Transcript Unit 2(I) - WordPress.com

Vector impedance meter
Can be used to measure magnitude
and phase angle of impedance.
At low frequency there is no change,
but to study about the component need to
be analyze with wide frequency. Covers
400 Khz to 110 Mhz.
Vector impedance meter
Constant current mode- lower range
(X1, X10, X100)
- unknown component connected across the
input of the differential amplifier. Current
depends on range of impedance switch.
- Transresistance amplifier converts current
through into voltage. (Op-Amp)
Constant voltage mode – (1k, X10K, 100K, 1M)
schmitt trigger – positive spike - binary phase
detector (Bistable multivibrator, differential amp,
integ capacitor) – constant current channel sets the
multivibrator, constant voltage channel resets the
multivibrator.
The set and reset outputs are applied to the
differential amp, which applies the difference
voltage to an integrating capacitor. The capacitor
voltage is directly proportional to the zero crossing
interval. Which gives the phase difference between
voltage and current waveforms.
Vector Voltmeter
• Amp gain and phase shift
• Complex insertion loss
• Filter transfer function.
• Two-port network parameters
Major parts
Two RF to IF converters
Automatic phase control section
Phase meter circuit
Voltmeter circuit
signals of the two RF signals of the same
fundamental frequency to two IF signals with
20 KHz fundamental frequencies.
These signals are having same amplitude
and phase of Original RF waveform.
Fundamental components are filtered from the
IF signals , measured by voltmeter, and a
phase meter.
RF to IF converters, Automatic phase control
section produce 20 Khz
Sampling Oscilloscope
TRUE RMS METER
For thermocouple Power =E2rms/R heater
Vo  A(V 1  V 2 )
A  high gain of d .c amplifier
at balancedcondition
v1  v 2
v1  KE 2rms
V 2  kVO 2