"VF" ???Watch out on the VF with brass tubing on a stripped 50 ohm LMR400 guys,
You could treat yourself and try to make a coco with the mother of coaxials, Andrews Heliax LDF5-75 (a 75 ohm cable for a 75 ohm job),if you can get it..the 50 ohm (LDF5-50) is more popular.
No faffing with tubing as its already in the cable makeup..Here you will be in the company of the elite of coaxial cables, Andrews are always batting at the top of their game on heavy duty microwave feedlines but, a caveat..connectors will put a serious dent/ouch in your wallet.
A hardline N connector is anything between $75-$125 USD, yes thats each !
I dont trust my weak soldering skills with a connector of this expense.
I would recruit xforce,jepolch,tom or bramj..well worth the return postage !
Davis RF will have and sell this by the foot I imagine.
Off topic, To model maker extraordinaire @jepolch,
I found a very interesting page via flightaware about the demise of the Russian space shuttle program, made very sad reading..what a travesty.
Sorry for the neub question