Yaesu FT-227R Memorizer, Инструкция по эксплуатации

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The s e cond
IF
circuit con s i s ts of Ql 0 6 , Ql07 , Ql 0 8 , (2 S C 3 7 2 Y ) and
Ql09, (p.P C 5 7 7 H) . The c a s c ad e conne c ted c e r ami c filte r s C FlOl and
C F 1 0 2 p r ovide na r r ow band s el e ctivity fo r the r e ceive r and the limit ­
ing a c ti on of Ql09 r emove s any amplitud e va riation to the c e rami c
di s criminato r c on s i s ting o f CDlOl , D l 0 6, and Dl 0 7 , (1Sl 8 8FM) .
The dis c r iminato r produc e s an audio output in re sponse to a
c o r r e s ponding fr e quency s hift in the I F s ignal . The output audio
s i gnal i s amplified by Qll 3 , Qll4 , (2 S C 3 7 2 Y ) and is applied a c ro s s
the VOLUME c ontrol VRl to the input o f the audio amplifi e r Q11 6 ,
(p.
P C 5 7 5 C 2 ) . The output from Qll 6 i s appli ed in s e rie s through the
A C C s o cket to the inte rnal s p e ak e r . The low-pa s s filte r betwe en
Qll 3 and Qll4 attenuate s the audio fr equency spectrum above 3 kHz
to inc r e a s e r e adability of the r e c eived s ignal .
A p o r tion of the 4 5 5 kHz I F s ignal i s rectified by D l 0 3 , Dl04 ,
(1Sl 8 8FM) fo r S -me te r indi c ation . VRl Ol i s u s ed to adju s t th e me te r
s en s itivity .
When no c a r rie r i s p r e s ent in 4 5 5 kHz I F , the hi gh fr e quency noi s e
a t the di s c riminato r output i s amplified by QUO and Qlll , (2 SC372Y) then
dete c ted by Dl08 and Dl09, (1Sl 8 8FM) to produc e a DC volta g e . Thi s
volta g e i s then applied to tu rn Qll2 , (2S C 3 7 2 Y ) on . With the condu c -
ti on of Qll2 , the b a s e of Qll 3 is g r ounded to s quelch the audi o ampli ­
fi et . '\\rhen a c a r ri e r i s p r e s ent in the 4 5 5 kHz I F , the noi s e i s r emov ­
ed from the dis c riminato r output and the audio amplifie r the n r e c ov-
e r s normal o p e r ation .
The s quelch ci r cuit op ening c au s e s Qll 3 to condu c t , c au s ing lamp
drive r Qll 5 , (2 S C 3 7 2 Y ) to d r aw cur r ent to li ght up the BUSY LAMP .
The SQUE L C H control s , VRZ and V:Rl02, s et the threshold level.
HE TERODYNE OSCILLA T O R
T h e he te r ody:ne s i gnal i s g e ne rated by the PLL (pha s e lock l o o p )
c ir cuit cons i s ting of VCO (voltag e c ontrolled o s c illato r ) , r e fe r ence
c r y s tal o s cillato r , p r o g r ammabl e divid e r and pha s e c omparato r .
The V C O o s cill ator , Q 3 01 ( 2 SK19GR) gene rate s 13 3 . 3 -1 3 7 . 3 MHz
s i gnal s . The o s cillato r fr e quency i s controll ed by a va r a cto r
diode D 3 01 , (1S 2 2 0 9 ) whi ch va rie s the c apa citance of a tuned
cir cuit c on s i s ting o f L 3 01 , T C 3 01 , C 3 0 2 and C 3 04 in a c co rdanc e
with a D C volta g e suppli ed from a pha s e c omparato r Q 3 0 9 ,
(T C 5 0 81P ) .
The output s i gnal from Q 3 0 1 i s amplifi ed by a buffe r amplifi e r
Q 3 0 2 , ( 3 SK 4 0M) and Q 3 0 3 , (2S C 5 3 5A ) and fe d through a diode
switch, D 3 0 2 and D 3 0 3 , (1Sl 5 5 5 ) to the r e c e ive r o r tran:s mitte r
mixe r s .
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