Filiment transformer insulation

[N2IXK]

Originally Posted by jr_tech

I just measured the capacitance of a small 6.3 volt 2000 volt isolation transformer and found about 150 to 200 uuf between the 6.3 V winding and the primary and the core combined...
I would think that adding this extra capacitance to ground to the video output, which normally has to drive a much smaller capacitance, would reduce the frequency response, causing lack of sharpness of the display.

jr

Good point.

Perhaps add a couple inductors in series with the secondary legs to block the high frequency content from being shunted to ground through the winding capacitance?

[old_coot88]

Originally Posted by N2IXK

Good point.

Perhaps add a couple inductors in series with the secondary legs to block the high frequency content from being shunted to ground through the winding capacitance?

Or, put inductors in the primary legs and float (unground) the xfmr. frame. That would allow using higher value inductors without dropping the 6.3V too much. Just a thot.