[Central-Electronics] 100V VFO questions?

[Eugene Hertz]

Hi All,

Trying to decypher the VFO portion of the 100V schematic.  Two immediate questions.

1. In the VFO circuit, I cannot seem to locate where the "variable" component is that is driven by the main tuning dial. I would expect to look for either a variable cap or a slug'd inductor (like a pto).  Yet looking at this part of the diagram I only see something called a "tuning corrector" which doesn't sound like the main tuning dial. Can someone point me to where this is?

2. I see there is a neon lamp NE-2 in this circuit. Can anyone tell me the function of this lamp? Also, if this lamp were to be old and aged, what affect could this have on the VFO?

3. STRICTLY ACADEMIC QUESTION: Has anyone ever tried to replace the 0A2 tube with a solid state Zener? One that comes to mind is NTE5226A which is a 10W 150V zener. Would there be any benefit to this? Stability? Lower heat generation? 

thanks!
Eugene