[stuarth]

The circuit in post 15 shows a ring with 2 inductors. To avoid excessive voltage drop, those inductors must have a low resistance. Adding essentially lossless reactive components such as inductors or capacitors does not necessarily stop oscillations, what you need to do is absorb the unwanted HF. Hence the (single) resistor in the loop. Any valveholder has a low impedance LF connection through one side of the loop, but HF sees the whole loop including the damping resistor.

As I said, I don't know if they used it, or how effective it might be.

You might get a similar effect by using a capacitor with a 200R damping resistor (you
can buy a capacitor + resistor as a single component for such things a switch click suppression) to decouple each pin, but if the resistor in the loop works, it would obviously be cheaper, you wouldn't need all those high voltage capacitors.

Stuart