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Unknown PP output transformers

ellejammer

Member
2009-02-15 7:11 am
Hi everybody,

3 years ago I got on the bay a NOS pair of identical PP output transformers.
The end bells say respectively:
FT4725698-138305E and FT4725698-138217E
The core is a 1_3/4 inch stack of EI 1_1/8 inch lamination
Primary inductance is about 250H @ 5Vrms, 50Hz, plate to plate with a DC resistance of 125+125 ohm.
They weight 2.2Kg each and look like an A470, maybe a bit smaller...
Nominal impedances, from voltage ratio measurements, are:
Primary: 7.0 Kohm plate to plate
Second: 0-8-16-32 ohm, tapped

Does anybody know the manufacturer and their use ?
Thank you, Franco