Unit 2(I) - WordPress.com

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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 =E 2 rms

/R heater

Vo

A ( V 1

V 2 )

A at v 1

  high balanced

 v 2 gain

 of d .

c amplifier condition v 1

V 2

KE

2 kV

O rms

2

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