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Thordarson Transformers

Ernst Erb Martin Renz Vincent de Franco Miguel Bravo-Cos Mark Hippenstiel Alessandro De Poi Heribert Jung Bernhard Nagel Eilert Menke Dietmar Rudolph † 6.1.22 
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Forum » In General » Thordarson Transformers
Jeffrey Fisher
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14.May.09 15:55

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I am looking for information on some Thordarson transformers.  They were part of a very strange piece of equipment built sometime in the 1940's I believe. 
At least some of them are audio transformers as that is what they say on the outside!
I have looked on the web but it seems as though most of the catalogs stop around 1941 and the units I have aren't in there. 
The numbers are as follows:

T-51751  power transformer 2 115V 60CY(!) primaries  1000V 2MA (mega or milli? it is written in capital letters)  2.5V 2A

T-49437  2 pins possibly a choke?

T-49436  output transformer (written on the case)  ratio p/s .485/5.9  on the pin side
(2) S.2,  C.T., P, B, 600ohms  (possibly a push pull line output transformer?)

T-51449  4 pins and quite small

T-49428-A  6 pins also small

The unit also had an UTC A-26 grid to line output transformer which I found info on relatively easily.   I would really appreciate any help finding more information on these pieces, I'm certainly hoping to find something useful out of them! 

Thanks for your time


Jeffrey Fisher

Emilio Ciardiello
Emilio Ciardiello
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17.May.09 08:30

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Dear Jeffrey,

in the fifties standard Thordarson transformers were identified by a five digit code. Is it possible that the codes you are reading in your equipment are custom ones?

From your description, T-51751 looks as the power transformer for the HV accelerating potential of an oscilloscope or some small CRT. The 1 kV, 2 milliamps winding goes to a 2X2A or similar HV rectifier, whose heater is connected to the 2.5V winding. The T-49437 should be a choke because of the two pins.

May be that you can have more information about the windings looking for the technical manual of the equipment, if a label is still available on its cabinet.

Regards, Emilio

Hans van der Puijl
Hans van der Puijl
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31.Dec.09 02:49

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Asfar as I can remember is that ouput transformer for a push-pull output circuit with taps for screengrid connections for 2xEL36 or equal. Named Ultra Linear.Thordason transformers where very popular for that type of circuit because of the bifilar winding  but they where not cheap.

This article was edited 02.Jan.10 10:00 by Hans van der Puijl .