 (2SC5005) in case of the reception. In
the transmission, the output is modulated to the FM (or digi-
tal) in the custom IC Qx522 (RODINIA), and then supplied
to the transmitter section described previously.
EVX-531 UHF Service Manual
3-2. vCv ( v
The tuning voltage (VCV) of the VCO establishes the lock
range of VCO by controlling the cathode of varactor diode
(Dx502 (1SV279), Dx504 (Type "G6": 1SV282, Type "G7":
1SV279), Dx507 (1SV279), and Dx508 (Type "G6": 1SV282,
Type "G7": 1SV279) for receiving, and Dx501 (1SV279),
Dx503 (Type "G6": 1SV282, Type "G7": 1SV279), Dx505
) (1SV279), and Dx506 (Type "G6": 1SV282, Type "G7":
o
sCillator
1SV279) for transmitting) from the custom IC Qx522 (RO-
DINIA).
3-3. pll
The main constitution product of the PLL is equipped all with
in the custom IC Qx522 (RODINIA), so that all processing
regarding the frequency control is performed in the custom IC
Qx522 (RODINIA).
Circuit Description
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araCtor ontrol
Parts reference number is as follows
MAIN Unit (Type "G7", w/o Option Connector): 1000 - 1999
MAIN-2 Unit (Type "G6", w/o Option Connector): 2000 - 2999
MAIN-3 Unit (Type "G6" & "G7", w/ Option Connector): 3000 - 3999
) C
v
oltage ontrol
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