Icom IC-R7O Maintenance Manual page 20

3. 2nd loop
This loop is a mixed-down type PLL loop composed of IC7, IC8, Q10 and 014.
This output passes through the low-pass filter composed of L21 and C100 ~ C102, and is then fed to pin
7 of IC8 again. Then, after amplification at the amplifier circuit in IC8, it is fed from pin 9 through Q10 to
pin 3 of IC7.
LOQOOP® Sv 5v
8v ciss DA
R65
30.9514 MHz
30.8515 MHz
Te
30,.720MHz
IC7 is a phase comparator; the reference frequency (131.5 ~ 231.4 kHz) divided to 1/100 the 3rd loop
output by IC5 is applied to pin 1.
Pulses produced by the phase-difference of the two signals injected to pin 3 and pin 1 are output from
pin 5 and pin 10, pass through the loop filter composed of R57 ~ R59 and C93, and are provided as
control voltage for D13.
LOGIC UNIT 8v
Rig LIi2
c109 R66 | 39.6 ~
° 69.5MHz
6 jei2cita v26
ak:
ah 2nd LOOP
i
9 30.8515 ~ 30.9515 MHz
L27
Lea4aciil L25Cci
70.4515 ~ 100.4515 MHz
8v