Samyung SRG-315DN, Руководство пользователя

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12.2. CONTROL CIRCUIT (T-1110)
The Control Circuit consists of MF/HF TX/RX circuit, Local Synthesizer circuit, Power circuit and CPU circuit.
(1) MF/HF RX Circuit
< RX BLOCK DIAGRAM >
RX method is a Double Super-heterodyne receiver
using two intermediate frequencies, 1'st
IF=49.455MHz and 2'nd IF=455 KHz.
Receiving signal in whip antenna pass BPF of 9
bands, then after amplify in RF (Q-53) and
in 1'st MIXER (MX2), it is mixed with 1'st LOCAL
frequency and demodulated to a first intermediate
frequency and the intermediate frequency goes
through 49.455MHz X-tal filter (XL5,6) and IF
amplifier (Q22) and
in 2'nd MIXER (MX1), it is mixed with 2'nd LOCAL
frequency and demodulated to a second
intermediate frequency and the demodulated
frequency goes through 455KHz X-tal filter (FL3)
and IF amplifier (Q21,Q23,Q950) and
In 3'rd MIXER (IC15), it is demodulated to a
signal of baseband with BFO (Beat Frequency OSC.).
The demodulated signal is divided to 3 species as
follows.
①
Amplifiable signal for inner speaker audio.
②
Amplifiable signal for outer speaker audio.
③
FSK MODEM (DSC Signal Demodulation) Signal.
(2) MF/HF TX Circuit
< TX BLOCK DIAGRAM >
The baseband signal comes from MIC or NBDP
terminal is mixed with BPF, 2'nd LOCAL frequency
each in MIXER_3, 2 (IC9, MX1) and goes through
each intermediate frequency filters 455KHz (FL3),
49.455MHz(XL1,XL2), each amplifier (Q36,Q35),
then is modulated to each intermediate frequencies
and the modulated 1'st LOCAL frequency in a final
MIXER_1 (MX2) goes through LPF (Low Pass Filter),
BPF of 9bands and then, is input to Power Amplifier
(T-1113) and the sufficient amplified signal in PA
(Power Amp) goes through a final TX filter (T-1111)
and at this time, the harmonic wave (Harmonics) is
removed and the signal comes out thru an antenna.