Motorola TALKABOUT T2688, Service Manual

Page: 69 / 77

2
1
DIPLEXER
U113
RX SIGNAL PATH
TX SIGNAL PATH
MAIN VCO SIGNAL PATH
TUNING VOLTAGES
REFERENCE CLOCK
1805-1880MHz
Orderable Part
Non - Orderable Part
935-960MHz
U604
DCS: 1710-1785MHz
GSM SERVICE SUPPORT GROUP 01.01.11
LEVEL 3 RF Block Diagram Rev. 1.3
Dual Band Topaz
Michael Hansen, Ray Collins, Ralf Lorenzen-Scheil Page 1 of 2
RX VCO
U606
TX VCO
225 MHz
PCS:1850-1910MHz
GSM: 890-915Mhz
DCS: 1710-1785MHz
GSM:1335 - 1359Mhz
DCS: 1580 - 1655MHz
DCS: CH 700 -- 1842,8MHz
RX MID CHANNELS
GSM: CH 62 -- 947,4 MHz
DCS: CH 700 -- 1612.8MHz
RX VCO MID CHANNELS
GSM: CH 62 -- 1172.4MHz
RX VCO FRQ. RANGE
TX VCO MID CHANNELS
GSM: CH 62 -- 902.4MHz
TX VCO FRQ. RANGE
TX FRQ. RANGE
D
u
a
l
B
a
n
d
T
o
p
a
z
270 MHz
45 MHz
LC TANK
U603
HD155121F
PGA
RXI
RXQ
SYNTHESISER
IC
ANT 1
CALIBRATION
RF PORT
9
5
7
8
11 6 3
10 8 2 4
PA_ON
VBAT
BS
14
CONTROL SWITCH U502
IC501
7
6 & 12
U602
GSM_RX
DCS_RX
Q601
Q602
b
e
c
b e
c
3
U601
1
2
GSM_RX
DCS_RX
47
48
RXON1
RXON2
U401 1
5 3
4
2
BS
SYN2V8
IC401
8
LO1
39
42
43
29
30
IF_TUNE
D601
540MHz@GSM
135Mhz@DCS
33
45MHz
6
1
24
25
20
21
22
23
IF_TUNE 7
To VEGA
To VEGA
TX_ON
44
45
46
From GEMINI
BS 35
To U603
From Synthesiser
TXI
TXQ
13
14
15
16
2
1
BS
SEE PAGE 8 / 9 OF LEVEL 3
CIRCUIT DESCRIPTION
11
8
9
90 deg
45 MHz
TX_DCS
TX_GSM
90
o
TX LOOP
FILTER
6
1
TX2V8
10
5
U605
Diplexer
5
1
3
TX_GSM
TX_DCS
U201
PA
2
4
12
10
6
8
U202
PA CONTROL
BS
BS
16
RAMP
From VEGA ( RAMPDA )
3
5
+ -
1 4
VBAT
14
R203 VBAT
0.033Ohm
4
1
2
3
5
6
TXON
VBAT
Q201
TXVCO_OFF
GSMPA
DCSPA
G
S
M
P
A
D
C
S
P
A
11 1
CONTROL
FUNCTION
From VEGA
From VEGA
U402
1 AFC
From VEGA
3 4
VTCXO From U27
Power Management IC
1
13MHz
D
A
T
A
S
Y
N
P
R
G
C
L
O
C
K
13 14
15
From Gemini
SYN2V8 4
LO2 To Synthesiser
LO2
From U603
11
3
RF2V8 32 41
AGCPRG
16
17
6
VBAT
RF_ON
TX2V8 RF2V8
SYN2V8
RF POWER SUPPLY
IC901
From VSYNEN (Gemini)
7 3, 4
1 2
8
TX / RX IC
TX / RX Switch
U501
36
AGCPRG
DATA
CLK
4
5
RF_OUT
RFIN1
RFIN2
Control
Logic
T
h
is
l
in
e
is
I
n
te
rn
al
t
o
t
h
e
T
X
/R
X
I
C
T
h
is
l
in
e
is
I
n
te
rn
al
t
o
t
h
e
T
X
/R
X
I
C
From Gemini
Serial
Interface
28
27
26
SYNPRG
GSM - 124 Channels
25MHz B/W
200Khz Spacing
GSM
DCS
DCS: CH 700 -- 1747.8Mhz
See Circuit description Page 2 for Logic
Control truth table.
4
1
2
3
5
6
Q202
PA_ON
R298
1,2-1,5V
IC402
from IC901
to Gemmini
&
Vega
270MHz@GSM
135Mhz@DCS
GSM
DCS
VC1
VC2
VC3
VC4
R209
R208