Tektronix WFM700 Series, Service Manual

Page: 123 / 194

Adjustments
WFM700 Series Waveform Monitors Service Manual
3- 15
This procedure adjusts the scale factor for the SD jitter display and the measured
jitter readout. This adjustment is only available for the WFM700M (WFM700
with a WFM7M video module).
Following is a list of the signal requirements to perform the adjustment.
Adjacent to the requirement is the recommended equipment and test signals.
Adjustment requirements Recommended test equipment and test signal
Calibrated sine wave generator,
135 MHz, 800 mV into 75
8 , FM
modulated to generate 2 UI jitter
amplitude
RF generator adjusted to 800 mV output into 75 8 at the
requested frequency.
You can adjust the output amplitude of the RF generator by
measuring the output level with the test oscilloscope
terminated into 75
8 .
With the recommended RF generator, you can modulate the
signal with the following settings to obtain 2 UI of jitter.
Frequency 135 MHz
Frequency Modulation OFF
LFGEN2 Frequency 10 kHz
LFGEN2 Waveshape SQUARE
Phase Modulation Source LFGEN2
Phase Deviation 3.14 RADIANS
RF Output ON
Phase Modulation ON
75 8 coaxial cable 36 inches long
NOTE
. If this test is performed out of sequence or the sequence of tests has been
interrupted (such as power off or input from another module was selected),
perform the steps in this note to prepare the instrument to continue testing.
a. Connect the SD video generator to INPUT B using a 75
8
cable.
b. Set the SD video generator for a 525-format 100% color bar signal.
c.
Press the
INPUT
button and select
Input B
.
d. Press the EYE button.
1. Install the 50
8
N-to-BNC adapter on the RF generator output.
2. Connect the RF generator output to INPUT A using a 75
8
cable. Imped-
ance matching is not important for this connection.
3. Press the INPUT button and select Input A .
SD Jitter Gain Adjust