Performance Tests
Performance Test 3
3-19
Note
Use a common mode choke to obtain satisfactory noise performance
and accurate readings. Insert the common mode choke in series
between the feedthrough termination and the AC Measurement
Standard input, with the ground applied at the choke input. Keep the
ground connection as short as possible and set the AC
Measurement Standard to Internal Guard. A common mode choke of
250 µH is usually effective. A suitable choke is 6 turns of small-
diameter coaxial cable through a TDK toroid, manufacturer’s part no.
H5C2-T28-13-16 (available as Fluke part no. 474908) Refer to the
5970A Operator Manual for additional explanation.
Note
Measurements made on the 5790A 2.2 mV range (at levels below -
40 dBm) require correction for the 2.2 mV range linearity error.
hpn221.eps
Figure 3-5. Equipment Connections - 50 Leveling Head, Low Frequency Level Accuracy Test
Points (96040A and 96720A)
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