Flatness
Out
of
T
olerance
The
output
level
atness
of
the
tracking
generator
is
specied
at
a
010
dBm
output
power
setting
(vernier
set
to
0
dBm,
attenuator
set
to
010
dB).
In
general,
most
atness
problems
result
from
a
failure
in
the
A2
tracking
generator
microcircuit.
However
the
POWER
L
VL
signal
from
the
A3
interface
assembly
and
the
LO
INPUT
signal
from
the
host
spectrum
analyzer
can
also
contribute
to
atness
problems
.
1.
Check
the
function
of
the
POWER
L
VL
signal
from
the
A3
interface
assembly
.
a.
Set
the
tracking
generator's
OUTPUT
LEVEL
vernier
to
a
level
at
which
the
atness
is
out
of
tolerance
.
b.
Monitor
A3U5A
pin
1
with
a
DVM
while
stepping
the
CENTER
FREQ
from
100
MHz
to
2.9
GHz
in
100
MHz
increments
.
c.
Plot
the
voltage
variation
versus
frequency
.
d.
A
discontinuity
in
the
plot
near
the
frequency
at
which
the
atness
is
out
of
tolerance
indicates
a
problem
on
the
host
spectrum
analyzer's
0.5
V/GHz
OUTPUT
.
2.
Check
the
atness
of
the
LO
INPUT
signal.
a.
P
erform
the
1ST
LO
OUTPUT
amplitude
performance
test
for
the
host
spectrum
analyzer
.
b.
If
the
spectrum
analyzer
passes
this
test,
the
fault
most
likely
is
with
the
A2
tracking
generator
.
c.
If
the
spectrum
analyzer
fails
this
test,
determine
the
equivalent
CENTER
FREQ
setting
at
which
the
power
level
was
out
of
tolerance
by
subtracting
3.9107
from
the
1st
LO
frequency
.
Compare
the
result
with
the
frequency(ies)
at
which
the
atness
was
out
of
tolerance
.
d.
Repeat
the
test
with
the
power
sensor
connected
to
A2J3
(remove
A
T1)
noting
the
equivalent
center
frequency
of
any
out-of-tolerance
power
levels
.
e.
The
power
level
should
be
+14.5
dBm
63
dB
.
f.
If
the
power
level
is
acceptable
at
the
spectrum
analyzer's
1ST
LO
OUTPUT
but
out
of
tolerance
at
A2J3
and
the
CENTER
FREQ
setting
of
the
out
of
tolerance
power
levels
is
close
to
the
frequencies
that
caused
the
unleveled
condition,
suspect
A2.
g.
If
the
power
level
at
the
1ST
LO
OUTPUT
is
also
out
of
tolerance
,
suspect
the
host
spectrum
analyzer
.
3.
Check
all
coax
cables
,
especially
semirigid
cables
.
A
fault
in
one
of
these
cables
can
cause
a
very
high-Q
power
hole
.
HP
85640A
RF
T
racking
Generator
Operation
and
Service
Manual
Service
Information
7-27
Содержание 85640A
Страница 2: ...HP 85640A RF Tracking Generator Operation and Service Manual ABCDE Printed in USA ...
Страница 111: ......
Страница 169: ......
