http://www.aerialsandtv.com/rfmodulators.html
The above link will take you to ATV aerials Sheffield, used these guys for a long time & should you be into aerials..leads splitters ect, make a cup of tea & read through the site.Use this RF modulator on my replacement Samsung box, max five mins. to install.
Also as a try for a Tivo with only one scart. -connected a powered scart (one in two out) ie. virgin service scart cable in...one out to TV... one out to RF modulator...co-ax round the house perfect so far. NB.Tried this using one cart on the Samsung. Works with HDMI in use.