Anritsu 682XXB, 683XXB 2-16 682XXB/683XXB MM

NOTE
Theinstrument uses two internal level de-
tection circuits. For frequencies <2 GHz
(£2.2GHz for 682X5B/683X5B models), the
level detector is part of the Down Con-
verter. The signal from this detector is
routedto the A10 ALC PCB as the Detector
0input. For frequencies ³2 GHz (>2.2 GHz
for 682X5B/683X5B models), the level de-
tector is part of the main Directional Cou-
pler.The signal from this detector is routed
to the A10 ALC PCB as the Detector 1 in-
put.
The Level Reference DAC, under the control of the
CPU, provides the RF level reference voltage. By
setting the output of this DAC to the appropriate
voltage, the CPU adjusts the RF output power to the
level selected by the user.Leveled output power can
be set over a maximum range of up to 28 dB (up to
131 dB with the optional 110dB step attenuator)
using front panel controls or the GPIB. Instruments
with Option 15B (High Power) provide leveled out-
put power over a maximum range of up to 22 dB (up
to 125 dB with the optional 110dB step attenuator).
External Leveling
In the external leveling mode, an external detector
or power meter monitors the RF output level of the
682XXB/683XXB instead of an internal level detec-
tor.The signal from the external detector or power
meter goes to the A10 ALC PCB from the front or
rear panel inputs. The ALC controls the RF power
output level as previously described.
ALC Slope
During analog sweeps (683XXB only), a slope-vs-
frequency signal, from the A12 Analog Instruction
PCB, is summed with the level reference and detec-
tor inputs into the ALC loop. The Slope DAC, under
the control of the CPU, adjusts this ALC slope sig-
nal to compensate for an increasing or decreasing
output power-vs-frequency characteristic caused by
the level detectors and (optional) step attenuator.In
addition, the Slope DAC lets the user adjust for the
slope-vs-frequency characteristics of external com-
ponents.
2-16 682XXB/683XXB MM
FUNCTIONAL ALC/AM/PULSE
DESCRIPTION MODULATION