Apologies for writing this in English, but my English is better than my German...
This is a kit, which is ONLY designed to work with super-regenerative receivers. The instructions included with the kit show how to make it work with the "Franzis-Röhrenradio" and the "Retro-Kurzwellenradio". I believe it could be also made to work with other homemade super-regenerative receivers.
However, BE WARNED! It will NOT work with almost all commercial radios (made after about 1930); these are super-heterodynes, not super-regeneratives.
In short, I definitely recommend it if you have built (or are planning to build) a Franzis-Röhrenradio, a Retro-Kurzwellenradio or a similar super-regen, whether valve or transistor; but don't buy it to get your EXISTING radio, new or old, to receive DRM.