HYT TC-265 Service Manual page 18

2) CTCSS/CDCSS encoder
A necessary signal for CTCSS/CDCSS encoding is generated by MCU and FM-modulated to the PLL
IC reference signal. Since the reference OSC does not modulate the loop characteristic frequency or
higher, modulation is performed at the VCO side by adjusting the balance. (See Fig. 6)
3) 2-Tone/5-Tone encoder
The necessary signal for 2-Tone/5-Tone encoding is generated by MCU. The signal is sent to
IC500(TC-265）/IC1（TC-365）(2/2), and then applied to 3KHz low-pass filter. The resulting signal is
applied to VCO for direct modulation (See fig. 6).
MIC AMP
MIC
MUTE SW
4-a) RF amplifier (TC-265)
The RF signal obtained from the VCO buffer amplifier Q100 is amplified by Q101 and Q102. This
amplified signal is passed to the power amplifier, Q102 and Q105, which consists of a 2-stage FET
amplifier and is capable of producing up to 4.5W of RF power (See Fig. 7-a).
1
D
AMP
C
5T
B SW
B
B
APC
A
1
4-b) RF amplifier (TC-365)
The RF signal obtained from the VCO buffer amplifier Q136 is amplified by Q135 and Q134. This
amplified signal is passed to the power amplifier, Q131 and Q129, which consists of a 2-stage FET
amplifier and is capable of producing up to 4W of RF power (See Fig. 7-b)
PRE EMPHASIS
IDC
2 TN/5 TN
Decoder
Fig. 6. Transmit audio CTCSS/CDCSS
2
DRIVE AMP FINAL AMP
APC
SW
5T
SW
5T
2
Fig. 7-a. APC system
TC-265/365 SERVICE MANUAL
LPF MAX DEV
MCU TO
MUTE
3
ANT SW
SW
Title
Size Number
B
Date: 22-Nov-2003
File: D:\TC366 CE\service manual\service\ 周工 031120\ 维修手 册插图 .DDB
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VCO
Balance
(TCXO)
REFERENCE
OSC
4
ANT
D
LPF
C
B
A
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