Yaesu FTV-901R, Инструкция по эксплуатации, Страница: 16 / 42

50 MHz UNIT
The 50 MH z signal from the antenna is fe d thro ugh
a lo w-pa ss filter, consisting of C323 , C324 , L312,
an d L313 , to RL301. On receive, the signal i s ampli­
fie d by Q20 s
(3SK51)
an d fed thro ugh a selective
bandpass filt er, which is tune d to the operating
fre quency by varactor dio de s D210 an d D211
(1S2209).
The secon d gate of Q1os is connecte d
through a large re sistor to the front panel RF
GAIN control, allo wing variation in the gain
of the RF amplifier.
The signal i s then fe d to the mixer, Q106
(3SK51 )
,
where the 50 -5 4 MH z signal is mixe d with a local
signal of 2 2 or 24 MH z, pro ducing an IF signal of
28 -30 MH z which i s fe d through a diode switch to
the 10 M OUTPUT jack.
The local signal i s generate d by crystal o scillator
Q207
(2SC784R),
an d amplifie d by Q1os
(2SC784R).
For repeater operation, th e local
signal is shift ed up or down 1 MHz, according to
the position of the front panel R PT switch.
For tran smi ssion, the 28- 30 MH z outp ut signal
from the transceiv er i s fe d to the balanced mixer,
Q101
(MC1496G),
where it i s mixe d with the local
signal delivere d from Q208. The 50 -5 4 MH z signal
is then passe d thro ugh a selectiv e ban dpa ss fil ter,
which effectively eliminate s spurious signal s. Th e
signal i s then amplifie d by the amplifier chain,
consi sting of Q102
(3SK51),
Q103
(2SC2053),
Q104
(2SC730)
QJ01
(2SC2166),
an d Q302
(2SC19450).
The output signal of approxi­
mately 10 watt s i s then fe d, via a lo w pass filter, to
the ANT jack.
A portion of the o utp ut from Q301 i s det ecte d by
D303 an d D304
( 1Sl555),
an d the re sul ting DC
voltage is amplifie d by Q111
(2SC1815Y)
for ALC
purpose s. A portion of the outp ut from L311 i s
detecte d by D3o6 an d fe d to the base o f Q111,
controlling the bia s of Q111 and Q302 . Q11 o
(2SC1815Y)
works a s a switch f or the automatic
final protection circuit, which will reduce the gain
of the amplifier tran si stor s in ca se of high SWR.
A f urther portion of the output is detecte d by
D3os
(1Sl555)
an d fe d to the meter, for an
in dication of relative po wer output.
Q3o9
(78L08)
reg ulates the supply voltage at 8
volt s for the tran si stor s.
I 6M UNIT
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50-52MHz 22MHz C
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