If you need a new transformer think of it as an opportunity for an
improvement to the amplifier. The improvements could be higher plate
voltage, and perhaps using a separate transformer for the filament
voltage. By using a separate transformer for the filaments, with
multiple primary taps, you can adjust for optimum filament voltage. That
will give you enough emission and maximum tube life. Directly heated
cathode tube life is inversely proportionate to an exponential function
of filament voltage. A small reduction in filament voltage, while still
maintaining enough emission from the cathode, can greatly increase your
tube life.
If all the transformers have to fit inside the cabinet with the RF deck
and the HV transformer this may be difficult to the point of not being
practical. If there is a separate power supply from the RF deck, it is
much easier to do.
DE N6KB
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