HP 8340b User Manual

9.
Is
the
YO
Frequency
Change Porportional to
YO
TUNE?
Record
the
actual
YO
frequency.
Disconnect
YO
TUNE
and
FM
COIL
DRIVE, cables
A49J1
and
A49J2. Place
a
50^1
load
on
the
YO
TUNE
cable,
A49J2.
(These
cables
will
remain
disconnected
for
the
remainder
of
the
troubleshooting.)
Note
the
YO
frequency now
and
compare
it
with
the
value
recorded before
the
cables
were
removed.
It
should
have changed
10
MHz
or
less.
The
YO
frequency
sensitivity
to
YO
TUNE
is
approximately
—3.0
MHz/V.
If
the
frequency
does
not
change,
or
if
it
changes
by
more
than
10
MHz,
this
indicates
a
problem
on
the
ASS
YO
driver.
If
the
frequency
change
is
proportional
to
the
YO TUNE
voltage,
proceed
to
the
next
step.
10.
Is the
Open-Loop
YO
Frequency
Accuracy
±
5
MHz
at
2.300
and
6.999
GHz?
With
the
YO
TUNE
and
FM
COIL
cables
disconnected
(and
a
50^ load
on
the YO
TUNE
cable,
A49J2), the
YO
frequency
accuracy
should be
within
a
±5
MHz
window
over
the
entire
YO
operating
range.
The
YO
accuracy
should be
checked at 2.300
and
6.999
GHz.
If
the
actual
YO
frequency
is
outside
of
these limits,
go
to
step
17;
if
not,
proceed
to
step
11.
11.
Is
Sampler
IF
Frequency
and
Power
Correct?
Check
for
the
correct frequency
and
power
for
the
SAMPLER
IF.
The
frequency
accuracy
(open
loop)
should
be
±5 MHz,
the
same
as
the
YO.
If
the
SAMPLER
IF
frequency
and
power
are
correct,
suspect
the
A49
YO
loop phase detector;
if
not
correct,
proceed
to
question
12.
12.
Is
RF
Power
into
the
A48
YO
Loop
Sampler
Correct?
Check
the
RF
signal
power
into the
A48 YO
loop
sampler.
If
the
RF
power
is
correct,
troubleshoot
the
A48 YO
loop
sampler.
If
no
signal
is
present
or
if
the
power
is
incorrect,
proceed
to
question
13.
13.
Is
Directional
Coupler
Power Output
at
A45J2
Correct?
Check
the
coupled-back
RF
power
out
of the
A45
directional
coupler
at
A45J2.
If
no
signal
is
present
or
the
power
level
is
incorrect,
replace
the
A45
directional
coupler.
If
the
RF
power
is
correct,
check
the
AT215
dB
attenuator,
the
A46
7
GHz
low
pass
filter,
and connecting
cables.
14.
Is
Directional Coupler
Power
Output at
A45J3
Correct?
This
portion
of the
troubleshooting guide
is
a
branch
from
question
2.
Check the
RF
power
out
of
the
A45
directional
coupler
at
A45J3.
If
the
signal
is
present
at
the
correct
power
(Refer
to Figure
D-6,
2
of
2),
then
a
problem also
exists
in the
main
RF
path
(RF
Section).
To continue to
troubleshoot
the
YO
UNLK,
however, go
to
question
3.
If
no
signal
is
present
or
if
the
power
output
is
low,
proceed
to
question
15.
15.
Is
YO
Power
Output Correct?
Check
the
RF
power
out
of
the
YO.
If
the
power
is
correct
(Refer
to
Figure
D-6,
2
of
2),
trou¬
bleshoot
the
A45
directional
coupler.
If
no
signal
is
present
or
if
the
power
is
low,
proceed
to
question 16.
HP 8340B/41B
YO
Loop
Assembly-Level Troubleshooting
D-17

HP 8340b Specifications

General

Brand	HP
Model	8340b
Category	Inverter
Language	English