4) DTMF Encoder Circuit (option)
The DTMF signal corresponding to the combination of the column and row is
output from tone output pin17 of IC401 Encoder, producing a frequency-
modulated RF output. The Q401 switches the DTMF Encoder when lC401 is
active during DTMF transmission.
5) Tone Squelch Circuit (option)
1.Decoder
The second IF signalfrom pin11 of IC1, and input to the tone squelch
decoder lC701.
When the tone squelch decoder IC701 decodes the input tone signal fre-
quency as the programmed frequency, pin13 goes to "Low". The signal is
input to pin16(DET) of lC107, and the squelch goes off.
When the Tone squelch decoder IC701 does not decode the input tone
signal frequency as the programmed frequency, pin13 goes to "High".
2. Encoder
The tone signal is output from pin16 of IC701, producing a frequency-
modulated RF output.
6) Microprocessor (CPU) and Peripheral Circuit
Refer to "Terminal Function of Microprocessor" about each terminal func-
tion.
1, BS ModeWhen the Squelch is closed for more than 5 seconds, the radio goes into the
BS(Battery Save) mode automatically. Pin11 (R5C) and pin19 become High
or Low periodically. Open the Squelch, and the radio does not go into the
BS mode.
2. Backup Reset
When the voltage detector circuit lC303 detects a decrease in the C5V line,
CPU RAM data is stored in the EEPROM IC, IC601. IC 302 is also the
voltage detector circuit and it detects the lower voltage than IC303. The
circuit detects a increase in the C5V line when power is turned on, and then
the CPU will be initialized.
3. Reset
Press and holdthe."F" key, then turn on the power. The radio will reset to
initial factory settings.
Even if you expanded the frequency, it will return to the initial setting. To
resume the expanded frequency, press and hold the "F" and "Lamp" keys,
then turn on the power.
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