simple heater question .....

[Minion]

Hi guys , here is a stupidly easy question for you ......

I"m running 6.3v AC heaters and the data sheet for the 12ax7 says that at 6.3v the heater draws 300ma Current ...... is that 300ma (150ma per triode) per tube or 300ma per triode (600ma per tube) .......

I need to know becasue my 6.3v tap is putting out 7.75v under a load (2 x 12ax7) and I need to calculate what resistor to use to drop it to 6.3v ....


thanx

 

[Eli Duttman]

Each section of the 'X7 draws 150 mA. of heater current. Connect the sections' heaters in series and you need 12.6 VAC/150 mA. Connect the sections' heaters in parallel and you need 6.3 VAC/300 mA.

 

[Minion]

Thank you very much ...... I"m connecting two 12ax7 tubes in paralell , so 2 tubes or 4 sections will draw 600ma total ..... Thanx a lot

 

[Poindexter]

Well stated, Eli.

P