Filament Overvoltage

[clyde]

I'm planning on using the 115v tap on a Hammond PT, needing the boost in voltage but am concerned about filament voltage being too high.  Lowering the 6.3v tap can be done with either diodes or resistors as I understand.  Any preferences and why?  However, how do I handle the 5v rectifier tap? 

[lkrasner]

I would be very surprised if the higher voltage caused any issue. Maybe tube life will be decreased a bit. If you want to be safe, just put a resistor in. It's simple and reliable.

Calculate your total filament current, then use ohms law to figure out what resistor you should use to drop it down to 6.3.

[kagliostro]

Ditto for the 5v winding


K

[clyde]

And the B+ on the 5v winding?

[sluckey]

And the B+ on the 5v winding?

Should not be affected.

[clyde]

Cool, thanks.

[clyde]

Good old RG, always on top of things.  It isn't exactly what I'm needing as I want the higher B+ running the PT on the 115v tap, just worried about the filaments running at 7.1v. 

[Willabe]

I'm planning on using the 115v tap on a Hammond PT, needing the boost in voltage but am concerned about filament voltage being too high.  Lowering the 6.3v tap can be done with either diodes or resistors as I understand.  Any preferences and why?

Here's the 1st post guys. ^

He needs the extra B+dcv. So a bucking transformer is out.


                 
                         Brad