HP 8340B Manual page 78

4-16.
FM ACCURACY AND FLATNESS (Cont'd)
4. On the
function generator, press
AMPTD 450 mV
(p-p).
Then press the
LEFT ARROW
key until
the
first
digit on the
left side of the decimal point is
flashing.
5.
Set the spectrum analyzer's center frequency to that of the DUT.
Choose
a
frequency span of
2
MHz.
Observe the carrier
on the display of the
spectrum analyzer while performing
step 6.
6.
Press the
function generator's UP ARROW
or
DOWN ARROW
keys until the carrier
is nulled
(minimum amplitude). The function
generator's LEFT ARROW
and
RIGHT ARROW
keys
will
change the
resolution of the UP ARROW
and
DOWN ARROW keys
for
a
finer or coarser amplitude
adjustment.
7.
Measure
the rms amplitude of the FM input with the
DVM. Note
this value on the
test record card
as
V,^.
Calculate the actual FM sensitivity and then the percent error. Actual deviation
is equal to 2.404
times
100
kHz (since the modulation index is at the first
Bessel
Null).
The actual
FM
sensitivity
is
then:
Actual FM Sensitivity
=
(.2404)/(V,n
x
1.414)
%
Error
=
100
x
(Actual FM Sensitivity
-
Range)/Range
Where "Range"
=
1
(for
1
MHz/V),
or
10 (for 10
MHz/V).
8.
Set the function
generator's amplitude
to 45
mV
p-p. Press the DUT's the UP
ARROW
key to
select an
FM
sensitivity of 10
MHz/V. Repeat
steps
6
and
7.
9.
Repeat steps
4
through
8
at
CW
frequencies of
2.5,6.9,13.4,18
and 20
GHz
(20
GHz applies
to the
8340B
only).
After entering
a
new CW
frequency, press
the FM key twice to display
the FM
sensitivity in
the
DUT's ENTRY DISPLAY
and
then press the DUT's DOWN
ARROW
key to select
an
FM sensitivity of
1
MHz/V.
HP 8340B/41B
Performance Tests 4-77