Sorry about all the posts I wanted to clarify that
I was looking for a Vacuum Tube model signal Generator
schematic. Thanx Brian

Hi:
I have the schematic for the Heathkit AO-1 audio oscillator, using two 6SN7s and a 6X5. It appears to use standard parts, except for a "thermistor" with no identification.

Of course it would be easier to restore an old H-P 200CD: if you were in eastern Massachusetts I'd give you a rack-mount 200CDR, but I really don't want to pack it for shipping.