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The VX-6R/E consists of a RF-UNIT, a CNTL-UNIT and
an AF-UNIT. The RF-UNIT contains the receiver front end,
PLL IC, power and switching circuits, and the VCO-UNIT
for transmit and receive local signal oscillation. The CNTL-
UNIT contains the CPU, and audio ICs, and the power
circuitry for the LCD. The AF-UNIT contains the IF, and
audio ICs.
Receiver Signal Flow
The VX-6R/E includes four receiver front ends, each
optimized for a particular frequency range and mode com-
bination.
(1) Triplexer
Signals between 0.5 and 580 MHz received at the an-
tenna terminal pass through a first low-pass filter.
Received 430 MHz band signals, after passing through
a low-pass filter to the UHF T/R switch circuit composed
of diode switch D1046, D1047.
Received 145 MHz band signals, after passing through
a low-pass filter to the VHF T/R switch circuit composed
of diode switch D1049, D1050.
Received 50 MHz band signals, after passing through
a low-pass filter to the 50MHz T/R switch circuit com-
posed of diode switch D1051, D1052.
(2) 0.50-60 MHz Reception
Received signals between 0.5 and 60 MHz pass through
the Triplexer circuit, low-pass filter circuit, T/R switch
diode D1051 and D1052 before additional filtering by a
band-pass filter prior to application to RF amplifier Q1008
(2SC5555ZD-TR). The amplified RF signal is pass through
the band-pass filter to first mixer Q1009 (2SC5555ZD-TR).
Meanwhile, 50MHz output from the VCO-UNIT is am-
plified by Q1019 (2SC5374-TL) and applied through di-
ode switch D1034 (DAN222M-T2L) to mixer Q1009
(2SC5555ZD-TR) as the first local signal. The 47.25 MHz
(Narrow, 45.8 MHz: Wide) intermediate frequency prod-
uct of the mixer is delivered to the AF-UNIT. The TUNE
voltage from the CPU on the CNTL-UNIT is amplified by
DC amplifier Q3017 (NJU7007F2-TE1) and applied to
varactor D1014 in the variable frequency band-pass fil-
ters. By changing the electrostatic capacitance of the var-
actors, optimum filter characteristics are provided for each
specific operating frequency.
Circuit Description
(3) 60-300MHz Reception
Received signals between 60 and 300 MHz pass
through the Triplexer circuit, low-pass filter/high-pass
filter circuit, VHF T/R switch circuit and protector diode
D1002 (1SS362-TE85R) before additional filtering by a
band-pass filter prior to application to RF amplifier Q1002
(2SC5555ZD-TR). The amplified RF signal is pass through
the band-pass filter to first mixer Q1007 (2SC5555ZD-TR).
Meanwhile, VHF output from the VCO-UNIT is ampli-
fied by Q1018 (2SC5374-TL) and applied through diode
T/R switch D1033 (DAN222M-T2L) to mixer Q1007
(2SC5555ZD-TR) as the first local signal. The 47.25 MHz
(Narrow, 45.8 MHz: Wide) intermediate frequency prod-
uct of the mixer is delivered to the AF-UNIT. The TUNE
voltage from the CPU on the CNTL-UNIT is amplified by
DC amplifier Q3017 (NJU7007F2-TE1) and applied to
varactors D1008 and D1009, D1011, D1012, D1020, D1021,
D1022, D1023, D1025 and D1026 in the variable frequen-
cy band-pass filters. By changing the electrostatic capaci-
tance of the varactors, optimum filter characteristics are
provided for each specific operating frequency.
(4) 300-580MHz Reception
Received signals between 300 and 580 MHz pass
through the Triplexer circuit, low-pass filter/high-pass
filter circuit, UHF T/R switch circuit and protector diode
D1001 before additional filtering by a band-pass filter prior
to application to RF amplifier Q1001 (2SC5555ZD-TR).
The amplified RF signal is pass through the band-pass
filter, RF amplifier Q1004 (2SC5555ZD-TR) and band-
pass filter to first mixer Q1006 (2SC5555ZD-TR). Mean-
while, UHF output from the VCO-UNIT is amplified by
Q1017 (2SC5374-TL) and applied through diode T/R
switch D1035 (HN2D01FUTE85R) to mixer Q1006 as the
first local signal. The 47.25 MHz (Narrow, 45.8 MHz:
Wide) intermediate frequency product of the mixer is
delivered to the AF-UNIT. The TUNE voltage from the
CPU on the CNTL-UNIT is amplified by DC amplifier
Q3017 (NJU7007F2-TE1) and applied to varactors D1006,
D1007, D1018 and D1019 in the variable frequency band-
pass filters. By changing the electrostatic capacitance of
the varactors, optimum filter characteristics are provided
for each specific operating frequency.
(5) 580 - 999 MHz Reception
Received signals between 580 and 999 MHz pass
through the high-pass filter circuit, switch D1003 to ap-
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