UTC M-1433 output transformer info - suitable for RCA Ba-2 build ?

[beatnik]

Hi everybody

I have found an UTC transformer M-1433

This is not to be found on UTC catalogs so I guess it's a custom made or military grade transformer

The specs written on the transformer says 25K primary impedance and 600 / 150 secondary , plus a tertiary winding for feedback

I was wondering if anybody has more data about this transformer, in particular I am interested if the transformer is meant to handle unbalanced dc current

I would like to figure out if this transformer can be used for a RCA Ba-2 type build

Thanks in advance

 

[emrr]

That should also have a General Electric # on it.  It's for their version of the Collins 356A.  You don't want to waste a feedback winding on a BA-2, and it likely does not have the inductance for one either since the feedback winding is fixing response. 

 

[beatnik]

Thanks for the info

 

[CJ]

it will handle DC , can't vouch for how much, plate current from a 5879 is what?

edit: this might be the wrong schemo, pin numbers different,  :

 

[rackmonkey]

I think you were bidding against me for that.  As EMRR says, that’s for the GE variant of a common mic pre design that used two 5879s (later, two EF86 in the Collins version) with a tertiary winding for negative feedback.  Langevin’s version was model 5116 (not 5116B) and GE had the BA-1F and BA-1-H (not sure of the differences, if any, between the two).  Nominal OT primary impedance was lower for the non-GE versions (16.5k for Langevin and around that for Collins IIRC).

Those transformers are hard to find and no one makes a modern copy.  Use it for a build of one of the above or sell/trade for something that’s better for your BA-2x project. My $.02 anyway.

I did manage to get one of these from the guy selling them on eBay. I’d be happy to donate it to CJ for thorough dissection and analysis so we’d have some data for repros. 

CJ, let me know if you’re interested.

BT

 

[beatnik]

I ended up scoring a utc a-25 that should be suitable for a ba-2 build

If you are interested there is another m-1433 on reverb, for a good price

https://reverb.com/item/3299694-utc-m-1433-transformer

 

[rackmonkey]

Cool. Thanks. Now I have a pair.

But offer still stands if CJ needs another victim for drawing and quartering.

BT

 

[CJ]

come on down!