Alinco DR-150T, Руководство по обслуживанию, Страница: 3 / 45

CIRCUIT D E S C R I P T I O N
1) Receiver System
1. Preamp, Mixer Circuit
2. IF and AF Circuit
2) Transmitter System
1. Modulation Circuit
The signal from the a n tenna is passed through a low -pass filte r and input to
L 2 1 1. The signal from L211 is led to the base o f Q 208. T h e signal from
Q 208 is led to th e triple band pass filte r (L212, L213, L214), and gets the
high im age rejection ratio. The signal from the triple band p a ss filter is
converted into the first IF signal of 45.1 MHz. The receiving signal is led to
the gate 1 of Q 209, and the first local oscillator signal is led to the gate 2 of
Q209. T o reduce the high a d ja ce n t channel interference, the band width of
the X203 is set to 20kHz. The signal from X 203 is am plified by Q214, and
input to FM IF system IC201 o fT K 1 0 9 3 0 .
The TK 10930 has the second local oscillator circuit, m ixe r circuit, detector
circuit, squelch circuit, and so on. Pin1 and 2 are th e te rm in a ls of the crystal
oscillator circuit. Pin3 o f IC201 is connected to CFW 201 d ire ctly because
the m atching resistor for ceram ic filte r is built-in. T h e q u a d ra tu re circuit
(p in l 1 of IC201) is connected to the L221. The signal from pin12 of IC201 is
connected to th e LPF. The de te cte d A F signal, w hich has flat frequency
characteristics, is led to the control unit and used as both squelch signal and
tone squelch signal. D e-em phasis circuit consists of R 257, R258, C 282 and
C284. The am plifier consisting of Q 2 1 5 and Q 217 is located fa r aw ay from
the VR in the control unit, so it o u tp u ts the high voltage signal to prevent S/N
from the deterioration. The squelch switch circuit co n s is ts of Q 2 1 6 and
Q 235, and sw itches o n /o ff at th e p o in t w here there is no vo lta g e to prevent
from the sw itching noise. The S m eter signal from pin16 o f IC201 is led to
the C PU in the control unit after adjusting the level at V R 206. T h e noise
am plifier consists of p in l 9 and 20, the built-in O P a m p lifie r in IC 2 0 1 . The
output signal o f noise am plifier is am plified by Q218, rectified by D216, and
then led to the pin21 (hysteresis co m p a ra to r input) o f IC 2 0 1 . IC 202 is about
5W audio pow er am plifier IC.
The m icrophone am plifier IC 501(ID C , LPF) consists o f fo u r operational
am plifiers. The signal from the m icrophone is led to a m p lifie r circ u it consist­
ing of IC 501C and then input to th e pre-em phasis circu it co n sistin g of C 503.
And then input to the lim ite r circuit IC501B. T he lim iter circ u it uses the
saturation of the OP am plifier. T h e am plified signal is in p u t to th e low-pass
filter IC501A. T he output signal is led to am plifier circu it c o n sistin g of IC502,
and the signal is passed through variable resistor V R 204 fo r m odulation
adjustm ent and input to the V C O unit. Sub tone signal is in p u t to th e low-
pass filte r IC501D. S ub tone deviation is determ ined by V R 205.