HP 8340b User Manual

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

HP 8340b Specifications

General

Brand	HP
Model	8340b
Category	Inverter
Language	English