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-   -   4v for rectifier tube (http://www.diyaudio.com/forums/tubes-valves/123162-4v-rectifier-tube.html)

camotecue 16th May 2008 02:11 PM

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

Sheldon 16th May 2008 02:27 PM

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

Sheldon

camotecue 16th May 2008 02:47 PM

4v
 
thanks.

Miles Prower 16th May 2008 10:46 PM

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.

sorenj07 16th May 2008 11:07 PM

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

camotecue 19th May 2008 02:38 PM

4v
 
thank you guys. i better ask my winder for a new transformer.

kevinkr 19th May 2008 02:51 PM

Re: 4v
 
Quote:

Originally posted by camotecue
thank you guys. i better ask my winder for a new transformer.
Or possibly use a 4V rectifier tube... :D (Some rare German and English types, look on eBay)

Sheldon 19th May 2008 03:08 PM

Re: 4v
 
Quote:

Originally posted by camotecue
thank you guys. i better ask my winder for a new transformer.
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

Geek 19th May 2008 07:22 PM

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

Cheers!

Klimon 20th May 2008 08:49 PM

Quote:

You don't have to try your best tube - 5U4G's are cheap and readily available.
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


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