My old Color
Computer used US VHF channels 3 or 4 for NTSC video. I found a reference to the ZX
Spectrum
using UK UHF channel 35 for PAL video.
My NTSC ZX81 uses US UHF 34/35.
Most, if not, all home computers sold to connect to TVs in the UK were set to use our UHF
channel 36. They
normally used an Astec modulator unit, and a careful tweak of the oscillator coil core
would move them onto
other channels.
VHF channels were not used for broadcast 625 line TV in the UK, and most TVs could not
tune to them. So you
will not find a UK home computer using VHF RF output.
-tony