Vertex Standard VX-7R Bedienungsanleitung PDF herunterladen (Seite 9)

Circuit Description

(2) Modulation

Voice signal input from either built-in microphone

MC3001 (EM-140) on the CNTL-UNIT or external jack

J2002 on the AF-UNIT is pre-emphasized by C3012 and

R3031, and processed by microphone amplifier Q3018

(NJM3403AV), IDC (instantaneous deviation control) cir-

cuit Q1014 to prevent overmodulation, and fed through

active low-pass filter Q1014.

During CTCSS operation, the voice signal is mixed with

the TONE ENC subaudible tone signal from pin 43 of the

CPU and delivered to the RF-UNIT through jacks J3003

and J1008. During DTMF operation, the DTMF tones from

pin 44 of the CPU are fed to the IDC stage.

(3) 145-MHz-Band Transmission

Modulating audio from the CNTL-UNIT passes through

deviation setting D/A converter Q3012 to the VHF modu-

lator portion of the VCO-UNIT mounted on the RF-UNIT.

This signal is applied to varactor D4005 (HSC277) in the

tank circuit of VHF VCO Q4004 (EC3H07B), which oscil-

lates at the desired VHF transmitting frequency. The

modulated VCO signal is buffered by amplifier Q4006

(EC3H07B) and Q1017 and delivered through VHF T/R

diode switch D1041 to the RF-UNIT. The modulated low-

level VHF transmit signal from the VCO is passed through

diode switch D1043 (DAN222) to amplifier Q1014

(2SC5226-5). The modulated VHF transmit signal from

the VCO is amplified by Q1023 (2SK3475) and RF power

amplifier Q1027 (2SK3476) up to 0.05, 1.0, 2.5 or 5 Watts

(depending on the power source). The RF output passes

through TX diode switch D1053. RF output is passed by

the T/R switch and low-pass filter to suppress harmonics

and spurious products before output gets to the antenna

at the antenna terminal.

(4) 435-MHz-Band Transmission

Modulating audio from the CNTL-UNIT passes through

deviation setting D/A converter Q3012 to the UHF mod-

ulator portion of the VCO-UNIT mounted on the RF-

UNIT. This signal is applied to varactor D4002 (HSC277)

in the tank circuit of UHF VCO Q4002 (EC3H07B), which

oscillates at the desired UHF transmitting frequency. The

modulated VCO signal is buffered by amplifier Q4006 and

Q1016 and delivered through UHF T/R diode switch

D1045 to the RF-UNIT. The modulated low-level UHF

transmit signal from the VCO is passed through diode

switch D1045 (HN2D01FU) to amplifier Q1014. The mod-

ulated UHF transmit signal from the VCO is amplified

by Q1023 and RF power amplifier Q1027 up to 0.05, 1.0,

2.5 or 5 Watts (depending on the power source). The RF

output passes through TX diode switch D1048. RF out-

put is passed through the T/R switch and low-pass filter

to suppress harmonics and spurious products before out-

put gets to the antenna at the antenna terminal.

(5) 50-MHz-Band Transmission

Modulating audio from the CNTL-UNIT passes through

deviation setting D/A converter Q3012 to the 50 MHz

modulator portion of the VCO-UNIT mounted on the RF-

UNIT. This signal is applied to varactor D4009 (HSC277)

in the tank circuit of 50 MHz VCO Q4005 (EC3H07B),

which oscillates at the desired 50 MHz transmitting fre-

quency. The modulated VCO signal is buffered by ampli-

fier Q4006 and Q1018 and delivered through 50 MHz T/R

diode switch D1046 to the RF-UNIT. The modulated low-

level 50 MHz transmit signal from the VCO is passed

through diode switch D1046 (HN2D01FU) to amplifier

Q1014. The modulated 50 MHz transmit signal from the

VCO is amplified by Q1023 and RF power amplifier Q1027

up to 0.05, 1.0, 2.5 or 5 Watts (depending on the power

source). The RF output passes through TX diode switch

D1058. RF output is passed through the T/R switch and

low-pass filter to suppress harmonics and spurious prod-

ucts before output gets to the antenna at the antenna ter-

minal.

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