3·2 Pll Circuits - Icom IC-R7100 Service Manual

3·1·27 TIMER CONTROL CIRCUIT
(MAJN UNIT)
013 controts a relay circuil (RL2) for Ihe timer function .
The CPU (ICS, pin 34) on Ihe LOGIC UNIT outputs a
"HIGH" signal
w~en
the [TIMER] switch is pushed
OUT. The " HIGH" signa I is applied 10 013 through Ihe
" POC" line and lurns RL2" ON.
3·1 ·28 REGULATOR CIRCUIT (MAIN UNIT)
ICtO
is a
voltage regulator providing a slabje 9 V 10 tne
MAIN and RF UNITs.
3·2 PLL CIRCUITS
3·2-1 GENERAL
The PLL circuit oscillales a 1st LO frequency (778.7000
-1291 .6999 MHz) tor Ihe lsl mixer circuil on Ihe MIX1
UNIT and a 2nd LO frequency (2S6 or 768 MHz) tor Ihe
2nd mixer c ircuil on Ihe MIX2 UNIT. The IC-R7100
uses a helerodyne down converter PLL system . The
heterodyne down converter PLL system employs a mixer
circuit in Ihe PLL loop circu it to cut oft Ihe high
tre-
quency components by mixing Ihe frequencies when
the VCO frequency exceeds Ihe maximum frequency
that the PLL IC can divide.
• PLL CIRCUIT
389.35 -645.84995MHz
IC6
r---------,
I
vcoi
389.35 _ 514.3995
I
1
I ,
I
1
v-
05
I
I
01,02
1
15,16 CHARGE
I--l
LOOP FILTER
1--..., 1 ,...,
H 1--,
PUMP I I
I
VCQ2
02,03 IC2.0 " ,OS. 06 514.35 -645.84995
I
I "" I
I
DW
I
I
03 .0'
I
I
VCO UNI T -
I
1
...J
P .o
" N
•
IC'
10kHz
I
PRE -
SCALEA
I-__
~~~:=;~== ~
1164.1/65
"
10 .n
ose
3<3.2 ~
J.43.20995MHz
12.8MHz
11.
IC6
IC10
r - - - - - j
L
_ - -f I - 01
I
I
X2
i
I
IC10,02
I
I
01,02
36.000 -
1~~~~J
36..'MHZ
...1..
• -
( "'~-- ~ 12 MHZ.
DIA
COl1YeI'tet'
xr
151
ro
!Slgnal
178.7.....
1291.6999MHz
307.2MHz
X3
017
ose
""
016
r-_ _ .::;'53.8MHZ
I
I"!!:"lo'
V
010
X2
01'
X5
0 20
768.tltr.lHI.
X3
022
Fig. 10
3 -10