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Model
8672A
Adjustments
ADJUSTMENTS
5-33.
20/30 MHz
(LFS)
Loop Divider
Bias
Adjustments
REFERENCE:
Service Sheet
1-A2.
DESCRIPTION:
A
clock
signal
derived
from
an
external
RF
signal source
is
monitored
with
an oscillo¬
scope.
The RF
signal level
is
slowly reduced and the
CLK
BIAS
ADJ
is
set
to obtain
a
stable
clock
signal.
The
RF
input
is
reduced to the
minimum
level
that
provides
a
stable signal.
OSCILLOSCOPE
TO A2A5J2
160-240
-N
INPUT
A2A5
SIG
ASSEMB.LY
SYNTHESIZED
SIGNAL GENERATOR
Figure 5-11.
20/30 MHz
Loop Divider
Bias
Adjustment Test Setup
EQUIPMENT:
PROCEDURE:
HP
180C/1801A/1821A
HP
8654A
Oscilloscope.
.
Signal
Generator
1.
Disconnect the Mains power
cable and set the
LINE ON-STANDBY
switch
to
STANDBY.
2.
Remove
the screws
that
hold the
A2A5 20/30 MHz
Divider Assembly
in place.
WARNING
Because this
circuit board
is
being
placed on an extender board,
the possibility
of
coming in contact
with
GO
Vdc
is
greatly in-
increased. Be
careful while working on the circuit
boards
with
power
supplied.
Work with
one hand.
Do not
touch the extender
board.
3.
Remove
the
A2A5
Assembly, place
it
on an extender board, and reinstall the
assembly.
4.
Connect the power
cable
to the power module.
Set the
LINE
ON-STANDBY
switch to ON.
5.
Set
the
signal
generator controls for cw output of
—5
dBm
at
240 MHz.
6.
Remove the red
cable
A2W2 from
the 160—240
MHz INPUT A2A5J1.
5-23
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