[morzh]

Eric

1. Good for you.
2. A piece of caution: this is a transistor generator. Transistors work at low voltages and get destroyed by high voltages. i did not analyze the sch too much but right off I do not see any output protection.
The C14 (I think) cap is what decouples the DC from the transistor's output, but:
a) I am not sure what he voltage rating of that cap is, and
b) This is not even that important as when you connect it to a higher than allowed DC biased load initial jump in voltage will get to the Q3 collector, and L2 in the collector only exacerbates it.

So, when using this generator with tube equipment, be careful when using it to inject a signal to a place which may have large DC bias.

This is what you get when mixing the solid state with tubes.