SABA: Selenium rectifier

When I rebuild bridge rectifiers for German radios of this vintage, I use four 1N4007 diodes or a similar silicon bridge rectifier with four 0,0047 mfd snubbing capacitors, and one 100 ohm @ 10 watt power resistor. 

Would this be the same case for this radio too?  I observed on the late Paul Pinyot's web site that he did not use a voltage dropping resistor nor did he use snubbing capacitors

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This radio has a mainstransformer, I think you don't need a series resistor.

Snubbing caps are  advisable to prevent possible interferences up to FM freq.

rgds R.D.

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Sorry, but the internal resistance of the power transformer alone is not sufficient. The selenum rectifier has also an internal resistance, and if it is replaced by a silicon diode bridge, the resulting internal resistance is much lower. Therefore the voltage then is higher. That means, an additional series resistor will be necessary if a selenum rectifier is replaced by a silicon rectifier bridge. 

The value of this additional resistor is complicated to be calculated, because the result depends from the current flow angle. The easiest way therefore is to find the correct resistance value by experiment.

For additional information see a thread from 2005 on this topic.

Regards,

Dietmar

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