Model 8640B TM 9-4935-601-14-7&P
PERFORMANCE TESTS
4-34. AM SENSITIVITY AND ACCURACY TEST (Cont'd)
and a = VRF 2/VRF 1 (i.e., a = attenuation; for 20 dB it is 0.1)
therefore
V off = VDET 2 +50 mVdc
0.9
f. Reset step attenuator to 0 dB, Signal Generator as specified in step 1, and spectrum analyzer as specified
in step 3.
5. To calibrate the spectrum analyzer for the percent of AM measurement, use the analyzer's reference level
controls to set -282.8 mV + Voff at vertical output (as measured on the DVM). For example, if Voff is +50.0 mV,
then set -282.8 mV + (+50.0 mV) or -232.8 mV at vertical output. (Check that trace is peaked on analyzer
display.)
6. To measure modulation percent, set DVM to measure mVrms (ac only). The DVM should read 180 mVrms +
5%. (Check that trace is peaked on analyzer display.)
External Sensitivity Accuracy: 171.0 189.0 mVrms
7. To check indicated accuracy, set test oscillator's amplitude controls for a reading of 9 (90% AM) on the 0 10
scale of generator's panel meter. The DVM should read 180 mVrms +8%. (Check that trace is peaked on
analyzer display.)
165.6 194.4 mVrms
8. Set the test oscillator's amplitude controls for the panel meter readings shown below. The DVM should read as
specified. (After each reading, check that trace is peaked on analyzer display.)
Panel Meter
% AM Digital Voltmeter Reading
Reading (Set) Scale
70% 7 0 - 10 128.8 ______________151.2 mVrms
50% 5 0-10 92.0 ______________108.0 mVrms
30% either 3 0 - 10 55.2 ______________ 64.8 mVrms
or 3 0 - 3 54.6 ______________ 65.4 mVrms
20% 2 0 - 3 36.4 ______________ 43.6 mVrms
10% 1 0 - 3 18.2 _______________1.8 mVrms
NOTE
30% AM may be set on either the 0 - 10 scale or the 0 - 3 scale, depending upon
whether 30% is approached from above or below.
4-53
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
To Next Page
Loading...