I bought a caravan its a coachman 530/4 2004 i am new to caravaning and looking for a bit of help cant get tv signal from mast with amplifier plugged in but as soon as i unplug it and put aerial directly into the tv i get signal so i assumed my amplifier was broke sp i have bought a vision 355 and vp3 amplifier now when i have looked on roof at old aerial i cant see any grub screws so i think i might need to carefully cut it off to replace has anyone any advice? Its a old vision amplifoer so i am assuming its an old vision aerial?