In-Line Impedance Measurement Under Power

If the reading on the meter is decreased when the X dial is advanced from zero, the load is inductive and a null can be obtained. If the reading is increased when the X dial is advanced from zero, the load is capacitive and the L-C switch must be changed to the C position. After a minimum has been obtained on the meter, the gain control is further advanced and further adjustments are made on the R and X dials unitl a deep, sharp null is obtained. The R and readings are noted and the X reading is corrected for frequency, as described above. 

If either the R or X dial is advanced to its maximum value before a null is obtained it will be necessary to switch in one or both of the adder switches. When a null of obtained by the use of these switches, the values marked on the adder switches are added to the reading on the dials to obtain the load impedance. 

---