Amplitude Modulation Envelope Distortion - HP 3336A Operating Manual

Performance Tests Model 3336A/B/C
4-31. Amplitude Modulation Envelope Distortion.
- 4-32. This procedure verifies that the -hp- 3336 meets the Amplitude Modulation Envelope @
Distortion specification listed in Table 4-1.
Specification:
All distortion related sidebands will be more than 30 dB below the first or fundamental
sideband at 80% modulation. fe = 20 MHz, fm = 10 kHz.
Required Equipment:
Sine Wave Source -hp- Model 3325A
Spectrum Analyzer -hp- Model 141T/
8552B/8553B
50-75 ohm Minimum Loss Impedance
Matching Pad -hp- Model 85428B
a. Connect the equipment as shown in Figure 4-11.
b. Set the 3336 (DUT) controls as follows:
SIGNAL: OUTPUT i66i cd ecantitintaen isis ta cee ests 75 ohm
AMPLITUDE sisson shied Fabia tenis seeks +7.00 dBm
FPREQUENCY seve cei s oi Paes Ae Rae eaew tees 20 MHz
AMPLITUDE. MODULATION 0 :ci3 vo ssiad cee eee ee On
c. Set the spectrum analyzer controls to display the carrier (center frequency = 20 MHz)
and at least four orders of sidebands (frequency span = 100 kHz). &
d. Set the frequency of the modulating signal to 10 kHz. Adjust the amplitude of the
modulating signal until the first sideband is 7.96 dB below the carrier amplitude. This side-
band to carrier relationship correpsonds to 80% amplitude modulation. Note, as the percent
of modulation increases, the amplitude of the carrier will decrease slightly. This is normal
and due to the 3336's leveling loop regulating the output power at a constant level.
SPECTRUM ANALYZER
arerr
sas) sf} oou ous] 44 porto
J od I
24) 55555
2 J/ 4p po 44
762
AMPTD ~hp- 3336 (DUT) | CUTPUT
INPUT
75/50
SINE WAVE SOURCE 50/75 1. MINIMUM.
LOSS IMPEDENCE
MATCHING PAD
OUTPUT (50)
Figure 4-11. Amplitude Modulation Envelope Distortion Equipment Set Up.
4-34