Kenwood CS-1352 Instruction Manual

of A G - G N D - D C switch. However, the A Cposition may be used without affecting theresult except at very low frequency (below 5Hz).4. Adjust the vertical gain controls for a con-venient viewing height.5. Adjust the s w e e p time controls for one cycle ofsquare wave display on the screen.6. For a close-up view of portion of the squarewave, use the X 5 magnification.S Q U A R E W A V E G E N E R A T O RI N P U TA M P L I F I E RC I R C U I TB E I N G T E S T E DA D J U S T V E R T G A I N F O RC O N V E N I E N T V I E W I N G H E I G H TO U T P U TA D J U S T S W E E PS P E E D F O R 1C Y C L ED I S P L A YS L O P E +I N TF i g . 2 8 Equipment set-up for square w a v e testing of amplifiersAnalysing the Waveforms:The short rise time which occurs at the beginningof the half-cycle is created by the in-phase sum ofall the medium and high frequency sine w a v e com-ponents. T h e same holds true for the rapid drop atthe end of the half-cycle from maximum amplitudeto zero amplitude at the 1 8 0 ° or half-cycle point.Therefore, a theoretical reduction in amplitudealone of the high frequency components shouldproduce a rounding of the square corners at all fourpoints of one square wave cycle (see Fig. 2 9 ) .Distortion can be classified into the following threedistinct categories:Fig. 2 9 S q u a r e w a v e response with highfrequency loss1. The first is frequency distortion and refers tothe change in the amplitude of a component ofa complex waveform. In other words, the in-troduction in an amplifier circuit of reasonantnetworks or selective filters created by com-bination of reactive components will createpeaks or dips in an otherwise flat frequencyresponse curve.2. The second is non-linear distortion and refersto a change in waveshape produced byapplication of the waveshape to non-linearcomponents or elements such as vacuumtubes, an iron core transformer, and in an ex-treme case, a deliberate non-linear circuit sucha s a clipper network.3. The third is delay or phase distortion, which isdistortion produced by a shift in phasebetween one or more components of a com-plex waveform.In actual practice, a reduction in amplitude of asquare wave component (sinusoidal harmonic) isusually caused by a frequency-selective networkwhich includes capacity, inductance or both. Thepresence of the C or L introduces a difference inphase angle between components, creating phasedistortion or delay distortion. Therefore, in squarewave testing of practical circuitry, w e will usuallyfind that the distorted square wave includes a com-bination of amplitude and phase distortion clues.24