Christian McArdle wrote:
snip good advice

15m = you might well be lucky anyway
15-30m = an aerial side booster will help you achieve near enough 100%
30m = you might struggle to get a 100% decent connection (although it
might work a bit)

A quick mental tot up says around 15m. I think there is one permanent
splice.

You could also replace the cable from the aerial through the loft and down
the wall and just convert to the crappy cable for the concealed section that
is too difficult or expensive to replace. If you do this, you must take
great care to make a waterproof splice as the cable will be massively
affected by water ingress.

This would be possible. the run is outside until it comes in under the
suspended floor, so I could easily stick an IP65 box on teh outside of
the house and join the two parts.

Thanks for the comments - I do at least feel like there is some hope
now!

--
Steve F