question for the gurus: why GZ34 (or monst tube rectifiers) max smoothing cap 60uf?

[mikepukmel]

Hi All,.
I don't understand tube physics (yet!), anyone know why tube rectifiers have a fairly low max capacitor design value? E.g. GZ34 one sheet said max 60uf.
Thanks
Mike

[Enzo]

An uncharged cap looks like a short circuit to the rectifier until it has a charge on it. The larger the cap, the more current it takes to charge it. If you install too large a cap, it tries to draw too much current through the rectifier tube.

[mikepukmel]

Thanks Enzo!

[Enzo]

Yep, and I over simplified it a little, each half cycle of rectified current recharges whatever has leaked out or been used from the caps. The larger the cap, the higher the potential charging current while in use.