opt's

[brian newman]

I'd like to build my first 6v6 amp and would like to use as many parts that I already have as possible.
I have a couple of opts that I have no info on.
Does anyone know or have info on how to test these to find out there specs.
Also if a given PT has higher Voltage than a tube can take,whats the simplest way to drop the voltage.Is this practical??

Thanks Brian

[stokes]

To check an output tranny's impedence you will need a signal generator and a multimeter.If you dont have a signal generator a variac will do.You have to apply a .5 vac across the secondary winding,then measure the volts at the primary,lets say you get 14 volts ac.double that number you get 28,this is your turns ratio,28 to 1.Next you square the 28 and get 784,multiply that by your speaker load,for instance 8 ohms will give you 6272.This is the primary impedence,in this case it would be good for a pair of 6V6's into an 8 ohm load.Your primary impedence will change with different speaker loads,so you may have to use a 16 ohm or 4 ohm speaker to get the 6000 to 7000 primary impedence you want to see for a pair of 6V6's.As for the watts an OT can handle you just gotta guess by the size of the tranny.To lower the volts from the PT you can add an extra cap and resistor between the rectifier and the cap your OT center tap is tied to.If you need to drop more volts than that you can put a zener diode, of the target volts you want to drop and I would suggest 50 watts to be safe,between the PT CT and ground.

[brian newman]

Thanks Stokes
Finally got that book on electronics I ordered.Time to bone up on the subject.
So much to learn so little time!!

Brian