Giga-tronics 2500B Series Microwave Signal Generators
Performance Verification
Operation Manual, Part Number 34737, Rev C, June 30, 2011
Page 121
9.2.12
Frequency Modulation Accuracy - High Rate
This procedure tests the frequency modulation accuracy of the 2500B in wide mode.
9.2.12.1
Equipment and Materials
Microwave spectrum analyzer
Function generator
Cables and adapters for connecting the test setup
Datasheet 9 (Table 78 on page 122)
Table 77: Frequency Modulation Accuracy - High Rate
Frequency Modulation Accuracy - High 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: 830.055 kHz
Output: 2.00 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 of
the 2500B to the following:
FM State: Off
Sensitivity: 15 MHz/Volt
5.
Set the output of the 2500B to the first frequency in datasheet 9 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 = 18.0711 * Rate (Function Generator Frequency)
+5 % = 15.75 MHz, -5 % = 14.25 MHz
9.
Repeat steps 5 through 8 for the remaining frequency test points.
10.
After you have entered all of the test results onto Datasheet 9, compare the test results with the
following to verify compliance of the 2500B:
End of Procedure
RF ON
