Precaution; Specific Service Instructions - Kenwood TH-D74E Service Manual

This service manual does not describe PRECAUTION.
2.1 Circuit Description
2.1.1 Outline
The TH-D74E is an FM dual-band transceiver designed for amateur radio applications in the 144/430 MHz bands.
2.1.2 Frequency Configuration
This transceiver has two discrete VCO/PLL and IF circuit configurations for the A-band and B-band to achieve simultaneous dual-band
signal reception and full-duplex operation.
The VCO block of the A-band is used as the first local oscillator for VHF and UHF reception in the A-band. The VCO block for the
B-band is composed of two VCOs including modulation circuitry and used as the first local oscillator for the VHF/UHF transmission of
signals and reception of signals in a range of 0.1 to 524 MHz in the B-band.
The 19.200 MHz reference oscillator connected to the PLL IC for the A-band is used to generate a PLL comparison frequency.
The reference oscillator that generates a frequency of 57.600 MHz tripled from the 19.200 MHz is used for the comparison frequency
of the PLL IC for the B-band. Furthermore, this reference oscillator is used as the second local oscillator for the reception of signals
in both A-band and B-band.
MIC AMP
AF AMP
Table 1 Frequency configuration
TH-D74E (E-type)
A 144.000 ~ 145.995MHz
430.000 ~ 439.995MHz
B 0.100 ~ 75.995MHz
108.000 ~ 523.995MHz
C 136.000 ~ 173.995MHz
410.000 ~ 469.995MHz
D 58.150 ~ 468.045MHz
E 193.150 ~ 412.845MHz
SECTION 1

PRECAUTION

SECTION 2

SPECIFIC SERVICE INSTRUCTIONS

MAIN MPU
(DSP)
19.20M 57.60M
x3
MAIN MPU
BAND A PLL
(DSP)
Fig.1 Frequency configuration
A
1/2,1/4,1/8
BAND B PLL
D B
BAND B
BAND B RX
DEMODULATOR
58.05M
450.0k 460.8k
FM RADIO
x2
E C
BAND A
DEMODULATOR BAND A RX
57.15M
ANT
TX
BAR ANT
(No.RA044<Rev.001>)1-5