Agilent Technologies E8257D, User Manual

Page: 145 / 318

Chapter 4 131
Optimizing Performance
Using External Leveling
Figure 4-2 External Detector Leveling with a Directional Coupler
Configure the Signal Generator
1. Press
Preset
.
2. Press
Frequency
>
10
>
GHz
.
3. Press Amplitude > 0 > dBm .
4. Press
RF On/Off
.
5. Press
Leveling Mode
>
Ext Detector
.
This deactivates the internal ALC detector and switches the ALC input path to the front panel
ALC INPUT connector. The
EXT indicator is activated in the AMPLITUDE area of the display.
NOTE For signal generators with Option 1E1, notice that the
ATTN HOLD
(attenuator hold)
annunciator is displayed. During external leveling, the signal generator automatically
uncouples the attenuator from the ALC system for
all external leveling points. While in this
mode, the RF output amplitude adjustment is limited to
−
20 to +25 dBm, the adjustment
range of the ALC circuitry. For more information, see “External Leveling with Option 1E1
Signal Generators” on page 133 .
6. Observe the coupling factor printed on the directional coupler at the detector port. Typically, this
value is
−
10 to
−
20 dB.
Enter the positive dB value of this coupling factor into the signal generator.
7. Press
More (1 of 2)
>
Ext Detector Coupling Factor
>
16
(or the positive representation of the value listed at
the detector port of the directional coupler) >
dB
.
Leveled output power is now available at the output of the directional coupler.
NOTE While operating in external leveling mode, the signal generator’s displayed RF output
amplitude is affected by the coupling factor value, resulting in a calculated approximation of
the actual RF output amplitude. To determine the actual RF output amplitude at the point of
detection, measure the voltage at the external detector output and refer to
Figure 4- 3 or
measure the power directly with a power meter.
Determining the Leveled Output Power
Figure 4- 3 shows the input power versus output voltage characteristics for typical Agilent