Motorola HT Series Service Manual page 27

7KHRU\ RI 2SHUDWLRQ 6\QWKHVL]HU
7KH UHVLVWRU QHWZRUN DW WKH LQSXW WR WKH EDVH RI WKH 4 LV VFDOHG WR WXUQ RQ 4 KHQFH DFWLYDWLQJ
WKH $*& DW FHUWDLQ 566, OHYHOV ,Q RUGHU WR WXUQ RQ 4 WKH YROWDJH DFURVV WKH WUDQVLVWRUV EDVH WR
JURXQG PXVW EH JUHDWHU RU HTXDO WR WKH YROWDJH DFURVV 5  SOXV WKH EDVHHPLWWHU YROWDJH 9EH
SUHVHQW DW 4 7KH UHVLVWRU QHWZRUN ZLWK WKHUPLVWRU 57 LV FDSDEOH RI SURYLGLQJ WHPSHUDWXUH
FRPSHQVDWLRQ WR WKH $*& FLUFXLW DV 566, JHQHUDWHG E\ 8 LV ORZHU DW FROG WHPSHUDWXUHV
FRPSDUHG WR QRUPDO RSHUDWLRQ DW URRP WHPSHUDWXUH 5HVLVWRU 5 DQG &DSDFLWRU &  IRUP DQ 5&
QHWZRUN XVHG WR GDPSHQ DQ\ WUDQVLHQW LQVWDELOLW\ ZKLOH WKH $*& LV WXUQLQJ RQ
 )UHTXHQF\ *HQHUDWLRQ &LUFXLW
7KH IUHTXHQF\ JHQHUDWLRQ FLUFXLW VKRZQ LQ
/9 )UDF1 V\QWKHVL]HU 8 DQG 9&2%XIIHU ,& 8 'HVLJQHG LQ FRQMXQFWLRQ WR PD[LPL]H
FRPSDWLELOLW\ WKH WZR ,&V SURYLGH PDQ\ RI WKH IXQFWLRQV WKDW QRUPDOO\ UHTXLUH DGGLWLRQDO FLUFXLWU\ 7KH
V\QWKHVL]HU EORFN GLDJUDP LOOXVWUDWHV WKH LQWHUFRQQHFW DQG VXSSRUW FLUFXLWU\ XVHG LQ WKH UHJLRQ 5HIHU
WR WKH VFKHPDWLF WR ORFDWH UHIHUHQFH GHVLJQDWRUV
7KH V\QWKHVL]HU LV SRZHUHG E\ UHJXODWHG 9 DQG 9 ZKLFK DUH SURYLGHG E\ ,&V 8 DQG 8
UHVSHFWLYHO\ 7KH 9 VLJQDO JRHV WR 8 SLQV  DQG  ZKLOH WKH 9 VLJQDO JRHV WR 8 SLQV 
  DQG   7KH V\QWKHVL]HU LQ WXUQ JHQHUDWHV D VXSHUILOWHUHG 9 VLJQDO WR SRZHU 8
,Q DGGLWLRQ WR WKH 9&2 WKH V\QWKHVL]HU DOVR LQWHUIDFHV ZLWK WKH ORJLF DQG $6),& FLUFXLWV
3URJUDPPLQJ IRU WKH V\QWKHVL]HU LV DFFRPSOLVKHG WKURXJK WKH PLFURSURFHVVRU GDWD FORFN DQG FKLS
VHOHFW OLQHV 8 SLQV   DQG UHVSHFWLYHO\ $ 9 GF VLJQDO IURP 8 SLQ  LQGLFDWHV WR WKH
PLFURSURFHVVRU WKDW WKH V\QWKHVL]HU LV ORFNHG
7UDQVPLW PRGXODWLRQ IURP WKH $6),& LV VXSSOLHG WR 8 SLQ   ,QWHUQDOO\ WKH DXGLR LV GLJLWL]HG E\
WKH /9 )UDF1 ,& DQG DSSOLHG WR WKH ORRS GLYLGHU WR SURYLGH WKH ORZSRUW PRGXODWLRQ 7KH DXGLR UXQV
WKURXJK DQ LQWHUQDO DWWHQXDWRU IRU PRGXODWLRQ EDODQFLQJ SXUSRVHV EHIRUH JRLQJ WR WKH 9&2 8 SLQ
 
Voltage
Multiplier
VCP
Vmult1
Synthesizer
Vmult2
U201
16.8 MHz
Ref. Osc.
Modulating
Signal
 6\QWKHVL]HU
7KH /RZ 9ROWDJH )UDFWLRQDO1 /9 )UDF1 V\QWKHVL]HU 8  VKRZQ LQ
XVHV D  0+] FU\VWDO )/ WR SURYLGH D UHIHUHQFH IRU WKH V\VWHP 7KH /9 )UDF1 ,& IXUWKHU
GLYLGHV WKLV WR  0+]  0+] DQG  0+] IRU XVH DV UHIHUHQFH IUHTXHQFLHV 7RJHWKHU ZLWK
& & & 5 DQG &5 WKH\ EXLOG XS WKH UHIHUHQFH RVFLOODWRU ZKLFK LV FDSDEOH RI
SSP VWDELOLW\ RYHU WHPSHUDWXUHV RI  WR  ° & ,W DOVR SURYLGHV  0+] DW 8 SLQ  IRU XVH
E\ WKH $6),& DQG /9=,)
Dual
Transistor
Aux3
Aux4
Loop
Filter
MOD Out
)LJXUH  8+) )UHTXHQF\ *HQHUDWLRQ 8QLW %ORFN 'LDJUDP
 LV FRPSRVHG RI /RZ 9ROWDJH )UDFWLRQDO1
Figure 2-7
Rx
TRB
Out
Rx VCO
VCOBIC
Circuit
U241
Tx
Out
Tx VCO
Circuit
Low Pass
Matching
Filter
Network
Attenuator
To PA Driver
Figure 2-8 on page 2-10

To Mixer