Giga-tronics 8003, Operation Manual

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Performance Test & Calibration
Manual 20791, Rev. C, June 2001 4-7
4.3.2 Instrument Plus Power Sensor Linearity
4.3.2.1 Test Description
Connect the test setup as shown in Figure 4-2. The linearity will be tested over the range +20 dBm to
-60 dBm (CW Mode) and +20 dBm to -50 dBm (Swept Mode). At low power levels, the linearity
measurement will include the uncertainty due to the zero set specification. The procedure should be
repeated for each sensor used with the 8003.
When measuring the linearity of a low VSWR (8031XA Series) or a high power sensor (8032XA
Series) sensor, the power output of the source as well as the directional coupler coupling factor, must be
increased from 10 dB to either 16 or 20 dB respectively (see Figure 4-2). The power coefficient of the
step attenuator will also have to be considered. The specification of power coefficient for the Weinschel
attenuator cited in the Equipment List is: <0.005 dB/(dB/W). The latter will affect the linearity of each
10 dB segment, and make it necessary to expand the overall linearity specification by this quantity.
In assembling the test setup shown in Figure 4-2, keep in mind that if testing is to be conducted with
Low VSWR or High Power sensors, the optional RF Amplifier must have frequency and bandwidth
parameters to match the sensor’s characteristics (see the Sensor Selection Guide in Appendix A, if
unsure of characteristics), and the Directional Coupler must be increased as stated above for the
particular series of sensors. All Standard (8030XA Series) and True RMS (8033XA Series) sensors are
tested with a 10 dB Directional Coupler and without the optional RF amplifier, and with a 10 dB
Directional Coupler.
Figure 4-2: Power Linearity Test Setup