Vertex Standard EVX-5300, Руководство по обслуживанию

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EVX-5300/-5400 UHF Service Manual 10
1. Receiver System
1-1. F
ront
-
end
rF
ampliFier
Incoming RF signal from the antenna passes through the
Low-pass ilter, antenna switching diode D1014, D1016 (both
JDP2S12CR), and the 1st RF attenuator Q1037 (SKY12338),
and then removed undesired frequencies by the varactor tuned
band-pass ilter D1022 and D1023 (both 1SV323).
The filtered RF signal is amplified by Q1045 (2SC3356)
and then passes through the varactor tuned band-pass filter
D1026, D1027, D1061 (all 1SV323) and the 2nd RF attenu-
ator Q1050 (SKY12338), and then applied to the 1st mixer
Q1053 (AK1220).
1-2. F
irst
m
ixer
The RF signal is mixed with the 1st local signal between
352.15 and 419.15 MHz (Type “G6”) or 399.15 and 469.15
MHz (Type “G7”) in the 1st mixer Q1053 (AK1220), to pro-
duce 50.85 MHz 1st IF signal.
The 1st local signal is generated by the VCO, which consists
of Q1055 (2SK508), varactor diodes D1029 (1SV279), D1032
(Type “G6”: 1SV279, Type “G7”: 1SV280), D1036 (1SV279),
and D1037 (Type “G6”: 1SV279, Type “G7”: 1SV280). The
1st local signal is supplied to the 1st mixer Q1053 (AK1220)
through the buffer amplifier Q1064 (2SC5006) and Q1066
(2SC5226).
1-3. iF a
mpliFier
& d
emodulator
The 1st IF signal is applied to the monolithic crystal filter
XF1001 to strip away all but the desired signal, and then sup-
plied to the custom IC Q1070 (RFIC) through the IF ampliier
Q1068 (2SC5226). The custom IC Q1070 (RFIC) converts
the 1st IF signal into the Base Band signal.
The Base Band signal from the custom IC Q1070 (RFIC) is
applied to another custom IC Q1001 (OMAP), which is de-
modulated by the Digital Signal Processor.
1-4. a
udio
a
mpliFier
The demodulated signal from the custom IC Q1001 (OMAP)
is applied to another custom IC Q1044 (PMAIC), which
convert to analog signal. The output signal from the custom
IC Q1044 (PMAIC) is applied to the AF amplifier Q1015
(NJM12902) and Q1027 (TDA1519CTH). The output signal
from Q1027 (TDA1519CTH) is applied to the front panel
audio speaker or external speaker which is connected to the
EXT SP jack (J1004).
2. Transmitter System
2-1. miC a
mpliFier
& m
odulator
The speech signal from the external microphone which con-
nected to the J2001 (EVX-5300) or J3001 (EVX-5400) is
supplied to the AF ampliier Q2005 (NJM2125: EVX-5300)
or Q3010 (NJM2125: EVX-5400), and then applied to the
custom IC Q1044 (PMAIC), which is amplified the speech
signal.
The amplified speech signal from the custom IC Q1044
(PMAIC) is supplied to another custom IC Q1001 (OMAP),
which process the speech signal by the Digital Signal Proces-
sor.
The processed speech signal from the custom IC Q1001
(OMAP) is supplied to the modulator section of the custom
IC Q1070 (RFIC), which modulates the speech signal into the
FM or digital signal.
2-2. d
rive
& F
inal
a
mpliFier
s
tages
The modulated signal from the custom IC Q1070 (RFIC)
is buffered by Q1061 (2SK3077) and amplified by Q1052
(RD01MUS1), and then is applied to the Power Module
Q1046 (RA60H3847M1A: Type “G6”, RA60H4452M1A:
Type “G7”), which is ampliied up to 45 watts output power.
The transmit signal then passes through the antenna switch
D1018 and D1019 (both MA4P959) and is low pass iltered
to suppress away harmonic spurious radiation before delivery
to the antenna.
2-3. a
utomatiC
t
ransmit
p
ower
C
ontrol
The forward power of the Power Module Q1046
(RA60H3847M1A: Type “G6”, RA60H4452M1A: Type
“G7”) is detected by D1020 (HSM88AS), and then applied to
the comparator Q1074 (ADM8566ARM).
The comparator Q1074 (ADM8566ARM) compares detected
voltage of forward power and power control voltage from
custom IC Q1070 (RFIC), makes output power stable by con-
trolling the bias voltage RF ampliier Q1052 (RD01MUS1).
Additionally, output voltage of operational amp Q1043 (AD-
M8566ARM) is supplied to Power Module. The output level
is controlled by Q1070 (RFIC) to three level (45 watt model)
or two level (25 watt model).
The Relection power from the antenna is detected by D1021
(HSM88AS), Automatic transmission power control circuit
protect equipment. For example, when the antenna is not con-
nected.
Circuit Description