Thanks for the continued advice guys. To rule out a problem with screening I bit the bullet and bought some new pf100 cable and installed that direct from one of the F terminals on the aerial to our second bedroom TV set. It has far more copper braid than the stuff I had been using and seems to have solved the problem with a good strong signal on all but a few lesser channels. I'm wondering whether I can sort this problem out by moving the aerial a little (trial and error) or 'fine tune' those channels to improve things?
The main issue I have now is that if I connect the cable to the set via a normal coaxial plug there is no signal at all. If I disassemble the outer threaded metal barrel however and just push the metal screw-on pin into the rf socket it works fine. I'm at a loss to explain why a simple coaxial socket would cause a total break in the signal - I've fitted quite a few in my time and never had such a problem so I'm stumped as to what might be wrong.
