Valve Crystal Oscillator Grid Current

[pwdrive]

There is a good description of a very similar xtal osc to that in John's schematic in the link below, it starts at the bottom of book page 64.

http://books.google.co.uk/books?id=f9QXAAAAYAAJ&pg=PA66&dq=%22crystal+current%22&hl=en&sa=X&ei=5aYIVNDsKorH7AapgoHwDQ&ved=0CDcQ6AEwBQ#v=onepage&q=%22crystal%20current%22&f=false

Lawrence.