Vertex Standard VXR-9000EV, Руководство по обслуживанию

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TX PLL and VCO Circuits
The transmitter’s PLL circuitry consists of PLL subsystem
IC
Q1008 ( MB15A02PFV1 ) on the MAIN Unit, which con-
tains a reference oscillator/divider, serial-to-parallel data
latch, programmable divider, phase comparator and a
swallow counter. Stability is obtained by a regulated 5 V
DC supply via
Q1062 ( L78M05T ) and temperature com-
pensated 14.4 MHz crystal oscillator X1001 .
The TX VCO consisting of transistor Q1021 ( 2SC5107 )
and varactor diodes D1008 and D1009 (both HVU306 )
oscillates between 148 MHz and 174 MHz according to
the programmed transmit frequency. The theory of oper-
ation of the remainder of the PLL circuitry is similar to
that of the RX PLL circuit; however, dividing data from
the Main
Q3014 ( HD64F2238BFA13 ) on the CNTL Unit
is such that the VCO frequency is the actual transmit fre-
quency.
APC (Automatic Power Control)
RF power output from the final amplifier module Q7007
( S-AV33 ) is sampled by C7041 and C7044, then rectified
by D7006 and D7007 (both HSM88AS ). The resulting DC
voltage from the Main CPU
Q3014
( HD64F2238BFA13 )
on the CNTL Unit, to produce a control voltage for the
Automatic Power Controller
Q7018 ( LM2904PW ), which
regulates control voltage of Q7007 ( S-AV33 ).
Circuit Description
F-3
CNTL (Control) Unit
The CNTL Unit consists of 8-bit CPU Q3014
( HD64F2238BFA13 ), EEPROM Q3006 ( BR24L32F ), RX
and TX speech audio circuits, and various analog switch-
es for the CPU and repeater interconnections.
Microprocessor operational code is stored in Q3006
( BR24L32F ), while channel data and repeater configura-
tion information is programmed from an external PC con-
nected to the front panel’s MIC jack via a VPL-1 program-
ming cable.
T h e o u t p u t f r o m t h e M a i n C P U Q 3 0 1 4
( HD64F2238BFA13 ) contains serial control data used for
REPEATER/BASE mode control, as well as TX and RX PLL
data. Crystal
X3002 oscillates at 12.288 MHz, and provides
s t a b l e c l o c k t i m i n g f o r t h e M a i n C P U Q 3 0 1 4
( HD64F2238BFA13 ). When the repeater is powered on,
the voltage at pin 62 of Q3014 ( HD64F2238BFA13 ) be-
comes stable, and the output of voltage detector IC
Q3012
( BD4845FVE ), which is tied to pin 59 (RST) of Q3014
( HD64F2238BFA13 ) becomes high, resetting the Main
CPU.
Base Operation (TX, Mic-Input Audio)
Microphone input is delivered past the MIC MUTE switch
Q4002 ( DTC323TK ), then passes through the audio am-
plifier and active high pass filter at
Q4001
( NJM2902V )
when the signal is processed in the same manner as previ-
ously described.