Why only 2 stars? not met or requirements

Meanwhile, hang on our cable 2 distance rather with 10 or 15m cable. Wherein at the 10m segment in addition to the TV, a mini-PC is still connected with 2 USB TV receivers.
The TV is set to HD for the public service. To the signal in the 10m Segement improve I run for some time an antenna amplifier, which is not, however, be regulated. I wanted this amp like to replace it with a controllable amplifier and have therefore ordered me this amp.
The new amplifier should be connected directly to the transfer point (the TV outlet so) that there built tee therefore was removed, as well as the previously used broadband amplifier.
After that I tried to adjust the gain so that were Overdriven on TV so far neither the strong station, nor the weak signals were not sufficiently reinforced.
The small knob makes this setting is not easy, but not entirely impossible.
My television shows me the signal strength and signal quality of the signal strength was not changed by the amplifier, but the quality could be affected - positively and also negative, which is also normal.

What was, however, I noticed that the setting with the slightest pressure on this knob changes (inserting the screwdriver).
Slight movements of the amplifier also changed the signal quality significantly to negative.

Short yet to Lieferumpfang:
In the box you will find the amplifier, fastening material for wall mounting, 2 adapter to the TV cable to the sockets of the outputs to connect and a Quick Start Guide.

To connect a cable so the antenna socket is still required to the amplifier - not in the scope of delivery.

My Conclusion:
For me useless and therefore returns.