Vectronics SWR-584C - Manual (Page 11)

SWR-584C Instruction Manual HF/VHF/220MHz SWR Analyzer
11
capacitive because the reactance exhibited by a capacitor tends to decrease as frequency
increases.
Standard vs. Measured Values: Even though a Standard Value may be stamped on the
case, a capacitor rarely measure that value at RF because of ambient temperature,
manufacturing tolerances, and differences in the test frequency. The sensitivity to frequency
occurs because stray inductance compounding inside the device and along the leads running
to the analyzer's calibration plane form a series-LC circuit. Normally, this condition causes a
capacitor's value (in pF) to increase with frequency, and it may even reach infinity if the circuit
becomes series-resonant (X=0).
4.5 Measure Inductance (uH): This function measures the reactance of an unknown inductor
in Ohms (X) at a given test frequency and computes inductance in uH. To measure
inductance:
[ ] Turn on the analyzer and allow it to boot to default mode (R&X).
[ ] Press Mode three times to access Inductance and wait for the working screen.
[ ] Adjust the Frequency switches and Tune control to the desired test frequency (MHz).
[ ] Using the shortest leads possible, connect the inductor to the Antenna jack.
Alternatively, you may use the same lead length used in the actual circuit so stray inductance
will be incorporated into the measurement.
[ ] Read Reactance (X
L
) in Ohms on top line, and read Inductance in uH on the lower line:
[ ] Also, read Reactance (X
L
) in Ohms on the analog Impedance meter:
Ohms
40 50 70 100 400
0 10 20
The measurement range for Reactance is 7-650 Ohms. Values falling outside that range will
prompt one of the following error messages:
Too low to measure (X<7) Parallel-resonant (X=0) Too high to measure (Z>650)
100.000 MHz
76
Inductance
in uH 100.000 MHz
L(Z)>650
100.000 MHz
L (X<7) X
L
100.000 MHz
L (X=0) X
L
100.000 MHz
L (Z>650) X
L