Tube Audio Transformers

[Duke58]

I have these three Stancor transformers in boxes marked:

Audio Transformer A-3321
From 1 or 2 6A6, 53's or 79's
To 3000 Ohms to carry .125 A.D.C.

Audio Transformer A-4406 P. P. Driver
From 2-45's or 2A3's
To 2-210's or 801's

Audio Transformer A-4405
P.P. Driver
From 1-2A5 or 42
Top 2-2A5's or 42's Class "B"

Are these power transformers or output transformers?

The instruction sheet says Primary connections, Plate-brown, C.T.- Red, Plate-Blue. Secondary Connections, 3000 ohms- Green and Black



Thanks for any help.

 

[Osvaldo de Banfield]

Effectively they're output transformers. The making says their characteristics.

 

[Duke58]

I didn't understand why it says the "from" and "to?"

 

[Tom Bavis]

They're interstage transformers, "driver" indicating that they feed a power stage, usually a class B or AB2 stage that requires some driving power. The first one appears to be a low-power modulation transformer - a push-pull audio stage would modulate the DC that powers an RF amplifier stage. They are different from audio output transformers in that the secondary carries DC current.

 

[Duke58]

Do you know of any schematics that would show interstage transformers in a circuit. Seems like they are power transformers? What would be the benefit or reason to use them?

Thanks!

 

[DougL]

Here is a page that discusses it:

The Amity, Raven, and Aurora

HTH

 

[Duke58]

Thank you all!

 

[disco]

Do you know of any schematics that would show interstage transformers in a circuit. Seems like they are power transformers? What would be the benefit or reason to use them?

Thanks!

It's not a complete schematic but it has the principle to look for. The purpose of your interstage transformer can be two fold: to split the audio signal into two opposed phases, or to deliver a beefed up audio signal at the final tubes.