4v for rectifier tube
 

a silly question: what will happen if i use a 4v supply for a 5v specified rectifier like a 5y3 or 5u4g tube?

larry

You can probably get away with it, but only if you are drawing well under the maximum current for the tube.

Sheldon

4v
 

thanks.

If you under power the filament of a power diode, you will lose Isurge capability, and increase Vf. It's not a good idea, especially if your design is bumping against the max ratings.

It'd be better to get a proper filament xfmr for the type.

A small 5V 2A transformer (only 10VA) is worth it for a 5AR4/5Y3 type.

4v
 

thank you guys. i better ask my winder for a new transformer.

Re: 4v
 

Or possibly use a 4V rectifier tube... :D (Some rare German and English types, look on eBay)

Re: 4v
 

If you are not pushing the rectifier to its current limits, don't worry, try it. Your 4V winding may give you something a little higher than 4V, and virtually all tube are rated at least +/_ 10%, so 4.5V on the filament would be within normal rating anyway. You don't have to try your best tube - 5U4G's are cheap and readily available.

Sheldon

A pair of unloved 3V damper tubes with resistor in the heater would also work if you're concerned.

Cheers!

Better not to use it; 5u4g has excessive heater current draw (3A vs. 2A for e.g. gz32 and gz34) which will further decrease your voltage under load.

Simon