SFRA45 User Manual
10-1
10
Impedance Mode
The meter is used to measure the impedance of different
circuits and can range from 100mΩ to 100kΩ. Typically
used in power line carrier applications, this could be a line
trap or parallel L/C in a line tuner etc.
The signal generator must be turned on to read
impedance. Note: when LCR mode is selected it
automatically turns the signal generator on.
For impedance measurements, normally the low output of
the signal generator is fed into the ‘high Z’ input and the
circuit under test. Through the internal shunt, the
instrument measures the current drawn from the signal
generator while the input measures the voltage across the
circuit being tested. When sweeping across a band the
instrument can detect up to two impedance peaks and
markers can be set for both.
From the fundamental components of voltage, (a + jb),
and those of the current, (c + jd), the complex impedance
is given by:
z
=
v
/
i
= (a + jb) / (c + jd)
