Giga-tronics 2500B Series Microwave Signal Generators
Performance Verification
Operation Manual, Part Number 34737, Rev C, June 30, 2011
Page 119
Table 75: Frequency Modulation Accuracy - Low Rate
Frequency Modulation Accuracy - Low Rate
Step
Action
1.
Allow the equipment to warm up for at least 30 minutes.
2.
Connect the equipment as shown in Figure 53 on page 118.
Connect the function generator to FM/φM IN on the rear of the 2500B
Connect the spectrum analyzer timebase output to EXT REF IN on the rear of the 2500B.
3.
Set the function generator to the following settings:
Waveform: Sine wave
Rate: 5 kHz
Output: 2 Vp-p into 50 Ω. This must be set as accurately as possible.
4.
Set the output level of the 2500B to 0 dBm, press
, and set the external FM settings to
the following:
FM State: Off
Sensitivity: 12.024 kHz/Volt
5.
Set the output of the 2500B to the first frequency in datasheet 8 and adjust the spectrum analyzer
frequency to match the test frequency. Adjust the reference level of the spectrum analyzer until the
peak on the top graticule of the display.
6.
Set the FM State to On.
7.
Adjust the rate of the function generator ± X kHz until the FM carrier is reduced at least 50 dB (Bessel
Null) from the un-modulated signal reference on the spectrum analyzer.
8.
Using the following formula, determine the FM Deviation error of the 2500B. Record the result in the
datasheet.
Measured deviation = 2.4048 * Rate (Function Generator Frequency)
+5 % = 12.625 kHz, -5 % = 11.423 kHz
9.
Repeat steps 5 through 8 for the remaining frequency test points.
10.
After you have entered all of the test results onto Datasheet 8, compare the test results with the
following to verify compliance of the 2500B:
End of Procedure
RF ON
