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PR-8210-A
5. CIRCUIT DESCRIPTIONS
5-1
RFAM
RFAM
consists
of
PHDB
(photo
detector
is an
emitter
follower.
The
RF
OUT
signal
is
board) and HEDA
(head amp) is mounted on the
extracted from this point.
slider assembly. The photo detector mounted on
The four focus control signals are B1 thru ВА.
PHDB
picks
up
the
various
signals,
and
after
The sums of B1 and B3, and the sums of B2 and
passing them
through a filter choke
to eliminate
B4 are sent to their respective OP amps (Z2) where
the 620MHz
spurious signal generated by the laser
they
are
amplified
about
17dB,
then
output
as
tube, outputs them to HEDA.
FOCS
А and
FOCS B signals.
Tracking
controi
The FM
signal is amplified by about 20dB by
signals À and C are input to the voltage-follower
the negative feedback
amp. Transistors
Q1 and Q2
type
OP
amp
71, and
extracted
as TRKG
A and
form
a cascade connected amplifier stage, and Q3
ТЕКС B output signals.
HEAD AMP.
В,
|
+
+
Amp
a
-
FOCSB
|
DETECTOR
|
4—]
amp
=
=
0 FOCS A
Amp
E
Emiter
—O
RF OUT
follower
|
Negative feedback amplifier
Voltage-
follower
Е
ТАКС
А
Vottage-
=
follower
P тако в
ЯРАМ
BLOCK
DIAGRAM
Fig. 1
RFAM block diagram
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