For the reception of Radio Frieloo on 6290 kHz I received a friendly QSL email from the operator. I sent my report to frieloo(at)outlook.com .
Radio Frieloo is a pirate station operating from the province Gelderland in The Netherlands. The operator told me that he is not often in the air. When it is the case it is mostly to test antenna designs. The transmitter is a R&S with 100 Watt as shown in the picture.

Today Wednesday April 16th signing off at 1640 UTC as Radio Mona Lisa.
HI Joé. Trust all is well, and good to hear from you again.
How did you know it was the same station?
73s, Peter