Stanford Research Systems DS345, Manual

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Performance Tests
5-7
3) Verify that the DS345's output is within ±6% of the 1kHz amplitude for fre-
quencies less than 20 MHz, and within ±15% for frequencies from 20 to 30
MHz.
DC OFFSET ACCURACY
This test measures the accuracy to the DS345's DC offset function.
DC Only
specification: 1.5% of s 0.2mV
1) Connect the DS345's output to the voltmeter with a 50
Ω
terminator. Set
the DS345 to 0.0V amplitude
2) Set the DS345 to 5V offset. Read the voltmeter and record the result.
The result should be b4.925V and +5.075V.
3) Set the DS345 to -5V offset. Read the voltmeter and record the result.
The result should be between -5.075V and -4.925V.
4) Set the DS345 to 0V offset. Read the voltmeter and record the result.
The result should be between -0.2 mV and +0.2mV.
DC+AC
specification: < ±80mV at full output
1) Connect the DS345's output to the voltmeter with a 50
Ω
terminator. Set
the DS345 to sine wave, 1 kHz, 10Vpp, 0V offset. Set the voltmeter to meas-
ure DC voltage.
2) Measure the offset voltage and verify that it is between -80mV and
+80mV. Record the result.
3) Repeat step 2 at 100kHz, 1MHz, 10 MHz, 20MHz, and 30MHz. Record
the results and verify that the offset is between -80mV and +80mV at all of
the frequencies.
SUBHARMONICS
This test measures the subharmonic content of the DS345's sinewave out-
put. This is residual carrier feedthrough from the DS345's frequency doubler.
The frequencies in this test are picked such that spurious frequencies from
the DDS process do not fall on the carrier position.
specification: <-50 dBc
1) Connect the DS345 to the RF spectrum analyzer. Set the DS345 to sine
wave, +23.98dBm (10Vpp), 0V offset.
2) Set the DS345 to to 102 kHz. Set the spectrum analyzer to 51 kHz center
frequency, 10 kHz span. The carrier amplitude at 51 kHz should be less than
-26.02 dBm. Record the result.