SECTION 4 OPERATING INSTRUCTIONS
4.5.6 Special Functions Related to Level
The signal generator offers the following functions as special functions related to the setting of output levels. You
activate these functions through the "System (2)" menu.
(1) Level Safety Mode
This unit uses a mechanical attenuator to vary the output level. For this reason, momentary signal interruptions
and spike noise may be produced when you vary the output level.
In the measurements where a spike-like high level poses a particular problem, the level continuous mode described
in Paragraph 4.5.4 will be a solution for you. However, if you need to vary the level over a wide range, you will
have to opt for the level safety mode described in this paragraph.
This level safety mode requires that you once narrow the level and then set up a level again, before you can vary
it. This necessarily involves momentary signal interruptions, and affects the level setting time, but does not give
rise to spike-like high level.
(2) Display of voltage unit
The voltage of the output level is displayed in two ways: terminated-voltage display and open-voltage display.
The terminated-voltage display indicates a voltage that holds when a 50 Ω resistance is coupled to the output end,
and the open-voltage display shows a voltage that exists when the output end is left open. The open voltage
assumes a value twice that of the terminated voltage.
To execute a special function related to the output level, follow the procedure detailed below.
(3) Isolation mode
When using multiple signal generators with the summed output signal for the measurement of the inter-modulation
distortion of an amplifier etc., the inter-modulation distortion of the summed output signal may disturbs the
measurement due to the interfererence between the signal-generator outputs of low isolation.
In this case, it is desired to increase the signal isolation between the signal generators for suppressing the distortion.
The MG3641A/MG3642A has the isolation mode to increase the isolation by increasing the attenuation amount
of the last-output-stage circuit.
This isolation mode has the following advantages and disadvantages. Understand these features before use.
•Advantages: Improves intermodulation distortion.
Improves floor noise.
•Disadvantages: Deteriorates output level accuracy.
Deteriorates higher harmonic distortion.
Deteriorates AM modulation characteristics.