After I have long searched for radio triggers for Pentax K3, I have now found the right thing. At least the flashes are triggered correctly on the Pentax K3. I have not tried because I do not need the possibility of remote control of the camera. Triggering to trigger lightning. Also Meike MK-RC7 have worked. But since I Yongnuo flashes and now also the flash controller 560-TX have, the exchange offered, since I now perform with the TX all my flashes and for the 560-III no additional receiver more consumption.
So I'm very pleased with the transceivers of Yongnuo.
And best of all, I'd almost forgotten: the CII has the switch now to the side. Is thus no longer covered by the flash. Thanks to Yongnuo for implementing the feedback from practical experience.