Rise And Fall Time Adjustment - HP 8672S Operating And Service Manual

Adjustments
Models 8672S/86720A
ADJUSTMENTS
5-8. RISE AND FALL TIME ADJUSTMENT (cont'd)
Procedure
(cont'd)
4. Set potentiometer AlRl 4 (+PW) fully clockwise. Adjust counterclockwise to obtain
the bias pulse waveform shown in Figure 5-5.
5. Set potentiometers A1R7 (-P) and A1R12 (-PW) to the center of their ranges. Adjust
A1R12 (-PW) for a pulse width of 7 ns on the negative pulse at A1TP17.
6. Connect oscilloscope and diode detector to the .01 TO 18.0 GHz OUTUT of the FEU.
Set pulse generator's pulse width to about 100 ns.
7. Set Signal Generator to 3 GHz.
8. Set FEU pulse mode to _n~ (normal).
9. Adjust potentiometer A1R7, "-P", for the shortest RF pulse fall time.
10. Verify that the rise and fall times are less than than 15 ns.
11. Set Signal Generator to 18 GHz and verify the rise and fall times are as before. If the
rise time is greater than 15 ns, change A1R18 to 1800 ohms. Readjust the "+PW"
potentiometer as in step 4 and repeat the rise time test. Verify that no power dip in
RF pulse waveform occurs with the new resistor.
5-8