Thank you Larry,
I don't know the math either, but I think you gave a much better explanation than I did. John, WA5BXO -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Larry Will Sent: Monday, March 13, 2006 12:25 PM To: Discussion of AM Radio; 'Discussion of AM Radio' Subject: RE: [AMRadio] Class AB and B audio XFMRS Hi all, As I dimly remember from Motors and Machines 1 and 2, THE TRANSFORMER IS A HIGHLY NON-LINEAR DEVICE. WE USE THESE SIMPLE FORMULAS for TR and ZR but in reality YOU NEED ADVANCED CALCULUS TO adequately explain BOTH THE Hysteresis and eddy current losses and distortions. The open circuit and short circuit tests can get that info out of a particular device, I haven't done these in years but it is a valuable tool for analyzing any transformer. You need power and the correct frequencies however. Its the hysteresis losses that result in the poor LF response. The secondary voltage lags the primary current (I think I remember that correctly) more and more as the frequency is decreased. The problem is especially acute at the polarity change, ie the zero crossing where the magnetic field must reverse instantly. The non linear effects generate a discontinuity in the waveform and the harmonic components and odd phases are the result. What is happening the primary power is converted to a magnetic flux which is then converted back to power in the secondary. Its the medium - the IRON that causes the problems. This cannot be analysed except by non-linear mathematics Messy at best. The DC current, if present polarizes the magnetic field making the effects worse. MacIntosh got around this with his patented transformer and circuit which greatly minimized the magnetic non-linearity, circuits which are still used in MacIntosh audio amps today. BTW audio analog tape recorders minimized this problem with the head by using a high frequency bias, say 22 kcs, to keep the flux constantly changing and allowing good LF response while making the recording. The HF signal is filtered out on playback either by the playback head or immediately before the first preamp. Larry W3LW Some folks on here surely can amplify this and correct my fuzzy memory if needed. The problem is the energy transfer medium - THE IRON.
