External Leveling Used With the Optional Step Attenuator
Some external leveling applications require low output power from
the swept CW generator. The swept CW generator automatically
uncouples the attenuator from the ALC system for all external
leveling points.
Press
(
P O W E R LEVEL
).
Note the display. It shows:
0
POWER LEVEL: 0.00
For example, leveling the output of a
gain amplifier to a
level of -10
requires the output of the swept CW generator
to be around -40
when leveled. At some frequencies this
level is beyond the range of the ALC modulator alone. If so, the
LOW UNLVLED warning message is displayed. Inserting 40
of
attenuation results in an ALC level of 0
which is well within
the range of the ALC. At 20
30
attenuation is a better
choice as it results in an ALC level of -10
This gives a margin
for AM or other functions that vary the power level.
For optimum display accuracy and minimum noise, the ALC
level should be greater than -10
This is achieved by using
attenuation equal to the tens digit of output power. Example:
desired output power -43
use:
40
ALC -3
1. Press POWER
2. Select Set
Hint
To obtain flatness corrected power, refer to “Creating and Applying
the User Flatness Correction Array” in the “Optimizing Swept CW
Generator Performance” section.
1-26 Getting Started Advanced
