Did I get the wrong power transformer?

[Tapsnap]

I got this power transformer from Edcor. I was mainly focused on the secondary voltage of 325v and didn’t give too much thought to the filament voltage. I assumed that I could twist together the two brown wires and use the center tap as the return. Now I’m not sure. Can I use the filament voltages to get 6.3 v or should I be looking at getting a different PT?

[Raybob]

 Center tap to ground. Brown leads = 6.3vac

[Tapsnap]

OK, just to be clear, you mean twist the two brown wires together and solder them to one side of the lamp fixture and the white and brown wire to the other side of the lamp fixture and then ground the two lamp lugs through a couple of 100 ohm resistors. Then I can connect the tube filaments to these lugs? Is that how I should wire this?

[2deaf]

Listen kid, never EVER connect two ends of a continuous winding together.

[vampwizzard]

OK, just to be clear, you mean twist the two brown wires together and solder them to one side of the lamp fixture and the white and brown wire to the other side of the lamp fixture and then ground the two lamp lugs through a couple of 100 ohm resistors. Then I can connect the tube filaments to these lugs? Is that how I should wire this?

Each brown wire needs to remain separate. Ground the brown and white wire. Attach one brown wire to one leg of the lamp. Attach the other to the other leg of the lamp. Then wire/attach to the rest of your heaters.

[tubeswell]

3.15 + 3.15 = 6.3 across the winding, which is what you want. Don’t connect the ends together (or the winding will be shorted).


The Center Tap gets referenced to ground, or to an elevated DC reference point if you want elevated heaters. When one end of the winding is at +3.15, the other end will be at -3.15 (so you will have 6.3 across the winding, which is what you want)

[Tapsnap]

I don’t get it. Surely the each cycle delivers only 3.15 volts to each filament, not 6.3.

[vampwizzard]

I don’t get it. Surely the each cycle delivers only 3.15 volts to each filament, not 6.3.

Each brown wire to the white and brown wire is 3 volts. when you go brown to brown with the white and brown wire grounded, you get 6.3 volts.

[Tapsnap]

Ok, I get it now. Thanks for being clear Vampwizzard.

[tubeswell]

You have to think of the absolute value between the integer numbers: there is 6.3 absolute numbers between the integer -3.15 and the integer +3.15

[Tapsnap]

Thanks for sorting that out for me. Now I have another quick question. How close can a power tube be to a Rectifier tube without causing any noticeable interference? I know the preamp tube must be kept well away from the power supply but I haven’t heard too much about the power tube being affected by it. Is this an issue?

[sluckey]

Interference is not an issue. However, heat is. I like to leave some "breathing room" between tubes for heat dissipation. I've seen some modules with power tubes and rectifiers packed so tight you could not get your fingers between them. Had to use a tube puller to change tubes. There was a forced air ventilation system.

The big tubes in this pic are mounted on 1-3/4" centers. Little tubes are 1-1/4" centers. This is the closest spacing I've used.

[Tapsnap]

OK thanks. That’s good to know.

[2deaf]

You have to think of the absolute value between the integer numbers: there is 6.3 absolute numbers between the integer -3.15 and the integer +3.15

Uuummmm.....What?

[sluckey]

You have to think of the absolute value between the integer numbers: there is 6.3 absolute numbers between the integer -3.15 and the integer +3.15

I know what you mean but that's a terrible analogy. For one, an integer is a whole number. No fractions or decimals allowed. For two, well I got no two! But one is enough.   

[1blueheron]

I tried to count it on my fingers like they taught us in kindergarten.  Now I am missing 3.15 fingers....

[tubeswell]

You have to think of the absolute value between the integer numbers: there is 6.3 absolute numbers between the integer -3.15 and the integer +3.15

I know what you mean but that's a terrible analogy. For one, an integer is a whole number. No fractions or decimals allowed. For two, well I got no two! But one is enough.   

Okay. I should’ve said 3 instead of 3.15 and 6 instead of 6.3 - Point taken. (Actually - there’s your two points) 🙃

[Tapsnap]

Man, tough crowd.

[shooter]

stick around we do quadratic equations at 5 

[tubeswell]

Yup This is how the west was won

[mresistor]

Man, tough crowd.

Only if you're level 1..       

[mresistor]

Yup This is how the west was won

Question..   is The West  applicable to Australia??    ( I guess if'n you're in Perth or Amboy )   

[shooter]

Yup This is how the west was won

   I've spent some quality time in the west, I don't think they got that memo, especially the rattle'rs, scorpions, bikers.......