Quote:
Originally Posted by old_tv_nut
...In the usual designs I worked on, the secondary was tuned to the third harmonic of the retrace. Some later ones were tuned to the fifth harmonic. The idea was to have the third harmonic in the secondary out of phase with the retrace pulse at the high voltage winding top, and have just the right amplitude so that the third harmonic tended to flatten the top of the transformed flyback pulse. This meant that the high voltage rectifier had a broader flatter voltage pulse input, making the high voltage output more stable with varying amounts of beam current. In other words, the impedance of the high voltage supply was reduced so that it was "stiffer" and there would be less variation with beam current, meaning less blooming. It is this improvement that you will lose if you wind a new secondary without redoing it by trial and error to get the tuning right.
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Interesting about the impedance-lowering effect. Just learnt something new.
I always assumed the HV 'tire' was sharply resonant somewhere around 70-80 khz (or kilocycles as we called it in those days). Would that be somewhat correct?