7
Circuit Description
The VX-7R 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-7R includes five receiver front ends, each op-
timized for a particular frequency range and mode com-
bination.
(1) Triplexer
Signals between 0.5 and 540 MHz received at the an-
tenna terminal pass through a first low-pass filter com-
posed of C1266, C1269, C1289, C1291, C1296, C1297,
L1059, L1060, L1067 and L1068.
Received 430-MHz signals, after passing through the
low-pass filter, are fed to the UHF T/R switch circuit com-
posed of diode switch D1048 (
RLS135
), D1051 (
1SV307
).
Received 145-MHz signals, after passing through the
low-pass filter, are fed to the VHF T/R switch circuit com-
posed of diode switch D1053 (
RLS135
), D1054 (
1SV307
).
Received 50-MHz signals, after passing through the low-
pass filter, are fed to the 50MHz T/R switch circuit com-
posed of diode switch D1058 (
RLS135
), D1059 (
1SV307
).
(2) 145-MHz Band and 76-300MHz Reception
Received signals between 76 and 300 MHz pass through
the Triplexer circuit, low-pass filter/high-pass filter cir-
cuit, VHF T/R switch circuit and protector diode D1002
(
1SS362
) before additional filtering by a band-pass filter
prior to application to RF amplifier Q1004 (
2SC5555
). The
amplified RF signal is passed through a band-pass filter
to first mixer Q1012 (
2SC5555
). Meanwhile, VHF output
from the VCO-UNIT is amplified by Q1017 (
2SC5374
)
and applied through diode T/R switch D1041 (
DAN222
)
to mixer Q1012 as the first local signal.
The 47.25-MHz 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
) and ap-
plied to varactors D1020 and D1022 (
HVC369B
), D1019,
D1021, D1023, D1024, D1033 and D1036 (
1SV325
) in the
variable frequency band-pass filters. By changing the elec-
trostatic capacitance of the varactors, optimum filter char-
acteristics are provided for each specific operating fre-
quency.
(3) 435-MHz Band and 222-540MHz Reception
Received signals between 222 and 540 MHz pass
through the Triplexer circuit, low-pass filter/high-pass
filter circuit, UHF T/R switch circuit and protector diode
D1001 (
1SS362
) before additional filtering by a band-pass
filter prior to application to RF amplifier Q1003
(
2SC5555
). The amplified RF signal is passed through a
band-pass filter, RF amplifier Q1006 (
2SC5555
) and band-
pass filter to first mixer Q1011 (
2SC5555
). Meanwhile,
UHF output from the VCO-UNIT is amplified by Q1016
(
2SC5374
) and applied through diode T/R switch D1045
(
HN2D01FU
) to mixer Q1011 as the first local signal.
The 47.25-MHz 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 and applied to varac-
tors D1005, D1018, D1030 and D1031 (
HVC358B
) in the
variable frequency band-pass filters. By changing the elec-
trostatic capacitance of the varactors, optimum filter char-
acteristics are provided for each specific operating fre-
quency.
(4) 50-MHz-Band and 30-76 MHz Reception
Received signals between 30 and 76 MHz pass through
the Triplexer circuit, low-pass filter circuit, 50 MHz T/R
switch circuit and protector diode D1003 (
1SS362
) be-
fore additional filtering by a band-pass filter prior to ap-
plication to RF amplifier Q1005 (
2SC5555
). The ampli-
fied RF signal is passed through a band-pass filter to first
mixer Q1008 (
2SC5555
). Meanwhile, 50 MHz output from
the VCO-UNIT is amplified by Q1018 (
2SC5374
) and
applied through diode T/R switch D1046 (
HN2D01FU
) to
mixer Q1008 as the first local signal.
The 47.25-MHz 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 and applied to varac-
tors D1025 and D1026 (
1SV325
) 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.
(5) 0.5 - 30 MHz Reception
Received signals between 0.5 and 30 MHz pass through
the Triplexer circuit, low-pass filter circuit, HF T/R switch
circuit and protector diode D1003 before additional fil-
tering by a band-pass filter prior to application to RF
amplifier Q1009 (
2SC4915-0
). The amplified RF signal is
Summary of Contents for VX-7R
Page 5: ...5 Block Diagram ...
Page 6: ...6 Interconnection Diagram ...
Page 21: ...21 RF Unit Lot 4 Circuit Diagram ...
Page 35: ...35 AF Unit Lot 3 Circuit Diagram ...
Page 37: ...37 AF Unit Lot 4 Circuit Diagram ...
Page 47: ...47 CNTL Unit Lot 3 Circuit Diagram ...
Page 49: ...49 CNTL Unit Lot 4 Circuit Diagram ...
Page 58: ...58 CNTL Unit Note ...
Page 63: ...63 Note ...
