HP 8340b User Manual

3.
Check the
M
divider
frequencies as
follows:
a.
On the
DUT, press
[INSTR PRESET] [CW]
[2]
[4]
[9] [0]
[MHz].
Select
a
step
size
of
10
MHz
by
pressing
[SHIFT]
[CF]
[1]
[0]
[MHz].
Press
[SHIFT]
[M1]
to
display,
from
left
to
right,
the
M
divide
number,
the
N
divide
number,
the
M/N
loop
output
frequency
(M/N
OUT),
and
the
20/30
loop
output
frequency.
Press
[CW]
to
display
the
CW
frequency
in
the
ENTRY
DISPLAY.
b.
Press
[^]
and
step
the DUT
down
to 2300.000000
MHz.
Check the
counter
indication
at
each
step.
The
counter
should indicate
the M/N
loop output
frequency
±2 Hz.
If,
at
any
point,
the
frequency counter
does
not
indicate
the
M/N
loop
output
frequency
displayed
on
the
DUT,
record
the
DUT's
CW
frequency
and
proceed
to
step
1
of the
M/N
Output
Frequency
Incorrect
troubleshooting
below.
4.
Check
the
N
divider
frequencies
as
follows:
a.
Select
a
step
size
of
200
MHz
by
pressing
[SHIFT]
[CF] [2]
[0] [0]
[MHz].
Press
[CW]
to
display
the
CW
frequency
in
the
ENTRY
DISPLAY.
The
CW
frequency
should
be
2300.000000
MHz.
b.
Press
[•*]
and
step
the
DUT
up
to
6900.000000
MHz.
Check
the
counter
indication
at each
step.
The
counter
should indicate
the
M/N
loop
output
frequency
±2 Hz.
If,
at
any
point,
the
frequency
counter
does not
indicate the
M/N
loop output
frequency
displayed
on
the
DUT,
record
the
DUT's CW
frequency
and
proceed
to
step
1
of
the
M/N
Output
Frequency
Incorrect
troubleshooting
procedure,
below.
5.
If
steps
3
and
4
both
passed,
the M/N
loop
is
phase-locked.
Press
[SHIFT]
[EXT].
The
following
phase
lock
loop
diagnostic should
be
displayed
in
the
ENTRY
DISPLAY:
OSC: REF
M/N
HET YO
N2
N1
If
M/N
is
flashing,
the M/N
loop is
unlocked.
Proceed to step
8.
If
M/N
is
not
flashing,
proceed
to
step
6.
6.
Connect
a
power
meter
or
spectrum
analyzer
to
A33J2.
Repeat
steps
3
and
4.
The
power
level
indication
at
each step
should
be
3
dBm
±3
dB.
If
the
output
power
is
low at
any
point,
perform
the
M/N
Loop adjustment
procedure
in
Section
5,
Adjustments,
in
the Calibration
Manual.
If
you
are
unable to
adjust
A32C5
(PWR)
for
0
dBm
±2
dB
out
of
A32A1W1
(355
-
395
MHz output)
replace A32.
If
the
power
out
of
A32A1W1
is
good,
replace
A33.
7.
If
steps
3
through
6
pass,
the M/N
loop
is
operating
properly.
8.
Switch
the
DUT
to STANDBY. Place
the
A31
assembly
on
an
extender
board and
reconnect any
A31
SMB
cables.
Remove
the
A59
digital
interface
assembly
from
the
instrument
and switch
the
DUT
ON.
9.
Measure
the
voltage
at
A31
P1
pin
26.
The
voltage
at
A31
P1
pin
26
should
be
approximately
—0.7V
(note:
if
the
voltage
is
0V,
the
feedthrough
capacitor
on
the
reference
loop
—
M/N
motherboard
may
be
shorted).
If
the
voltage
is
incorrect,
replace
A31.
If
the
voltage is
correct,
proceed
to
step
10.
10.
Switch
the
DUT
to
STANDBY
and
reinstall
the
A59
digital
interface
assembly.
Switch
the
DUT
ON
and
again
measure
the
voltage
at
A31P1
pin
26.
If
the
voltage
is
no
longer approximately
—0.7V,
remove
the
A59
digital
interface
and check
the
motherboard
connector,
A62XA59,
for
bent
pins.
If
none
of the
pins
are
bent,
replace
A59.
If
the
voltage
at
A31P1
pin
26
is still
approximately
—0.7V,
troubleshoot
the
A59
assembly for
a
false
unlock
indication.
B-22
M/N Loop Assembly-Level
Troubleshooting
HP
8340B/41B

HP 8340b Specifications

General

Brand	HP
Model	8340b
Category	Inverter
Language	English