
5-16.
LEVELED RF OUTPUT ADJUSTMENTS
(Cont’d)
LINEAR MODULATOR ALC LOOP GAIN ADJUSTMENTS
Description
The following adjustments are performed to set the ALC loop gain for each band. The adjustment is
done in the power sweep mode, while sweeping the ALC loop from —20 to maximum power.
NOTE
If the A26 Linear Modulator assembly has not been replaced, adjust-
ments may not be necessary.
23. Connect CHAN A of the oscilloscope to A26TP3 (MOD LVL). Connect CHAN B to A25TP2 (DET).
Set up the oscilloscope as follows:
DISPLAY
CHOP
CHAN
A
O.05V Div DC COUPLED
CHAN B
O.05V/Div DC COUPLED
TRIGGER
EXT. POS.
TIME/Div
5 inS
SWEEP VERNIER
ON
24. On the OUT, press [INSTRPRESET] [SWEEPTIME] [5] [0] [msec]. Press [SHIFTI[PWRSWP]
[-1[2] [0] [dBm]. Press [PWRSWP] [4] [0] [dBm].
Press [SHIFT]
[CF][2] [0] [0] [MHz] and then
[AM] to turn AM on. Press [CW] [1] [0] [MHz].
The oscilloscope display should be similar to Figure 5-56, Waveforms A and B. It may be neces-
sary to adjust the SWEEP VERNIER to view the entire sweep.
HP 8340B/41B
Adjustments
5-107