New output transformer speced as 450vdc max operating voltage

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Helmholtz
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Re: New output transformer speced as 450vdc max operating voltage

Post by Helmholtz »

Are you sure both windings are 6.3V?
As an original Deluxe uses a GZ34 rectifier requiring an isolated 5V heater winding, I'd have expected one 6.3V and one 5V winding.
Last edited by Helmholtz on Fri Jan 10, 2025 7:49 pm, edited 1 time in total.
sluckey
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Re: New output transformer speced as 450vdc max operating voltage

Post by sluckey »

pjd3 wrote: Fri Jan 10, 2025 4:29 pm The PT's I'm using for this stereo amp build each have both a 6.3vac/3A coil and a 6.3/5 @ 2A. Obviously, the 2A coil can be used for either signal tubes or rectifier tube heaters.
This sounds like a PT for Marshall 18W amp. The 6.3v @ 3A is meant to be used for all the tubes EXCEPT the rectifier. The 6.3/5 @ 2A is meant to be used only with the rectifier. You can use with a 6.3V rectifier such as EZ81 or you can use with a 5V rectifier such as 5Y3 or GZ34. You cannot use the 6.3V and 5V at the same time. It's one or the other.
Helmholtz
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Re: New output transformer speced as 450vdc max operating voltage

Post by Helmholtz »

A 5V heater winding is meant to float on B+.
sluckey
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Re: New output transformer speced as 450vdc max operating voltage

Post by sluckey »

Helmholtz wrote: Fri Jan 10, 2025 5:27 pm A 5V heater winding is meant to float on B+.
That's true, but only because for the directly heated 5V rectifier tubes the cathode is the filament. For indirectly heated 5v rectifier tubes the cathodes are usually internally connected to the filament. What was your point?

The winding being discussed is a 6.3V winding with a tap at 5V. It can be used for either tube type.

https://www.mojotone.com/transformers/B ... 18W-PT.pdf
pjd3
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Re: New output transformer speced as 450vdc max operating voltage

Post by pjd3 »

Heyo,

The 2A coil has both a 6.3V and a 5V tap to choose which one you need. My amp is going to be SS diode rectification. I have no use so for for the 5V tap (which I assume is to be used if you have a tube rectifier).

If left to my own discretion I would simply power all the heaters with the 6.3vac/3A coil. I just figured I'd find out if there was any utility in divying up the 2 coils to at least draw some current through both of those coils. I'm not a huge expert on the inner power transfers of energy inside a PT so, figured I'd inquire about it. My guess is that the PT wont care how I do it.

There was another PT I was going to buy but, it was mis-speced at 90mA for the HT I believe. The owner steered me to another new line of PT that had a little more juice to offer up on the HT coil.

Thanks,
PJD3
I’m only one person (most of the time)
sluckey
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Re: New output transformer speced as 450vdc max operating voltage

Post by sluckey »

If the 6.3v 3A winding will handle all the tubes then just use that winding and tuck the other winding out of the way. KEEP IT SIMPLE!
Helmholtz
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Re: New output transformer speced as 450vdc max operating voltage

Post by Helmholtz »

sluckey wrote: Fri Jan 10, 2025 5:48 pm The winding being discussed is a 6.3V winding with a tap at 5V. It can be used for either tube type.
Sorry, I missed the 5V tap and was confused.
lonote
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Re: New output transformer speced as 450vdc max operating voltage

Post by lonote »

I used the unneeded 5V feed on the last full build I did for an LED pilot light.
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