HP 3585A Service Manual page 82

Model 3585A
4·24. Residual Spurs
This test checks for mixing product harmonics of the
frequencies. Due to frequency offsets in the IF the exact frequency of these mixing products
is not known; therefore, a 1 kHz span is used to account for any frequency offsets.
Specification:
Procedure:
a. Disconnect all inputs to the 3585A.
b. Set the 3585A controls for:
c. Set the 3585A CENTER FREQUENCY for each of the frequencies listed in the Opera­
tional Verification Test Card for the Residual Spurs test. The average value of the marker
reading, when placed on the most positive point, should be less than - 1 20 dBm verifying that
the 3585A meets its Residual Spur specification. Record all resultant measurements on the
test card.
4·25. Harmonic Distortion
This test verifies that the harmonic distortion produced by the 3585A is less than -80 dB
below signal. The filter shown for this test removes the harmonic distortion of the sources.
This leaves only the distortion of the 3585A.
Specification:
Equipment Required:
Procedure:
a. Connect the output of the 3585A Tracking Generator to the input of the 9 MHz Low
Pass Filter. Connect the output of the filter to the 3585A 500 input. (See Figure 4-21 for the
9 MHz Low Pass Filter Schematic.)
b . Compare the displayed trace with that of Figure 4-21 . This will confirm that the filter is
operating properly.
<
Residual Responses
INSTRUMENT PRESET
REFERENCE LEVEL . . . . . . . . . . . . . . . . . -75 dBm
RES. BW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Hz
VIDEO BW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Hz
RANGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -25 dBm
MANUAL SWEEP . . . . . . . . . . . . . . . . . . . . . . . . on
FREQUENCY SPAN . . . . . . . . . . . . . . . . . . .
<
Spurious Responses -80 dB below signal
9 MHz Low Pass Filter . . . . . . . . . . (see Figure 4-21)
Frequency Synthesizer . . . . . . . . . . . . . . . -hp- 3335A
90
MHz and 10 MHz internal reference
- 1 20 dBm
l
kHz
Performance Tests
4-23