6JU8A Spec confusion

[mashaffer]

I am not sure I understand the current specifications on the 6JU8A quad diode. The Data Sheet says "Steady State Peak current" = 54mA and DC Output Current" = 9mA. Now to me steady state peak is an oxymoron. If it is steady state then there is no peak and it should mean the same thing as DC output current.

So the only thing I can figure is that the peak current of a steady state sine wave can be up to 54mA instantaneous current and the filtered DC output from the filtering network can be a maximum of 9mA. Is that the correct interpretation?

mike

[anatech]

Hi Mike,
My guess would be close to yours.

Peak capacitor charging current is much larger than the peak value of an RMS sine wave figure. I suspect that they are referring to the peak charging current due to the way a capacitor is charged through a rectifier (this tube). The 9mA figure would be the steady state DC current you could draw from this tube as an absolute maximum.

How is that for an explanation?


-Chris

[Eli Duttman]

Mike,

If you want to bridge rectify a low current and modest voltage B+ rail, you would (IMO) be better off to employ a hybrid bridge made from 2X UF4007s and a 6AL5. The hybrid sounds every bit as good as the full vacuum bridge, while avoiding the unpleasant doubled forward voltage drop.

[anatech]

Hi Eli,
I don't think he is rectifying for a supply. Could be wrong though.

BTW, I have had very good results by adding series resistance to a rectifiers. I use normal recovery types as there is less noise. I have tried the UF4007 types and now I simply use 1N4007s.

-Chris

[mashaffer]

Not building anything with it right now. I am just going through the data sheets for the batch of tubes I just acquired and wanted to be sure I understood the operating limits. A bridge is just the first possible application to come to mind with a IDH quad diode. Voltage drop is only 10V per diode. Other applications my come to mind later and I have enough projects for a few months already anyway.

I appreciate the guidance.

mike

[pmillett]

Originally posted by mashaffer
Is that the correct interpretation?mike

In a word, yes.

Some data sheets call this "Maximum repetitive peak current", which makes a little more sense.

Some datasheets also list another peak current, which is a "surge" peak current, non-repetitive.

Pete

[mashaffer]

Hmm... a passing glance at Steve Bench's site reminded me of another potential use of dampers. Cathode bias. I know LEDs are cheaper but there is a certain cool factor here.

mike