CIRCUIT DESCRIPTION
3-13
February 2001
Part No. 001-9800-001
Figure 3-4 RF Block Diagram (UHF Models)
T
w
o-P
ole
Bandpass Filter
T
w
o-P
ole
Bandpass Filter
45 MHz F
our P
ole
Cr
ystal Filter
L200/L201
L204/L206
Z204
RF Amp
Mix
e
r
Q201
Q202
Second Mix
er/Detector
U201
T
ripler
Q207
Z205
450 kHz
Cer
amic Filter
Q205/
Q206
Switch/In
v
e
rter
14.850 MHz
44.550
MHz
F
requency
Control
F
requency
Control
F
requency
Control
Rx A
udio
T
o
A
u
dio/Logic Bd
RSSI
T
o
A
udio/Logic Bd
Q801
Module
U806
14.850 MHz
TCXO
Ref
erence
Divider
Main
Divider
Prescaler
Control
64/65
Prescaler
Phase
Detector
Tx Modulation
Tx A
udio/Data
Shift Register
U800
VCO Control
VCO
Buff
er Amplifier
Q506
Q507
Q508
Q509
Q600
Q601
Q504/
Q505
First
Amplifier
Second
Amplifier
Third
Amplifier
Predr
iv
er
8V
T
ransmit
Switch
Dr
iv
er
Final
Antenna
Switch
Directional
Coupler
Har
m
onic
Filter
CR601,
CR603
Balance Adj
U802C
Summing Amp
Le
v
el Adjust
U802A
U802B
WB
Data
Tx
Data
Tx
A
udio
U803
U804
Batter
y
F
orw
ard
Po
we
r
Current
Sense
Po
w
e
r
Adj
U801
Channel
Prog
ra
mming
Control F
rom
A
udio/Logic Bd
P
o
w
er Amplifier Board
P
o
w
er Control
Exciter
Synthesiz
er
Po
w
e
r
Amplifier
Receiv
er
Pin
Shift
Tx F
req
Rx F
req - 45 MHz
Synthesiz
er IC
Tx Modulation
Rx F
req - 45 MHz
Antenna
Loc
k
Detect
U802D
Charge
Current
Adjust
Q204
Injection
Amplifier
Q2
Q3
Q4
Q0
Q1
fR
fV
R821
Dela
y
e
d
T
ransmit
F
rom A/L Bd
Z206
450 kHz
Cer
a
mic Filters
Z202
WB
NB
Switching
Q512
(470-512 MHz)
Q511
(470-512 MHz)
Q510
(470-512 MHz)
Q509
(470-512 MHz)
UHF SYNTHESIZER DESCRIPTION
