Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Zarrir on December 06, 2016, 09:20:57 pm

Title: Tube Rectifier Power Supply with No Load
Post by: Zarrir on December 06, 2016, 09:20:57 pm

Hi there Amptweakers!  How long can a high voltage tube rectifier power supply stay ON without a load? What happens if this mistake is commited?

Title: Re: Tube Rectifier Power Supply with No Load
Post by: PRR on December 06, 2016, 09:55:07 pm

If the caps are not sitting over rated voltage, forever.

A rough analogy: how long can I keep my water turned off while the water company maintains pressure? Pretty much forever.

Yes, if the supply makes 420V loaded and 470V no-load, and you used 450V caps, it may take hundreds of start-up surges to 465V and back to 420V loaded, but won't stand 470V no-load for very long before the cap blows up.

Title: Re: Tube Rectifier Power Supply with No Load
Post by: Zarrir on December 06, 2016, 10:05:11 pm

Thanks PRR, concise and spot-on.  I was concerned about the tubes lives.