Bill wrote:
Son wanted to do a "proper job", so alongside his RJ45 patch panel under
the stairs, he installed an RF/Video panel full of F connectors.

He has run the cables which are RJ59 and similar,

You mean RG59, I guess. The term 'RG59' is now meaningless. It was
originally a military spec. There are cables sold as RG59 that are
suitable for UHF and SAT, but there are also some that are too 'lossy'
for those applications. Some are really only suitable for CCTV. These
have a solid dielectric. They are no good for SAT and not very good for UHF.

Bill