GDO

[Skywave]

Like this one Al:
http://www.sm0vpo.com/use/gdo.htm
Lawrence.

Yes, I have seen that cct. before. O.K., so the author says it works - and I expect a lot of people have built it and it works for them too: very good; I'm happy for them. But I still don't like the idea of creating an RF centre tap by virtue of the split capacitor and also creating another RF centre tap by centre-tapping the inductor. (That's if I read the cct. right - which isn't drawn very clearly.) Apart from the fact that having two RF earth points is unnecessary, unless those two points are always at zero RF potential, (which will be impossible to maintain over the entire freq. range that that GDO is designed to cover), the waveform will become distorted. This will lead to false dips and possibly weakened dips at appropriate frequencies.
I will also add that those conclusions are what I have found in practice, not just in GDOs but also with tuned L/C ccts. where two 180° phase signals are required.

Al.