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Questions about tubes and gear that glows. FAQ

RE: That is the electrical equivalent to a 5R4

"Which has a 4uF first cap limit"

No it doesn't.

It has a max peak repetitive current rating (like all rectifier tubes) that can not be exceeded.

4uf, depending on the voltage, current and resistances involved, can cause the max peak repetitive current rating to be exceeded while in a different situation with different voltage, current and resistances a 50uf cap would be fine.

I have stated this truth about rectifier tubes and tried to explain about the input cap value given on the data sheets and what it means many times but no one seems to listen.

The data sheet linked below shows a input cap value of 20uf. The data sheet also shows the operating conditions that allows that value.

If you have different operating conditions then the max input cap value will be different.

Again, it's the max peak repetitive current rating that can not be exceeded.

If the voltage is less and/or the current is less and/or the series resistance is more then the uf value of the input cap can be higher without exceeding the max peak repetitive current rating of the tube.

There is no magic "max input cap value" associated with rectifier tubes.


Have Fun and Enjoy the Music
"Still Working the Problem"

Edits: 04/25/17 04/25/17

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