Stanford Research Systems DS335, User Manual

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Function Setting 2-9
DS335 Synthesized Function Generator
DS335 OPERATION
Introduction The following sections describe the operation of the DS335. The first section
describes the basics of setting the function, frequency, amplitude, and offset.
The second section explains sweeps and FSK. The third section explains
storing and recalling setups, running self-test and autocalibration, and setting
the computer interfaces.
Power-On When the power is first applied to the DS335 the unit will display its serial
number and ROM version for about three seconds. Then, the DS335 will
initiate a series of self-tests of the circuitry and stored data. The test should
take about three seconds and end with the message "TST PASS". If the self
test fails the DS335 will display an error message indicating the nature of the
problem (see the TROUBLESHOOTING section for more details). The
DS335 will still attempt to operate normally after a self-test failure, pressing
any key will erase the error message.
SETTING THE FUNCTION
OUTPUTS The FUNCTION and SYNC BNCs are the DS335's main outputs. Both of
these outputs are fully floating, and their shields may be floated relative to
earth ground by up to ±40V. Both outputs also have a 50
Ω
output
impedance. If the outputs are terminated into high impedance instead of 50W
the signal levels will be twice those programmed (the FUNCTION output may
also show an increase in waveform distortion). The output impedance should
be set properly from the front panel using the [SHIFT][5] or [SHIFT][6] keys.
Incorrect impedance matching may result in output voltages that do not
correspond to the displayed amplitudes and offsets. For example, if the
DS335 is set for a 50 Ohms source impedance and the output is connected
to a scope without a 50 Ohms terminator, then the scope waveform will be
twice the amplitude displayed on the DS335.The programmed waveform
comes from the FUNCTION output, while the SYNC output generates a TTL
compatible (2.5 V into 50
Ω
) signal that is synchronous with the function
output. The SYNC signal is suppressed if the function is set to NOISE or
ARB. The SYNC signal can be disabled and enabled with the [SHIFT][0] and
[SHIFT][.] keys.
FUNCTION SELECTION The DS335's output function is selected using the FUNCTION UP/DOWN
arrow keys. Simply press the keys until the desired function LED is lit. If the
programmed frequency is outside of the range allowed for the selected