Tektronix WFM700 Series, Service Manual

Page: 127 / 194

Adjustments
WFM700 Series Waveform Monitors Service Manual
3- 19
This procedure sets the calibration constant for the eye diagram clock recovery
bandwidth. This calibration routine is only available for the WFM700M
(WFM700 with a WFM7M 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,
741.7582 MHz, 800 mV into
75
8
, with 10 Hz jitter
modulation
With the recommended RF generator, you can generate the
required signal with the following settings to obtain 10 Hz
jitter modulation.
Frequency 741.7582 MHz
Output Level 0 dB
LFGEN2 Frequency 10 Hz
LFGEN2 Waveshape SINE
Phase Modulation Source LFGEN2
Phase Deviation 2.22 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.
e. Press the INPUT button and select Input A .
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.
Touch the
Eye Loop BW Adjust (10 Hz)
soft key and then the
Start Eye
Loop BW Adjustment (10 Hz) soft key.
4. Adjust the RF generator output level for a displayed waveform amplitude of
approximately 800 mV.
5. Adjust the displayed modulation using the General Purpose Knob for exactly
1 UI as measured on the display. See Figure 3--13.
6.
Touch the
Save and Exit
soft key to save the new calibration constant.
Eye Loop BW Adjust
(10 Hz)