Stanford Research Systems DS345, Manual

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Calibration
6-3
NECESSARY EQUIPMENT
The following equipment is necessary to complete the adjustments and cali-
brations. The suggested equipment or its equivalent may be used.
Instrument Critical Specifications Recommended Model
Analog Oscilloscope 350 MHz Bandwidth Tektronix 2465
Time Interval Counter Frequency Range: 20 MHz min. SRS SR620
Time Interval Accuracy: 1ns max
FFT Spectrum Analyzer Frequency Range: DC to 100 kHz SRS SR760
Amplitude Accuracy: ±0.2 dB
Distortion: < 75 dB below reference
RF Spectrum Analyzer Frequency Range: 1 kHz to 100 MHz Anritsu MS2601/ HP4195A
Amplitude: ±0.5 dB
Distortion and Spurious: < -70 dB
DC/AC Voltmeter 51/2 Digit DC accuracy Fluke 8840A
True RMS AC to 100 kHz
Thermal Converter Input Impedance: 50
Ω
Ballantine 1395A-3-09
Input Voltage: 3 Vrms
Frequency: DC to 30 MHz
Accuracy: ±0.05dB
10 MHz Frequency Standard Frequency: 10 MHz ± .001 ppm SRS FS700
Phase Noise: < -130 dBc @ 100Hz
50
Ω
Terminator 50
Ω
± 0.2 %, 1 Watt HP 11048C
ADJUSTMENTS
The following adjustments set the values of all of the variable components in
the DS345. After an adjustment has been made the associated calibrations
must
be made. All adjustments must be complete before calibration is start-
ed. First, remove the DS345's top cover by removing the four retaining
screws. On units with an optional oscillator remove the mounting screw half
way back on the left side of the chassis. Next, remove the two left hand
screws securing the top circuit board. This board will hinge open (the option-
al oscillator hinges with the circuit board). Set the "cal enable" switch
(SW300 switch 2) to ON.
NOTE: The chassis ground and circuit ground float relative to each other.
For voltage measurements use the FUNCTION output BNC shield as a
ground reference.
Clock Adjustment
This adjustment sets the DS345's internal 40 MHz oscillator. Instructions for
both standard and optional oscillators are given below. The oscillator calibra-
tion should be done after this adjustment.
1) Connect the DS345's 10 MHz output to the frequency counter input. The
counter should use the frequency standard for its timebase. Be sure that the