DCF77 radio clock module

I'm using this module.

Output should be inverted as far as I know after reading the manual.

I'm not getting any time by using the arduino-library for dcf77.
The LED on the device is blinking some kind of nervous.
On youtube I saw that the signal-impulse of the LED should be every 5 seconds...

You have not said where you are living ( it is handy if you put this on your profile )
Presumably it is Germany ?

I got another receiver working. But after activation my bluetooth-module will cause interference and the receiver doesn't work anymore.
Is there a way to protect the receiver-wires from the bluetooth? Some metalized interlayer?
I already used a cat5-patchcable to move the antenna away from the board.

I would recommend separation and a Faraday shield try to get the DCF77 radio as far away as possible from the controller and use both a Faraday shield and shielded cable to the Antenna. You will have to compensate for the added cable capacitance when tuning the antenna. Measure the cable capacitance disconnected from the antenna and reduce the tuning capacitance by the measured capacitance.