Help me to identify a transformer.

[Bo-Lennart]

Hi all out there.
I found a transformer in my basement. I don't know if its a audio-output transformer or just a power transformer.
On top it's stamped "GALVIN MANUFACTURING CORPORATION",
and a model #: "25B31296-E" and a serial# ( ???? ) "138226"
At bottom there is 8 solder lugs, stamped: "1 to 8".
And at one side is 8 screw connector, labeled as "3A 12 11 2B 2A 10 1A 9".

To me it looks more like a tube output transformator, more than a power transformer.
It seems to be from the 1940 or somewhere around there.

Anyone know what it is, and have some kind of "schematic" of the transformer.

Many thanks in advance

Bo-Lennart Karlsson
Falun, SWEDEN

[Bo-Lennart]

[peterw...@gmail.com]

Galvin Manufacturing is the company that produced Motorola products out of Chicago, Illinois, USA. It is easy enough to trace it out using a small AC power-supply and a good True RMS VOM.

https://www.radioremembered.org/xfmr.htm takes you to the RMA (Radio Manufacturers' Association) Transformer color-code for power transformers. Motorola, being a founding member of the RMA would typically follow these codes, but for their military stuff that followed a different code, sometimes.

Audio Output Transformers usually have Green-Black-Green (and mixes) on the secondary side, and Blue-Red-Blue (and mixes) on the primary side.

Note that transformers often have multiple taps on the same winding. So:
a) Using your Ohms setting isolate the various windings from each other. A single winding will show continuity, but with variations in resistance from one tap to the next.
b) Isolate the windings from the lowest total resistance to the most total resistance - this is trickier than it seems as you want to include all taps, but measure the complete winding, not an internal tap. Even more so, if, for instance, you have a 5V winding off a 120 V primary - it will have a lower resistance than the primary winding - more on this later. Bundle each winding and all the taps together so as not to mix them up.
c) Starting with the lowest-resistance winding, apply some reasonable, but low, AC voltage -say about 20 VAC or so.
d) Measure voltages on the other windings. By experimentation, you should be able to discern the purpose of the transformer, the primary winding and any taps, and the secondary windings as well.

As an example: A typical audio power for tube equipment here in the US would get 120 VAC on the primary side, have a B+ winding that might give something between 325 and 450 VAC, one or two 6.3 V filament windings and, perhaps a 5 V filament winding. That would be as many as five total windings. Some few even have dual primary windings to accommodate multiple input voltages. So, it is complicated.

An audio transformer may have multiple taps, but the turns ratio between the primary and the full secondary will be fixed, and there will be only two windings in total.

Take your time - it is almost entirely unlikely that you will be able to trace *that* transformer by its part number.

Hope that helps.

Peter Wieck
Melrose Park, PA

[Fred Smith]

Audio output transformers generally don't interleave the "E" and
"I" laminations, and may have an obvious bit of waxy paper between
the block of E and I laminations. Power transformers almost
invariably do interleave the laminations (I've never seen one that
didn't).

[Phil Allison]

Fred Smith wrote:

----------------------

>
> Audio output transformers generally don't interleave the "E" and
> "I" laminations, and may have an obvious bit of waxy paper between
> the block of E and I laminations.
>

** Small transformers intended for "single ended" operation are like that - the rest are like power transformers.

The OP is being a real PITA by NOT supplying any info on how big his unit is or any of the winding resistances.

A pic would be revealing too.



.... Phil

[amdx]

Well Fred, if you are correct in your assertions, you will be Fred, if
Phil gives us his wisdom and it doesn't agree, we will find your aliases.
Mikek

[Phil Allison]

amdx wrote:

------------

> Fred Smith wrote:
>
> >
> > Audio output transformers generally don't interleave the "E" and
> > "I" laminations, and may have an obvious bit of waxy paper between
> > the block of E and I laminations. Power transformers almost
> > invariably do interleave the laminations (I've never seen one that
> > didn't).
> >
>
> Well Fred, if you are correct in your assertions, you will be Fred, if
> Phil gives us his wisdom and it doesn't agree, we will find your aliases.
> Mikek

---------------------------

FYI to all:

The Mikek troll knows more about "Aliens" than aliases.

Talks to them all the time, on long range AM radio.



..... Phil

[Michael Terrell]

On Friday, September 27, 2019 at 1:48:15 PM UTC-4, Bo-Lennart wrote:

25B31296-E is typical of Motorola part numbering.

It crosses to a NSN part which is a 120VAC 60Hz input power transformer:

https://nationalstocknumber.org/nsn/5950-00-648-0400

NSN are inventory numbers for items bought by the government.

[Dave M]

Galvin Manufacturing was the original radio manufacturing company that
eventually became Motorola. They started making consumer radios, and then
invented a record player that could be installed in an automobile. Thus,
came the name MOTOROLA, from MOTOR cars, and the old victROLA record player
(from RCA).
The 25B31296 part number identifies as a Motorola transformer, having the
following characteristics from the US military stock system:

5950-00-648-0404 Features
MRC Parameter Characteristics
ABKQ Center to Center Distance Between Mounting Facilities Parallel to
Length 2.625 inches nominal single mounting facility single center group
ABKR Center to Center Distance Between Mounting Facilities Parallel to
Width 2.375 inches nominal single mounting facility single center group
ABTB Mounting Hole Diameter 0.125 inches nominal single group
ACZB Frequency Rating 60.0 hertz nominal single component
ACZC Input-Output Phase Relationship Three phase to three phase single
component
ADAQ Body Length 3.875 inches nominal
ADAT Body Width 3.875 inches nominal
ADAU Body Height 3.500 inches nominal
AKNA Inclosure Type Hermetically sealed
AKPV Mounting Facility Quantity 4 single group
AXGY Mounting Method Flange single group and unthreaded hole single
group
BPLC Winding Function and Quantity 1 primary single component and 2
secondary single component
CWJS Winding Operating Voltage 145.00 ac volts nominal single
component 1ST secondary
CWJS Winding Operating Voltage 12.00 ac volts nominal single component
single primary
CWJS Winding Operating Voltage 5.80 ac volts nominal single component
2ND secondary
TTQY Terminal Type and Quantity 8 threaded stud and 7 tab, solder lug


No indication of the equipment it was used in, but more than likely a piece
of military equipment. Since the primary is specified as 12VAC, and
secondaries as 145V and 5.8V, it is likely to be a power transformer from a
vibrator power supply used in a military radio of some sort. Don't know how
the 3-phase spec works into it... could just be how the vibrator side of the
transformer was described.

Cheers,
Dave M

[amdx]

Any chance I saved him from some abuse? :-)
Can we call him Fred the PITA?
And, I don't talk to them, I just here the voices!
Mikek

[Cursitor Doom]

On Sat, 28 Sep 2019 09:03:41 -0500, Dave M wrote:

> Galvin Manufacturing was the original radio manufacturing company that
> eventually became Motorola. They started making consumer radios, and
> then invented a record player that could be installed in an automobile.

By God that must have taken some doing.



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[Phil Allison]

Cursitor Doom wrote:

-----------------------

>
> > Galvin Manufacturing was the original radio manufacturing company that
> > eventually became Motorola. They started making consumer radios, and
> > then invented a record player that could be installed in an automobile.
>
> By God that must have taken some doing.
>

** I've seen a portabe 45rpm player where the disk slid into a slot like bread in a toaster. The arm was held against the vinyl surface by spring pressure.

Crystal PU, of course, with no vertical compliance - a real "groove straightener".


.... Phil

[tabb...@gmail.com]

On Sunday, 29 September 2019 12:19:10 UTC+1, Cursitor Doom wrote:
> On Sat, 28 Sep 2019 09:03:41 -0500, Dave M wrote:
>
> > Galvin Manufacturing was the original radio manufacturing company that
> > eventually became Motorola. They started making consumer radios, and
> > then invented a record player that could be installed in an automobile.
>
> By God that must have taken some doing.

Cars had soft suspension & poor handling in the 50s, the ideal combination. Add a high tracking force xtal pickup and it ain't that hard. But they still skipped here & there.


NT

[Bo-Lennart]

Den fredag 27 september 2019 kl. 19:48:15 UTC+2 skrev Bo-Lennart:

[Bo-Lennart]

Den fredag 27 september 2019 kl. 19:48:15 UTC+2 skrev Bo-Lennart:

Thank You all for the reply.
I understand that there would be easier if I could present a picture of the transfprmer. I have pics, but I don't know how to present them here in this group.
I did some measuring with my L-meter, so I now know where the coils are.
I'm pretty new to this group. Please tell me if I can present a picture right here in these group. Or can I present a link to eg. One Drive or DropBox or similar....

Bo-Lennart Karlsson
Falun, Sweden

[tabb...@gmail.com]

The newsgroup is text only. You can put pics in imgbb.com, flickr, any free pic hosting site.


NT

[Cursitor Doom]

On Mon, 30 Sep 2019 01:33:31 -0700, Bo-Lennart wrote:

> I'm pretty new to this group.

Welcome aboard, friend! Unfortunately we have a few nutters here but take
my advice and just ignore them. ;-)

[tabb...@gmail.com]

On Monday, 30 September 2019 16:51:00 UTC+1, Cursitor Doom wrote:
> On Mon, 30 Sep 2019 01:33:31 -0700, Bo-Lennart wrote:
>
> > I'm pretty new to this group.
>
> Welcome aboard, friend! Unfortunately we have a few nutters here but take
> my advice and just ignore them. ;-)

Everyone needs an ignore list or killfile.

[Bo-Lennart]

Den fredag 27 september 2019 kl. 19:48:15 UTC+2 skrev Bo-Lennart:

I have uploaded som picture of the trafo. And I made a schematic of the
transformer.
Here is the links:

https://i.ibb.co/Jx3RtLR/20190929-155553.jpg
https://i.ibb.co/mh0k6rB/20190929-155912.jpg
https://i.ibb.co/z4PV2JZ/20191001-164147-001.jpg
https://i.ibb.co/QYVPqwR/20191001-164228.jpg
https://i.ibb.co/NKDynrF/20191001-164522.jpg
https://i.ibb.co/0Qq2xf0/20191001-164553.jpg
https://i.ibb.co/c2Rtcqw/20191001-164606.jpg

Well, I'm an old man (turned 70 early this yr), and I started my electronic profession very young. At that time the car radio had VIBRATOR to make 12V (or 6V) transformable.
And I start to think that it's a such transformer.
The screw-terminal could be switchable betveen 12 and 6 Volts use ?????.
How about that? Anyone have a better suggestions?

Best regards
Bo-Lennart Karlsson
Falun, SWEDEN

[Arie de Muynck]

> The screw-terminal could be switchable between 12 and 6 Volts use ?????.

> How about that? Anyone have a better suggestions?
>
> Best regards
> Bo-Lennart Karlsson
> Falun, SWEDEN
>

Hi,

Never knew Motorola started as Galvin Mfg Corp:
<https://en.wikipedia.org/wiki/Motorola>.
That tranny could be a real museum piece!

Could you double check the inductance between 7-8?
The combination of much higher inductance and still a low DC resistance
looks suspicious. Was it not 3.08 mH? Then it could be the separate
filament output for an HV rectifier tube.

The HV output for a vibrator transformer would have high resistance
(like 4-5-6) but a much higher inductance than the input windings, and
it isn't. Also suspicious.

Some 50 years ago I've repaired an old 12V (or 6V?) input tube
car-radio, and it had a vibrator inverter. However, the transformer was
much less complicated: just two primary and two secondary windings.
There was no rectifier tube, the vibrator also rectified the HV. The
tube filaments were directly run on the incoming 12Vdc.

Arie

[Phil Allison]

Bo-Lennart wrote:

----------------

>
> > To me it looks more like a tube output transformator, more
> > than a power transformer.
> >
>
>

> I have uploaded som picture of the trafo. And I made a
> schematic of the
> transformer.

> Here is the links:

https://i.ibb.co/NKDynrF/20191001-164522.jpg

------------------------------------------

** I will ignore some of your L figures (it's very difficult to measure inductances of the windings on a non-gaped iron transformer, cos they are large an non linear. )

The diagram shows *very* typical R vales for a push-pull audio output tranny of about 60 to 100 watts rating - ie 65 and 59 ohms for the CT primary and 0.66 ohms for an 8 ohm secondary.

The other 4 windings may be also secondaries, allowing various impedances to be added in series or parallel.

My next trick would be to connect the full primary to a Variac and wind it slowly up while monitoring the current flow on a DMM.

Long as the current stays below 100mA all the way to 230VAC, then you can find the secondary voltages, get ratios and be in business.

BTW: what does it weigh?

Any decent 100W valve output tranny weighs about 4 or 5kgs.


BTW2: 70 is NOT old !!



.... Phil

[Bo-Lennart]

Den fredag 27 september 2019 kl. 19:48:15 UTC+2 skrev Bo-Lennart:

Hi again....
Thank You for all Your suggestion about my transformer.
I would also like to thank You very much for the time You have spend for helping me to identify my transformer.

You had som question to me, and the answer is:
- The inductor-value between 7 and 8 should be in mH (not H) 3,08 mH
- The weight is 2,3 Kg (5 lb)
- Size is: height is 10cm (4 "), base: 8,5 x 9 cm.
I first tried out the transformer as a power transformer like this:
I feed power from a VARIAC to pin 4 and 6. It end up to 230V and the current stay as low as 13 mArms.
- Output at pin 7-8 gave 4,88 V
- All other windings gave 3,66 V
OK, then I tested it as a power output tansformer.
I input: 1 kHz at 1,0 Vrms (+ 2,3 dB)to pin pin 7 - 8.
That gave me these level at the diffrent pins /windings:
- 5 - 4 = 15,43 V ( +26 dB)
- 5 - 6 = 15,37 V ( +26 dB)
- 2A - 12 = 0,69 V ( -1 dB)
- 2A - 9 = 0,69 V ( -1 dB)
- 3A - 11 = 0,69 V ( -1 dB)
- 1A - 10 = 0,69 V ( -1 dB)

So, finally, I think that this transformer is a TUBE OUTPUT TRANSFORMER.
So now I will start to build me a tube-amplifier for my electric-guitar (it's a FENDER guitar).

And PHIL, thanks for Your comment about my age. I know that 70 is just a number. It's how You feel that will tell if You are young or old.

Best regards from SWEDEN

Bo-Lennart Karlsson
Falun, SWEDEN

[Phil Allison]

Bo-Lennart wrote:
------------------

>
> - The weight is 2,3 Kg (5 lb)
> - Size is: height is 10cm (4 "), base: 8,5 x 9 cm.
> I first tried out the transformer as a power transformer like this:
> I feed power from a VARIAC to pin 4 and 6.
> It end up to 230V and the current stay as low as 13 mArms.
> - Output at pin 7-8 gave 4,88 V
> - All other windings gave 3,66 V
>

--------------------------

** That adds up to a 40 watt rated output transformer, with about 4000 to 5000 ohms CT primary.

Try 400 to 450VDC B+ supply and a pair of 6L6GCs, 5881s or EL34s.

KT66s would also be a good option.

Load impedances from 4 to 16 ohms seem possible.

Have fun.


.... Phil