
Model 8640B
TM 9-4935-601-14-7&P
PERFORMANCE TESTS
4-17. HARMONICS TEST (Cont'd)
AM.................................................................................................................................... OFF
FM.................................................................................................................................... OFF
RANGE ................................................................................................................. 0.5 - 1 MHz
FREQUENCY TUNE .................................................................................................. 0.5 MHz
OUTPUT LEVEL.................................................................................. +13 dBm (switch 1 step
ccw from full cw)
RF ON/OFF ........................................................................................................................ ON
2.
Set spectrum analyzer to measure harmonics 35 dB below the fundamental from 0.5 to 2 MHz. Set input
attenuation to 50 dB, resolution bandwidth to 100 kHz, frequency span per division (scan width) to 1 MHz, scale to
log (10 dB/div), and scale reference level to +13 dBm. Adjust analyzer's frequency controls to set 0 Hz to the left
edge of the display.
NOTE
If 50 dB of analyzer input attenuation is not available, use an external attenuator such as the
Model 355D.
3.
Slowly tune Signal Generator to 1 MHz, checking that all harmonics are more than 35 dB below the fundamental.
35 dB ___________________________
NOTE
If any harmonic below 512 MHz appears to be out of specification, remove any possible analyzer
error and remeasure the harmonic as follows:
a. Tune the generator to the frequency of the harmonic.
b. Using the analyzer's IF attenuator, step the signal down 30 dB on the display and note the -30
dB point on the display.
c. Step the IF attenuator up 30 dB and retune the generator to its original setting.
d. Using the -30 dB point noted on the display as a reference, remeasure the harmonic.
4.
Set spectrum analyzer and Signal Generator as shown below. On each range, set FREQUENCY TUNE to the low
end of the band and use analyzer's frequency controls to set the fundamental to the left edge of the display.
Keeping the fundamental near the left edge of the display, tune FREQUENCY TUNE to the high end of the band.
All harmonics should be as specified.
4-12
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