Saw this simple GDM:
And decided to give it a try.
It's just simple because the generator part of the circuit is omitted...
I didn't needed the 2k2 pot (was set to zero) and the diode used although also "Ge" didn't had markings.
"Generator" was the MFJ.
On the following photo is the "dip" on a LC test circuit:
Here's a no "dip" situation:
Control was made using my trustee dip meter...
Lot's of info on dip meters at: http://www.noding.com/la8ak/m11.htm ,
unfortunately LA8AK is SK but his family still serve's his nice pages at: http://www.noding.com/la8ak/
Have a nice weekend.