Unitran (Netherlands)

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Well-known member
Mar 27, 2013
Here's a Unitran (Holland/The Netherlands) 11A18SS input transformer that recently gave up the ghost. It actually might have been dead for quite some time, but I tried the preamplifier it belonged to for the first time today.

The ratio of the 11A18SS is 1 :445/14 according to an old Unitran catalogue.  Primary is 50/125/200/333/500/600 and secondary 100k p-p, i.e. dual grid (CT). Response is rated at 15-30.000 +/-1dB  (which doesn't match the stamping on the transformer).

I've never performed any transformer surgery before, but I had to open this up in hope of finding a loose wire. No luck. One half of the secondary is dead.

- That guck is probably hazardous.
+ Nice magnetic screen

Unitran is/was probably most famous for their Williamson output transformer (which has stunning specs - readily available on Google). The transformers themselves are as rare as hens teeth


Anyone interesting in continuing the surgery?

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