Vertex Standard VX-2500U, Service Manual

Page: 12 / 79

12
While receiving, VCO Q1013 oscillates between 355.75 and
475.75 MHz according to the transceiver version and the
programmed receiving frequency. The VCO generates
355.75 to 475.75 MHz for providing to the first local sig-
nal. In TX, the VCO generates 400 to 520 MHz.
The output of the VCO is amplified by the Q1020 and
routed to the pin 5 (Ver. D) or pin 8 (Ver. CS1, DS1) of the
PLL IC. Also the output of the VCO is amplified by the
Q1021 and routed first local/Power Module according to
D1022 .
PLL data is output from "DCS_E" (pin100), "CLOCK"
(pin2) and "PLL_E" (pin98) of the microprocessor
Q2013 .
The data are input to PLL IC when the channel is changed
or when transmission is changed to reception and vice
versa. A PLL lock condition is always monitored by the
pin20 of the
Q2013 . When the PLL is unlocked, the UL
goes low.
6. Miscellaneous Circuits
6-1 DCS/LTR Demodulator
DCS signals are demodulated on the PANEL-UNIT, It is
demodulated by
Q2116 ( AK2345 ), amplifier Q2015 , and
comparator Q2021 .
6-2 CTCSS encoder/decoder
The CTCSS code is generation and encoding by CTCSS
encoder/decoder IC
Q2016 ( AK2345 ).
6-3 MPU
Operation is controlled by 8-bit MPU IC Q2013
( LC87F72C8A ). The system clock uses a 3.6864MHz crys-
tal for a time base. IC Q2003 ( S-80735SN ) resets the MPU
when the power is on, and monitors the voltage of the
regulated 5V power supply line.
6-4 DCS/LTR Encorder
The DCS code is generation and encoding by MPU IC
Q2013 ( LC87F72C8A ). It is filtered by Q2021 ( NJM2902V )
and adjusted the level by Q2014 ( M62364FP ).
6-5 Compandor
The Compandor is active when Pin90 of Q2013
( LC87F72C8A ) is “High”. When the Compandor is ac-
tive, MIC Audio is compressed, and detected audio is ex-
panded by
Q2017 ( LA8630M ).
7. Power Supply Circuits
7-1 All 13.8V
13.8V is always supplied to Power AMP Q1014
( RA30H4452M :Ver. D, DS1 or RA30H4047M :Ver. CS1).
Switched 13.8V is supplied to AF Power AMP Q1509
( TDA2003H ) and 9V Regulator Q1004 ( MM1216EN ) and
Q1005 (
2SB1201STP
).
7-2 All 9V
9V regulated from 13.8V by Q1004 ( MM1216EN ) and
Q1005 ( 2SB1201STP ).
7-3 VCO 9V
9V is filtered by Ripple Filter and is supplied to VCO Os-
cillator
Q1013 ( 2SK508-K52 ), Q1015 ( 2SC5107-O ), and
VCO BUFFER AMP Q1015 ( 2SC5107-O ).
7-4 5V (RF-UNIT)
5V in RF-UNIT is regulated by REGULATOR IC Q1024
( NJM78L05UA ). 5V is supplied to PLL IC Q1023
( SA7025DK :Ver. D) or Q1038 ( MB15A02PFV1 :Ver. CS1,
DS1), FM IC Q1028 ( TA31136FN ), and Reference Oscilla-
tor Q1027 ( 23C4116GR ).
7-5 TX 9V
TX 9V is active on transmit. TX 9V is supplied to ANT SW
D1005 , D1007 ( XB15A709A0HR ) and TX DRIVER Q1022
( 2SC5415E ), Q1025 ( 2SC5107-O ).
7-6 RX 9V
RX 9V is active on receive. RX 9V is supplied to RX RF
AMP
Q1011 ( 2SC4227 :Ver. D or 2SC4226 :Ver. CS1, DS1)
and MIXER Q1026 ( 3SK228 :Ver. D or SGM2016AM :Ver.
CS1, DS1).
7-7 5V (RF-UNIT)
9V from RF-UNIT is regulated to 5V by REGULATOR IC
Q2006 ( NJM78L05UA ) in PANEL-UNIT.
Circuit Description