I got the adapter and screwed onto two-line amplifier. When the screw parts to the multi-switch, is immediately the press connection to the mother worked. That is broken! For 1.20 euros I was too lazy to return the part. I assembled it again and made tape it. Holds and works. Nevertheless, the adapter should not be tinkered so fiddly that it breaks down the screw by hand. Had I used an open-end wrench, I would give me a guilt ...
An adapter tinkering with two F-connectors and a few cm coax cable is securely stable ....
