HP 8340B Manual page 75

4-15.
AMPLITUDE MODULATION TEST (Cont'd)
7. Press
the DUT's
[POWER LEVEL]
key and enter
[+] [5] [dBm]. Press
the
[AM]
key to turn
AM
OFF. Repeat steps
3
through
6
for this power setting.
8. Press the
DUT's [CW] key and enter [4] [.]
[5] [GHz].
Press the
[AM] key to turn AM OFF. Set the
power meter's
calibration factor switch
to include 4.5 GHz. Repeat
steps
3
through
6
for
DUT
power
settings
of
—5 and
+5
dBm.
AM FREQUENCY RESPONSE AND BANDWIDTH
9. Disconnect
the power sensor and connect the DUT's RF output to the 20 dB attenuator.
10.
On the
DUT, press
[CW] [1] [.] [5] [GHz], [POWER LEVEL] [0] [dBm].
On the LO, press
[INSTR PRESET] [CW] [1]
[.]
[4] [5] [GHz], [POWER LEVEL] [1] [0]
[dBm]. Press PEAK (ON). (The
output may be
unleveled; this
will
not affect the test.) The IF frequency
is
now
50 MHz.
NOTE
For best accuracy in the Amplitude Modulation test, the Local Oscillator
drive to the mixer should be
>
+4
dBm.
11.
Set
the function generator for
a
sine
wave
at
a
reference frequency of
1
kHz at 0.2121 Vrms
(0.3
times 0.707)
±0.05
Vrms. For example: 0.25 Vrms, as indicated
on
the DVM, would
fall
in this
range.
Set
the modulation analyzer input frequency
to 50
MHz
(by pressing FREQ 50 MHz), then
press AM and AVE. The modulation analyzer should
indicate about 21%.
Note the DVM
indication.
12. Press the dB key. As the modulating frequency
is changed, the modulation analyzer will indicate
the flatness in dB relative to the
1
kHz
reference.
13.
Set the function generator to
100,200,500 Hz, then
1,2,5,
and 10 kHz. Check the DVM
indication
and adjust
the level of the modulating signal at each
frequency
to eliminate any flatness error of
the function generator. Observe the flatness indication on the modulation
analyzer. The
flatness
indication should be
s ± 0.20 dB.
14.
Check the
AM bandwidth by setting the function generator to 100 kHz. Adjust the function gener¬
ator output level to the value noted in
step
11.
The modulation analyzer should indicate 2: —3 dB-
AM DEPTH
15.
Set the function generator to
1
kHz. Set the
modulation analyzer to indicate percent modulation by
setting the controls as follows:
AUTOMATIC OPERATION
............................................
ON
AM
..............................................................
ON
RATIO %
..........................................................
OFF
RATIO dB
.........................................................
OFF
PEAK
...................................................,...........+
Increase
the function
generator output amplitude to obtain
>90%
modulation depth.
16. Repeat steps
11 through 15 at DUT RF
frequencies of
3,9,15, and,
if the DUT
is
an
HP 8340B, 22
GHz.
Make
sure LO CW
frequency
is
always 50
MHz below the
DUT frequency.
4-74 Performance Tests
HP 8340B/41B