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[QUOTE=bob91343;3050710]The main thing you save is filament power. A 5U4 wastes 15 Watts just to light it.
Not to be picayunish, but the filament wattage saved by replacing a 5U4 (or a 5Y3) with silicons is largely offset by the higher wattage that's now dissipated AS HEAT in the HV winding and added dropping resistor(s). This is due to silicon diodes' low forward drop compared to vacuum diodes.. plus the fact that the silicon diode is "full on" during is conduction period. Wattage that was formerly dissipated in heating the 5U4's plates now heats up the HV winding even more, and in some cases can cause the xfmr to run hotter than before the conversion.
It's a good idea to measure 'before-and-after' current draw from the wall when converting to silicons.
Last edited by old_coot88; 10-12-2012 at 07:32 PM.
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