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robert casey robert casey is offline
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Default Damper diodes as rectifiers

Maaark wrote:

I've seen people use dampers as rectifier before, and I like the
premise.. but something confuses me.


In the datasheets for 6AU4, 6AX4, etc, they state that "use of this tube
as a power rectifier is not recommended".

Why is it not recommended? I don't see any flaws.


Not sure either, but be sure to not exceed the peak current rating. In
rectifier service, such a tube will see a big peak of current as it tops
off the B+ filter cap. Just like regular rectifier tubes. But maybe
those can take more abuse (a 5U4 is directly heated, vs a damper which
is indirectly heated). Choke input filters should help with this here.

A nice feature of most damper diodes is the high voltage ratings for
heater-cathode. Which means you should be able to run the heater off a
grounded heater supply. Also makes for slow B+ turn on.

A downside with damper diodes is that virtually all of them have only
one diode inside, so you'd need a pair of damper diode tubes to replace
say a 5U4 rectifier.