Thank you Carl K1MH, Vic K2VCO and VK3PA for their response to my question.
The transformer fitted to this example of the 76PA is the more efficient
option that was on offer at the time of manufacture. Should the transformer
fail, I do not think it could be rewound because it has a thick black
coating, it has most likely been impregnated and then dipped. In the UK the
amplifier will not be run at more than 400w and so the power supply will not
be stressed, but the losses within the transformer, manifesting as heat are
of concern to me. But I had realised that the fan would turn slower when
running on the 50hz supply and part of my refurbishment plan is to change
the fan to a DC unit with the equivalent or greater air flow, which may help
with the transformer heating.
However, I think that my first experiment will be to power up the
transformer on its own, before installing it into the amplifier, and see
just how hot it becomes, keeping a close check on it, say every 15 minutes,
if it gets warm to the touch, but no warmer, and remains that way, then I
will install it into the amplifier. But, if it gradually gets hotter, to the
point where you could "fry and egg on it", that would mean I will have to
obtain the 50hz replacement.
Thank you once again for your advice, sincerely, John. G3JVC.
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