4
5. Squelch Circuit
The detected output which is outputted from the pin 12 of IC108 is inputted to
pin 19 of IC108 after it was been amplified by IC104:A and it is outputted from
pin 20 after the noise component was been eliminated from the composed
band pass filter in the built in amplifier of the IC, then the signal is rectified by
D106 to convert into DC component. The adjusted voltage level at VR101 is
delivered to the comparator of the CPU.
The voltage is led to pin 2 of CPU and compared with the setting voltage. The
squelch will open if the input voltage is lower than the setting voltage.
During open squelch, pin 30 (SQC) of the CPU becomes "L" level, AF control
signal is being controlled and sounds is outputted from the speaker.)
6. AIR Band Reception(T only)
When the frequency is within 118~135.995MHz, Q110 automatically turns ON,
pin 14 of IC108 becomes "L" level and the condition becomes in AM detection
mode.
The receiver signal passed through the duplexer is let to the antenna switch
(D107,D101). After passing through the band-pass filter, the signal is amplified
by RF amplifier Q112. Secondly the signal is mixed with the signal from the first
local oscillator in the first-mixer Q106,then converted into the first IF. Its unwanted
signal is let to IC106, pin24. Then converted into the second IF. and is demodulated
by AM decoder of IC106, and is output from pin13 as the AF signal.
7. WIDE/NARROW switching circuit
The 2nd IF 450 kHz signal which passes through filter FL101 (wide) and FL102
(narrow) during narrow, changes its width using the width control switching
IC103 and IC102.
2) Transmitter System (DR-135)
1. Modulator Circuit
The audio signal is converted to an electrical signal by the microphone, and
input it to the microphone amplifier (Q6). Amplified signal which passes through
mic-mute control IC109 is adjusted to an appropriate mic-volume by means of
mic-gain adjust VR106.
IC114:A and B consists of two operational amplifiers; one amplifier (pins 1, 2,
and 3) is composed of pre-emphasis and IDC circuits and the other (pins 5, 6,
and 7) is composed of a splatter filter. The maximum frequency deviation is
obtained by VR107. and input to the signal switch (IC113) (9600 bps packet
signal input switch) and input to the cathode of the varicap of the VCO, to
change the electric capacity in the oscillation circuit. This produces the frequency
modulation.
Содержание DR-135
Страница 14: ...14 12 M3826M8L269GP XA0818 CPU Terminal Connection TOP VIEW 269 ...
Страница 23: ...23 11 M57788M XA0077 ...
Страница 31: ...31 3 LCD Assembly FF0017 NUT UE0035 FM0034 FG0305 CPU BOARD ST0064 EL0049 TL0024 DG0037 TL0023 NUT ST0068 ...
Страница 59: ...59 3 MAIN Unit Side A DR 135 UP 0400B 4 MAIN Unit Side B DR 135 UP 0400B ...
Страница 61: ...61 7 MAIN Unit Side A DR 435 UP 0415 VCO Unit Side A VCO Unit Side B 8 MAIN Unit Side B DR 435 UP 0415 ...
Страница 62: ...62 9 TNC Unit Side A UP 0402 DR 135TP only OPTION unit EJ41U 10 TNC Unit Side B UP 0402 DR 135TP only ...
Страница 65: ...65 3 MAIN Unit DR 235 TO CN6 OPTION CN7 TO CPU CN2 TO CPU CN1 TO OPTION Downloaded by RadioAmateur EU ...
Страница 67: ...67 5 TNC Unit DR 135TP only or option CN6 CN7 TO MAIN CN107 ...
Страница 68: ...68 BLOCK DIAGRAM 1 DR 135 ...
Страница 69: ...69 2 DR 235 Downloaded by RadioAmateur EU ...
Страница 70: ...70 3 DR 435 ...