[AMRadio] Replacing 866A's with SS


JAMES HANLON knjhanlon at msn.com
Tue Nov 3 10:27:48 EST 2009


I would not be concerned about "higher voltage" problems when replacing 866A's or any other mercury vapor rectifiers with solid state rectifiers.  The forward drop across mercury vapor rectifiers is about 11 volts.  The forward drop across a single silicon diode is about 0.7 volts, and most replacement rectifiers use several silicon diodes in series to achieve the required reverse voltage breakdown capability, so the forward drop across a replacement solid state unit would be several times 0.7 volts.  The difference in forward drop between mercury vapor rectifiers and the solid state replacements is negligible.  So there will not be a "higher voltage" problem.

The same is not true if you are replacing a high vacuum rectifier.  They have considerably higher forward drop, upwards of 100 volts in some cases.  

Jim Hanlon, W8KGI


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