A33J1 Output Check (With Phase Lock Loop Closed) - HP 8340B Manual
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18.
Perform the
M/N
Loop adjustment
in
Section
5,
Adjustments, of
the Calibration Manual.
If,
during
the procedure, you are unable
to adjust the
VCO
for the correct
frequency and power (measured
at A32A1W1), replace the A32 assembly. At step
17
of the
M/N
Loop adjustment procedure,
record
the frequency at
A32A1W2 when
the TP1
(TUNE)
is
set to
-2.8V
and
-35V.
After
this,
reconnect
A32A1W1 and measure the frequency and power out of A33J1 and A33J2 when
TP1 is
set
to
-2.8V
and
-35V.
A33J1 should be at
the
same
frequency as A32A1W1 and
A33J2
should
be
one
half the
frequency of A32A1W1.
If
either output
is
incorrect, replace A33.
19. If,
upon completion of the
M/N
Loop adjustment procedure, the
M/N
loop
is still
not
operating
properly, switch the
DUT
to
STANDBY
and
remove the
A31
assembly
from the instrument (an
extender board should
still
be installed). Connect
a
jumper cable
from A31
P1
pin
6
(VCO TUNE
—)
to
pin
5
(GND).
Set
the
power
supply to
-1V
and then connect the
DVM
to TP1 (TUNE). Connect
the positive
lead
of the power supply to
pin 5
(GND)
and the negative lead to pin
21
(VCO TUNE
+).
Switch the DUT on and
verify that TP1
is
approximately —38V (A33 input loop amplifier
railed
negative).
If this
test fails, replace the A33 assembly.
NOTE: "Railed"
refers to the condition
in
which an amplifier
is
at the positive or negative operational
limit
determined by
its
power
supplies and biasing circuitry.
20. Switch the
DUT
to
STANDBY
and
disconnect the power
supply.
Remove
the
jumper from
A31P1
pin
6
(VCO TUNE
-)
and reconnect
it
to
pin
21
(VCO
TUNE
+).
Connect the positive lead of the
power
supply to
pin
5
(GND)
and the
negative lead to
pin
6
(VCO TUNE
—).
Switch the DUT ON
and verify that
TP1
(TUNE) measures approximately —0.5V (A33
input loop amplifier railed
positive).
If
this test fails, replace
A33.
If
steps
19 and
20
both pass,
replace
A31.
A33J1 OUTPUT
CHECK (WITH
PHASE LOCK LOOP CLOSED)
Test
Setup
ON
THE
DUT:
Press
[INSTR PRESET] [CW] [4] [5] [3] [0] [MHz]
(M
and
N
divide
numbers
=
24).
Connect
the
10
MHz
REF output
to the spectrum
analyzer's FREQ REFERENCE
input.
Connect an SMB(f) to SMB(f)
cable to A31J1.
Split A31J1's output signal with
a
SMB Tee.
Connect A31W2 to one output of the tee
and the other output to the
spectrum analyzer's
input.
ON THE SPECTRUM ANALYZER
As shown
in
the figures on the following page.
B-28
M/N
Loop
Assembly-Level Troubleshooting
HP 8340B/41B
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