5-18.
PULSE ADJUSTMENTS (Cont’d)
17. Set up the pulse generator for a
25
kHz, 5 Vpk (10 Vp-p), square wave.
18. Set the oscilloscope as follows:
DISPLAY
CHANNEL A
CHAN A
005 V/Div (AC)
CHAN B
2.0 V/Div (50 Ohm)
TRIGGER
CHAN B
TIME/Div
5 j.tsec
19. On the HP 8340B (Option 006), press [CWJ[1] [GHz][POWERLEVEL] [5] [dBm][SHIFT][AM]
[SHIFT][PULSE].
20. Adjust A26R7 (BAL) and A25R58 (BAL) full clockwise. The oscilloscope display should look sim-
ilar to Figure 5-68, waveform a.
21. Adjust A25R58 (BAL) for an oscilloscope display as shown in Figure 5-68, waveform b.
22. Adjust A26R7 (BAL) for an oscilloscope display as shown in Figure 5-68, waveform c.
SLOW PULSE MODULATION FINE ADJUSTMENT
23. Connect the equipment as shown in Figure 5-69. Connect the mixer directly to the local
oscillator’s RF output to obtain the maximum LO drive to the mixer. Connect the BNC tee directly
to the OUT’s PULSE connector. Allow 30 minutes for the instruments to warm up.
24. Set the oscilloscope as follows:
DISPLAY
CHANNEL B
CHAN A
0.1
V/Oiv, 50 Ohms
CHAN B
5 V/Oiv, 50 Ohms
TRIGGER
INT., CHAN B
TIME/Div
5 usec
25. Set up the pulse generator for a 25 kHz (8 divisions on the oscilloscope), 5V peak (10 V p-p) square
wave. The damage level for the OUT’s PULSE input is +12V —20V so do not overdrive the input.
26. On the OUT, press [INSTR PRESET] [CW] [2] [GHz] [POWER LEVEL] [0] [dBm] [SHIFT]
[PULSE].
NOTE
For best accuracy in this test, the LO drive to the mixer should be> + 4
dBm.
27. On the LO, press [INSTRPRESET] [CW] [1]
[.] [9] [5]
[GHz] [POWER] [LEVEL] [1] [0] [dBm].
28. Press DISPLAY A on the oscilloscope. Adjust A21 R30 (LSYM)
so
that the 50% points on the pulse
envelope cover four vertical graticules on the oscilloscope (50% duty cycle).
29. On the OUT, press [CWJ[3] [GHz]. On the LO, press [CW] [2]
[.]
[9] [5] [GHz]. Adjust A21R29
(HSYM) so that the 50% points on the pulse envelope cover four vertical graticules on the
oscilloscope (50% duty cycle).
5-126
Adjustments
HP 8340B/41B