Kenwood TM-V7A Service Manual

TM-V7A/E
10
CIRCUIT DESCRIPTION
Tone Output Circuit
The tone signals (38 waves within 67.0 to 250.3Hz) are
output from ANOO of the microprocessor (1C408) analog
output board.
DTMF Encode/Decode Circuit
@DTMF encode circuit
The DTMF signals are output from ANO1 of the
microprocessor (IC508) analog output board.
ANOO
ANO1
CPU
P55
P54
P56
@DTMF decode signals
The reception signals, the DTMF signals from a mic with
DTMF (M2, E, E3: optional), go into the DTMF decoder IC
(IC506: LC73881M). When a valid tone pair is detected,
STD of the DTMF decoder IC (IC506) goes high. This is
input to the P56 port of the microprocessor (IC508), the
serial clock is output from P54 of the microprocessor
(IC508) to the DTMF decoder IC (IC506), and the serial
data is sent to the P55 port of the microprocessor.
we Tone output
we DTMF output
IC506 1C510
SD —_— MIC
DTMF
pe ACK jt -<a——_— RDV
STD —t-—-——— RDU
DTMF Cross point
decoder switch
Fig.9 DTMF encode/decode circuit
Analog Signal Switching Circuit
Cross point switches (IC503 and IC510: JLC1555F) are
used for AF system signal switching and RD system signal
switching. These cross point switches use serial data from
the microprocessor to switch analog switches arrayed in a
matrix.
Audio signa! switching is carried out by a cross point
switch (IC503). The destination for input from MIC RD,
DTMF RD, and CTCSS RD is switched to either the 144-
MHz band or the 430-MHz band by a cross point switch
(IC510).
@AF system signal switching
(IC503SW No. 16, 17, 20, and 21)
These switches (shown in Tables 5 and 6) output the
144MHz AF signals and 430MHz AF signais from the
electrode control to either AOO or AO1.
When SW No16 is ON, AOO- 430MHz AF external SP output
When SW No21 is ON, AO1- 144MHz _ AF internal SP output
When SW No20 is ON, AOO- 144MHz AFexternal SP output
When SW No17 is ON, AO1- 430MHz_AF internal SP output
Tables
@Beep output switching (IC503SW No. 6 and 7)
These switches output the Beep signal from the
microprocessor (IC508) to either RIN or LIN of the
electronic control (1C504: MB87032APFGBND) and to the
corresponding band 144 MHz or 430 MHz. (See Tables 6
and 7.)
@DTMF output switching (IC503SW No. 2 and 3)
These switches output the DTMF signals from the
microprocessor (IC508) to either RIN or LIN of the
electronic control (IC504) and to the corresponding band
144 MHz or 430 MHz. (See Table 6.)

Kenwood TM-V7A Specifications

General Specifications

VHF frequency range	144~148MHz
UHF frequency range	438~450MHz (U.S.A/Canada)
Antenna impedance	50Ω
Usable temperature range	-20°C to +60°C (-4°F to +140°F)
Power supply	13.8V DC ±15% (11.7~15.8V)
Grounding method	Negative-ground
Frequency stability	±3ppm (-10°C to +50°C)
Dimensions (W x H x D)	140 x 54.5 x 205.5 mm

Transmitter Specifications

High power output	50W (VHF) / 35W (UHF)
Mid power output	Approx. 10W
Low power output	Approx. 5W
Spurious emissions	-60dB or less
Maximum frequency deviation	±5kHz
Audio distortion	3% or less (at 60% modulation)
Microphone impedance	600Ω

Receiver Specifications

Circuitry	Double conversion
Intermediate frequency (1st / 2nd)	38.85MHz / 450kHz and 45.05MHz / 455kHz
Sensitivity (VHF or UHF band)	0.16μV or less (12dB SINAD)
Sensitivity (Sub VHF or UHF band)	0.25μV or less
Selectivity (-6dB)	12kHz or more
Selectivity (-60dB)	28kHz or less
Squelch sensitivity	0.1μV or less
Audio output	2W or higher (8 ohms, 5% distortion)
Audio output impedance	8Ω

Weight and Dimensions

Weight	1.2 kg (2.6 lb)
Dimensions (W x H x D)	5.51" x 2.15" x 8.09"