Agilent Technologies 83640B - Page 261

1.
10 MHz
Standard
Description
and Procedure
This pro
cedure adjusts
the frequency
accuracy of
the in
ternal
10
MHz
time
base.
This
adjustmen
t
should
b
e
done
on
a
regular
basis
if
absolute
frequency
accuracy
is
imp
ortant
(see
Figure
3-3
.)
F
or
best
accuracy,
readjust the
10 MHz
timebase
oscillator
after
the
syn
thesizer
has
b
een
on
or
in
standb
y
for
24
hours.
See
\Accuracy
V
ersus
Adjustmen
t
In
terv
al,"
follo
wing this
adjustmen
t,
for
information
on
ho
w
to
determine
ap
erio dic
adjustment
schedule.
After
the
timebase
is
adjusted,
the
timebase
frequency
should
sta
y within
the aging
rate if
the
follo
wing things
happen:
The
time
base
o
v
en
do
es
not
co
ol
do
wn.
The
instrumen
t
k
eeps
the
same
orien
tation
with
respect
to the
earth's
magnetic
eld.
The
instrumen
t
sta
ys
at
the same
altitude.
The
instrumen
t
do
es
not
receiv
e
an
y
mec
hanical
sho
c
k.
If the
time
base
o
v
en
co
ols
(the
instrumen
t
is
disconnected
from
A
C
p
o
w
er),
you
may
hav
e
to
readjust
the
time
base frequency
after a
new w
arm-up cycle.
T
ypically
,
ho
w
ev
er,
the
time
base
frequency
returns
to
within
6
1
Hz
of
the
original
frequency
.
Note
Y
ou
can
adjust
the in
ternal
timebase
after
reconnecting
A
C
p
o
w
er
for
10
min
utes,
but
for
b
est
accuracy
,
test
again
after
the instrumen
t
has
b
een
on
or
in
standb
y
for
24
hours.
F
requency c
hanges,
due
either
to
a
c
hange
in
orien
tation
with
resp
ect
to
the
earth's
magnetic
eld
or
to
a
c
hange
in
altitude,
are usually
eliminated when
the
instrumen
t
is
returned
to
its
original
p
osition.
A
frequency
c
hange
due
to
mec
hanical
sho
c
k
usually
appears
as a
xed
frequency
error.
3-4 Adjustments
10 MHz Standard
Agilent 8360