Huge Lesson Learned!!!

[Skywave]

Y'know, I've never been really sure about the reason for fitting that cap. across the mains input: I always thought that it was primarily there to by-pass any high-frequency 'noise' - such as fast-rising spikes, random R.F. signals and such like coming down the mains lead. As for suppressing hum - as in modulation hum - the usual trick consists of capacitor(s) from the anode(s) of the rect. valve to chassis.

Have I got all that about right?

Al.