A good way to understand the circuits of the BITX is to run circuit simulations. This allows you to do "what if's" and also investigate the waveforms found in the design with out having expensive test equipment. LTspice is a free and very versitile program after a learning curve. It has a yahoo group at LTspice yahoo group that is moderated by the programs designer and help is readily available.
I have some of the BITX circuit files listed below. Using them will eliminate you having to draw them and allow you to start right away. I would highly reccomend running some of the tutorials that come with the software to get started.
To use these files, click on the link and save them to your LTspice examples directory. Then you can load and run them.