I'm wondering about that "neon".
Firstly if it is indeed a neon then maybe it's forming a simple white noise generator.
On the other hand, it looks a little bit too big to be a simple neon and I'm wondering if it's a different component all together. Way back when new components were coming out nearly monthly there was some type of resistor with peculiar characteristics which when incorporated into an oscillator circuit for example, would provide much enhanced stability. The name of the device escapes me but I do remember it was glass and it was used in a circuit design that I built from Practical Electronics.
I think the mixed vintage of components it typical of all electronics techs genetic blueprint of keeping everything no matter how old, "just in case"
- which again would pint to it been lab or home built rather than commercial.
