HP 8340B Manual page 185

5-14. UNLEVELED RF OUTPUT ADJUSTMENTS (Cont'd)
If the output power begins to decrease while adjusting one of these potentiometers (pots) clock-
wise (i.e., power reversal, squegging), adjust the pot counter-clockwise until the power is peaked
again and then continue turning the pot counter-clockwise until the power is reduced
It may be desirable to optimize the power in one half of the band (maximum power with no
squegging), even though squegging is induced in the other half. One would do this if the side being
adjusted is significantly lower in power than the other half. Once the power is optimized, adjust the
bias in the other half (using the pot for that half) to eliminate squegging. Iterate between the two
adjustments to optimize the power and to ensure that there is no squegging in either half.
Adjust A28R99 (BP1) to peak the power in the second half of the display.
19.
20. Access Cal Constant 73 by pressing [SHIFT] [GHz] [7] [3] [Hz] [SHIFT][ENTRYOFF] on the
OUT. Using the OUT's rotary knob, adjust Cal Constant 73 to peak the power across the entire
band (adjust above and below 1024). Repeat steps 19 and 20.
21. Repeat step 18.
22. Note the position of the minimum power point on the scope. On the OUT, press [MANUAL].Adjust
the OUT's rotary knob until the dot on the scope is near the position noted as the minimum power
point. Slowly vary the position of the dot around this point while observing the OUT's POWER
dBm display. The minimum power displayed should be> 1 dB above the maximum leveled power
specification for the OUT in Band 3 (13.35 to 20 GHz). If this is not the case, disconnect the
detector from the OUT and connect the power meter and power sensor. Again, slowly vary the
rotary knob and determine the power level of the minimum power point. If it is still <1
the maximum leveled power specification, press [CONT]on the
22.
Band 4 Adjustments (HP 834GB Only)
If adjusting an HP 8341 B, proceed to step 31.
23. On the OUT, press
[STARTFREO] [1] [9]
[STOPFREQ] [2] [6]
[CONT]
[SAVE][1]
Adjust the scope's vertical position and/or sensitivity to display the swept RF output.
24. Adjust A28R24 (BP2 FREQ) to peak the power across the band. If this adjustment has no effect or
reduces the power, return A28R24 to full clockwise and proceed immediately to step 26 (step 25
will not be required).
25. Adjust A28R25 (BP3 FREQ) to peak the power in the second half of the display. If A28R25 has no
effect or reduces the power, return the pot to full clockwise. Adjust A28R27 (BP2) to peak the
power across the band. If A28R25 (BP3 FREQ) was adjusted from full clockwise, adjust A28R28
(BP3) to optimize the power in the second half of the display.
26. If the trace goes off the oscilloscope display in the following adjustments, adjust the vertical
position and/or sensitivity controls to view the entire trace on the display.
Adjust A24R9 (X4A) to optimize the power in the first half of the display.
HP 8340B/41B
[8] [GHz]
[.]
[5] [GHz]
[.]
dB
and repeat steps 17 through
OUT
Adjustments
0.5 dB.
above
5-79