Minty Motorola 9T1 restoration

[bandersen]

Good point, adding a small cap across the diodes is a good idea. Also, there are bypass caps and series inductors through the filament string that help suppress noise.

Heat. The ballast kicks out around 30 watts. Hot enough they put a piece of asbestos above it to shield the cabinet.

Also the ballast doesn't act quite the same as a fixed resistor. Especially, if an Amperite regulator type is used. They resist the current surge when a cold set is turned on. Sort of like a modern thermistor.