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28
VX-450 Series UHF Band Service Manual
When the detection voltage is low, the CPU makes
Q3049
ON with making 90 pin “H” and the AF sig-
nal is output.
2-5-2. Carrier Squelch
The CPU (14 pin: A/D port) detect RSSI voltage out-
put from
Q3033
12 pin, and controls AF output.
The RSSI output voltage changes according to the
signal strength of carrier. The stronger signal makes
the RSSI voltage to be higher voltage.
The process of the AF signal control is same as Noise
Squelch.
The shipping data is adjusted –1dBu (EMF) higher
than squelch tight sensitivity.
3. Transmitter System
3-1. MIC Amplifier
The AF signal from internal microphone
MC2001
(Non key Type:
MC3001
) or external microphone
J3004
in to Audio processor IC
Q3013
(selected 33
pin or 34 pin).
Q3013
is which contains the micro-
phone amplifier, compandor, Pre-emphasis, limiter
and splatter filter, the processed signal to made FM
modulation to transmit carrier by the modulator
D3014
(
HVC383B
) of VCO.
Q3013
is built-in DTMF Receiver, and Inversion Type
Encryption.
3-2. Drive and Final Amplifier Stages
The modulated signal from the VCO
Q3023
(
2SC4227
) is buffered by
Q3017
(
2SC5005
). Then
the signal is buffered by
Q3010
(
2SC3356
) for the
final amplifier driver
Q3015
(
RQA0004PXDQS
). The
low-level transmit signal is then applied to
Q3006
(
RQA0011DNS
) for final amplification up to 5 watts
output power.
The transmit signal then passes through the antenna
switch
D3005
(
HVU131
) and is low pass filtered to
suppress away harmonic spurious radiation before
delivery to the antenna.
3-3. Automatic Transmit Power Control
The current detector
Q3040-1
(
NJM12904V
) detects
the current of
Q3006
and
Q3008
, and converts the
current difference to the voltage difference.
The output from the current detector
Q3040-1
is com-
pared with the reference voltage and amplified by
the power control amplifier
Q3040-2
.
The output from
Q3040-2
controls the gate bias of
the final amplifiers
Q3006
and the final amplifier
driver
Q3008
.
The reference voltage changes into four values
(Transmit Power High and Low) controlled by
Q3040
(
NJM12904V
).
4. PLL Frequency Synthesizer
The frequency synthesizer consists of PLL IC,
Q3036
(
AK1541
), VCO, TCXO (X3001).
The output frequency from TCXO is 16.8 MHz and
the tolerance is ±2.5 ppm (in the temperature range
–30 to +60 degrees).
4-1. VCO (Voltage-Controlled Oscillator)
While the radio is receiving, the RX oscillator
Q3019
(
2SK508
) in VCO generates a programmed fre-
quency between 282.35 and 322.35 MHz (Version “I”)
or 249.15 and 289.15 MHz (Version “K”) as 1st local
signal.
While the radio is transmitting, the TX oscillator
Q3023
(
2SC4227
) in VCO generates a frequency be-
tween 350 and 390 MHz (Version “I”) or 300 and 340
MHz (Version “K”).
The output from oscillator is amplified by buffer
amplifier
Q3017
(
2SC5005
) and becomes output of
VCO. The output from VCO is divided, one is am-
plified by
Q3022
and feed back to the PLL IC 17 pin.
The other is amplified in
Q3014
and in case of the
reception, it is put into the mixer as the 1st local sig-
nal through
D3011
, in transmission, it is buffered
Q3010
, and more amplified in
Q3008
and it is put
into the final amplifier
Q3006
.
4-2. VCV (Varactor Control Voltage) Control
Tuning voltage of VCO is expanding the lock range
of VCO by controlling the cathode of varactor diode
at the voltage and the control voltage from PLL IC.
Circuit Description (Version I & K)
Содержание VX-450 series
Страница 8: ...8 VX 450 Series UHF Band Service Manual Block Diagram Version A D 16 key 4 key Type RF Section ...
Страница 10: ...10 VX 450 Series UHF Band Service Manual Block Diagram Version A D 16 key 4 key Type AF Section ...
Страница 11: ...11 VX 450 Series UHF Band Service Manual Block Diagram Version A D 16 key 4 key Type Controller Section ...
Страница 12: ...12 VX 450 Series UHF Band Service Manual Block Diagram Version A D Non key Type RF Section ...
Страница 14: ...14 VX 450 Series UHF Band Service Manual Block Diagram Version A D Non key Type AF Section ...
Страница 15: ...15 VX 450 Series UHF Band Service Manual Block Diagram Version A D Non key Type Controller Section ...
Страница 16: ...16 VX 450 Series UHF Band Service Manual Block Diagram Version I K 16 key 4 key Type RF Section ...
Страница 18: ...18 VX 450 Series UHF Band Service Manual Block Diagram Version I K 16 key 4 key Type AF Section ...
Страница 19: ...19 VX 450 Series UHF Band Service Manual Block Diagram Version I K 16 key 4 key Type Controller Section ...
Страница 20: ...20 VX 450 Series UHF Band Service Manual Block Diagram Version I K Non key Type RF Section ...
Страница 22: ...22 VX 450 Series UHF Band Service Manual Block Diagram Version I K Non key Type AF Section ...
Страница 23: ...23 VX 450 Series UHF Band Service Manual Block Diagram Version I K Non key Type Controller Section ...
Страница 44: ...44 VX 450 Series UHF Band Service Manual MAIN Unit Circuit Diagram Version A D 16 key 4 key Type Lot 1 4 ...
Страница 47: ...47 VX 450 Series UHF Band Service Manual MAIN Unit Circuit Diagram Version A D 16 key 4 key Type Lot 5 6 ...
Страница 50: ...50 VX 450 Series UHF Band Service Manual MAIN Unit Circuit Diagram Version A D 16 key 4 key Type Lot 7 ...
Страница 53: ...53 VX 450 Series UHF Band Service Manual MAIN Unit Circuit Diagram Version A D Non key Type Lot 1 7 ...
Страница 56: ...56 VX 450 Series UHF Band Service Manual MAIN Unit Circuit Diagram Version A D Non key Type Lot 8 ...
Страница 59: ...59 VX 450 Series UHF Band I Band Service Manual MAIN 2 Unit Circuit Diagram Version I K 16 key 4 key Type ...
Страница 62: ...62 VX 450 Series UHF Band I Band Service Manual MAIN 2 Unit Circuit Diagram Version I K Non key Type ...
Страница 65: ...65 VX 450 Series UHF Band Service Manual DISPLAY Unit Circuit Diagram 16 key 4 key Type Lot 1 4 ...
Страница 68: ...68 VX 450 Series UHF Band Service Manual DISPLAY Unit Circuit Diagram 16 key 4 key Type Lot 5 Circuit Diagram ...