Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
You could just splice on an extra length of cable, I have done this a couple of times "in extremis"
Make the joint as short as possible, less that one inch if you are dextrous.
Join the centre conductors, and insulate the joint.
Join the coax braid. If possible use a thin copper sleeve, if you cannot make a sleeve make the braid into two pigtails and join them, one on each side of the cable.
Use the correct impedance low loss coax for your extension.
If it does not work, use coax connectors.
Assuming the connectors are the standard Belling-lee connectors (You have not specified the type.) you can get ready made extension cables such as this one. You will probably not get one as short as 150mm. The only other type of connector I have seen used for TVs is the "F" type connector but that would be unusual. "F" connectors are normaly used on the cable between the LNB and satellite receiver.