Okay, here is the antenna mounted on a 30 meters mast.
A 4-way splitter is used to connect them. Call it stupid or call me stupid, the most important thing to me is to get it to work properly eventually. It is working now, but it is not optimal of course as you can easily tell.
I will try to summarize my issues:
I have got a Mizar FM transmitter that feeds its output to this FM amplifier:
https://www.electro-tech-online.com/threads/ac-power-requirements-for-this-fm-amplifier.120852/
Originally the radio station used to give 20 Km range. The Mizar was connected via a LMR-400 series cable to an omni directional antenna mounted vertically. Now, the mizar is fed into the above mentioned amplifier, and then the amplifier is connected to the label-italy antenna array via a 50 meters cable(couldn't find a name or rating for it).
1- I understand it is just better to use 1000 watt amplifier than using an amplifier to boost the signal of an existing transmitter. Right?
2-The amplifier has a 7/16 Din female RF out connector. I couldn't really connect it firmly due to lack of tools. I think that's an issue.
3- The feeding cable itself could be just bad. I think I should replace it with a LMR-600 series cable.
4- The antenna might not be 50 ohms so a mismatch is there. That only or maybe the antenna system should just be modified altogether as implied by you.
Sorry I had to type this quickly...
Thanks folks.