Yaesu FT-227R Memorizer, Инструкция по эксплуатации

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OPTIONAL TONE SQUEL C H C IR C U IT
The Tone Squ el ch ope ration pe rmits p rivate c ommuni c ations on
c rowded channel s . The tone s quelch cir cuit di s able s the audio
cir cuit of r e c eiver until a p r e s et tone si gnal i s r e c eived .
The tr ansmi tted s i gnal i s modulated by the to ne s i gnal within
70 Hz to 2 5 0 Hz which i s below the 3 0 0 Hz to 3 0 0 0 Hz voi c e
frequency rang e us ed in radio communicati ons.
The tone s ignal is gene r ated by Q 5 0 2 , N E S 67 and its fr equ ency
i s s et by R 5 1 6 , VR 5 0 2 and C 5 1 6 . The l evel of the tone s i gnal i s
s et by VR5 0 4 and i t i s fed t hrough a buffe r amplifi e r Q 5 0 3 , 2 SK19 GR
to the low -pa s s filte r consi s ting of unit ''d'' o f an ope r ati onal amplifi e r
Q 5 0 1, M C 3 40 3 . The tone s i gnal i s then sup e rimpo s ed to the s pe e ch
s i gnal by Q 2 0 2 . The cons tants fo r p r e s et fr equency a r e obtained from
the chart .
The audio output s i gnal from the r e c e iver di s c riminato r i s fed to the
unit "a" o f Q 5 01 , MC 3 40 3 . The unit "a" of Q 5 01 fo rm s a hi gh -pa s s
filte r and the unit "b" of Q 5 01 fo rms a T -notch filte r . Both filte r s
r emove the tone s i gnal from the audio s i gnal whi ch i s then fed through
an audio amplifi e r Q 5 0 5 , 2 S C 3 72 Y to the r e c eive r audio amplifi e r Ql 11 .
The tone s ignal pa s s e s through a low pa s s filte r by unit
"c"
o f Q 5 01 and
i s fed to Q 5 02 , NE S 67 . When the tone s i gnal ha s the s ame fr equency
a s p r e s et fo r transmitting , the volta g e of pin 8 of Q 5 0 2 be c ome s low
c au s ing Q 5 04 , 2 S C 3 72 Y to "O F F " . In turn , proper bi a s voltage i s
applied t o Q 1 19 fo r no rmal op e r ation .
Without p r op e r tone s i gnal , Q 5 04 c onducts , r emoving the p rop e r bia s
from Q 119 to di s able the audio c i r cuit.
As the c o nventional c a r ri e r s quelch c i r cuit is oper ative when the tone
s qu elch i s s witched in , the bu s y lamp li ghts up when any c a r r i e r i s
r e c e iv ed.
( S w Al
I
I
I
oso>
I
I
I
I
I
I
I
(TONE SQ SWITCH)
TONE SQUELCH(PB-1555A> OPTION
F i gu re 9
I
I
- 20 -
C516
*
70Hz
I 0.15µF
160Hz
160Hz
I O.lµF
250Hz
* * * *
R 516 R 513
R 514 R 524
39K0 15K0 470K0 15KO
33K0 8.2K0 270K0
s.2Kn
Table 2