HP 3585A Service Manual page 70

Model 3585A
4·1 5. 501750 Frequency Response Test
In this test the 500 and 750 flatness of the instrument is checked against the output of the in­
ternal calibrator. The display shows the Tracking Generator switched through the internal
calibrator, which is assumed to be flat, sweeping across the frequency range of the instru­
ment. The maximum and minimum points of the sweep are measured. This gives the total
deviation of the 3585A 50 or 750 input relative to the flatness of the calibrator.
Specification:
Frequency Response, Terminated Input: ± 0.5 dB referenced to 20. 1 MHz
Procedure:
a. Set the 3585A controls for:
b. Press the SINGLE SWEEP button on the 3585A.
c. Wait until the sweep is completed. The trace you now see is the flatness of the 500
input.
d. Move the marker to the center of the trace.
e. Set the 3585A controls for OFFSET on and ENTER OFFSET.
f. Using the marker, find the point on the trace which gives the greatest positive or
negative deviation as shown by the marker amplitude reading.
g. The marker amplitude reading displayed is the greatest deviation from the calibrator
flatness for the range shown. Record this value under Maximum Amplitude Deviation on
the Operational Verification Test Card.
h. Set the 3585A controls for RANGE . . . . . . STEP UP.
i. Repeat Steps b thru h until all ranges have been tested.
j . Set the 3585A controls for:
RECALL 604
INSTRUMENT PRESET
START FREQUENCy . . . . . . . . . . . . . . . . 0. 1 MHz
STOP FREQUENCY . . . . . . . . . . . . . . . . 40. 1 MHz
REFERENCE LEVEL . . . . . . . . . . . . . . . . . -20 dBm
dB/DIV . . . . . . . . . . . . . . . . . . . .
REF L VL TRACK . . . . . . . . . . . . . . . . . . . . . . . . . off
RANGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . -25 dBm
.
VIDEO BW . . . . . . . . . . . . . . . . . . . . . . . . . . . 300Hz
RANGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -25 dBm
INPUT IMPEDANCE . . . . . . . . . . . . . . . . . . . . 750
SINGLE SWEEP
l
. . . . . . . . . . . dB
.
Performance Tests
4-1 1