Hello Armin,
Then the 2 m Coax, especially the outer conductor, acts as a part of the antenna. One of my setups with CMC is descried here.
If you compare the right CMC (in the picture) wit the film can you see, there is not much room left. The female BNC connector is long inside the can. It’s one to mount on a coax cable. I like it because of the reliability. The toroid is long to increase the conductivity. The number of windings is limited by the inner diameter of the toroid. Using the mentioned DG0SA system would not allow noticeable more windings to compensate the lower productivity by a shorter toroid to get more room for a second core.
73, Ludwig