HP 83751A, Руководство пользователя

Страница: 40 / 282

Externally leveling the Sweeper
leveling with detectors/couplers/splitters
Some external leveling applications require low output power from the
sweeper. The sweeper automatically uncouples the attenuator from the ALC
system for external leveling points. Note that in external leveling modes,
the UNCPLD annunciator is lit.
For example, leveling the output of a 30 gain amplifier to a level of
10 requires the output of the sweeper to be around -40 when
leveled. At some frequencies this level is beyond the range of the ALC
modulator alone. If so, the UNLEV warning message is displayed. Inserting 40
of attenuation results in an ALC level (power level + attenuator value) of
0 which is well within the range of the ALC. This gives a margin for
AM or other functions that vary the power level.
The ALC level should be greater than or equal to -10 for “A” model
sweepers (standard power), and -5 for “B” model sweepers (high
power). Adjust the attenuator so that the ALC level is within the specified
power range of your sweeper. For an “A” model sweeper, this is achieved by
using attenuation equal to the tens digit of output power. Example: for a
desired sweeper output power of -43
do the following:
Press SPECIAL
2. Set the attenuator to 40 press
To obtain flatness corrected power refer to the chapter entitled “Creating User
Flatness Correction Arrays, later in this manual.
2-6