Identify Output Transformer

[BigClick]

Hi folks,

I am hoping to get some information on the operating values of an unknown transformer, see pic attached.

It came out of a self-build Mullard 5-10 amp

I have measured resistance across all combinations on each side.

I would like to know what the primary and secondary winding impedances are but I don’t know how to work this out from the DC resistance or in fact if this is possible. I am hoping the fact it came from a popular vintage amp will help.

I also would like to know what the windings look like in relation to the wires.

Any pointers would be welcome,

Ray

[Ed_Dinning]

Hi Ray, it looks like one of the many that were produced by various firms for this popular amp. The 2 primary halves have the sec windings wound in the middle of them, hence sec resistances are about equal while primary resistances vary a lot due to the different mean lengths of turns.
Red is HT+, the two yellows are either anodes
The sec windings will have been connected in parallel for 4R and series for 16R.

If you apply a low voltage 50Hz signal you will be able to work out the turns ratio and phase relationships between the windings.

Ed

[WaveyDipole]

There is also a detailed description of the self-build Mullard 5-10 amp here:
http://www.r-type.org/articles/art-003e.htm
Near the bottom where it provides the component list, it mentions some of the transformer brands and types that may have been used.

I did wonder about that diference in measured resistance, but Ed has already provided the explanation.

[BigClick]

Originally Posted by Ed_Dinning

Hi Ray, it looks like one of the many that were produced by various firms for this popular amp.

Brilliant thanks Ed

Originally Posted by WaveyDipole

Near the bottom where it provides the component list, it mentions some of the transformer brands and types that may have been used.

Cheers WD. I might try and look up a few of those in addition to trying out the phasing test explained by ED.