Giga-tronics Series 12000A, Руководство по эксплуатации

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Series 12000A Microwave Synthesizers
4-10 Publication 31231, Rev. J, October 2003
4.3.1.2 Additional Requirements (Series 125XXA/127XXA Only)
• DC Voltage Source 0-10 VDC, .5% Accuracy, 100 mA (Tektronix™ PS280 or Equivalent)
• Audio Oscillator, 10 Hz-200 kHz, 2 V
P-P
+/- .01 V into 50 ohm (Stanford Research™ DS-345 or
equivalent)
• HP™ 8902A Measuring Receiver
• Giga-tronics Series 12520A or 12720A Synthesizer
• Giga-tronics Mixer/Divider (P/N 002CA04900)
• Digital Voltmeter 3 ½ digits (Fluke™ 8920A or Equivalent)
4.3.2 Timebase Calibration
The Series 12000A uses an internal 10 MHz oven oscillator to provide a frequency reference for the
synthesizer and other associated circuits. The oscillator uses Electronic Frequency Control for its
adjustment. Before calibrating the frequency of the oscillator, the instrument must be left connected to
a power source for at least 24 hours. The oscillator runs when the instrument is in standby mode, so it is
not necessary to have the instrument turned on during the warm-up period.
To perform the calibration, connect the 5 MHz or 10 MHz source to the Reference Input and initiate
the calibration process from the service menu. The computer will determine the frequency of the
external source then lock the internal oscillator to that source. After a stable phase lock has been
achieved, the EFC voltage for the oscillator will be measured and stored. When the external source is
removed the computer will set the EFC voltage to the stored value to maintain the set point.
4.3.3 Output Amplitude Calibration
There are three types of calibration associated with the amplitude control system. The first determines
the relationship between the actual output power and the detector output voltage. Data is taken for
each of the internal detectors and at each of the various gain settings in the input amplifier. The data is
stored as coefficients to an equation, which describes the detector characteristic. The second set of data
determine the relationship of the modulator input voltage to the change in output power. As with the
detectors, data is developed for a set of coefficients used in a defining equation. The last calibration
produces a table of correction coefficients as the frequency is varied over the operating range of the
instrument
4.3.3.1 Power vs. Detector Voltage
For this calibration, the power sensor is connected from the power meter to the 12000A RF output, and
the power meter IEEE 488 control is connected to an IEEE equipped computer. The test program
supplied by Giga-tronics is now run. For each of the installed internal detectors (one is used for .01 to
2 GHz and another for 2 to 20 GHz) and for each gain range of the ALC input amplifier, the instrument
will step the power and determine the relationship between the actual RF power and the dc input to the
Analog-to-Digital Converter. This calibration is done at one frequency. The data taken develops a set of
coefficients which are used in an equation that defines the shape of the detector curve.
4.3.3.2 Modulator Control vs. Applied Voltage
This calibration is essentially the converse of the previous one. Here the intent is to determine the
relationship of the control voltage for the leveling modulator to the change in RF output power. A
separate set of coefficients is developed for each octave.