US mandate was March 1964 IIRC. Any new sets had to have UHF
& NOS could be sold off. Canada came later with there mandate. Probably
most Canada sets after the mid 60's had UHF to get all the UHF from US stations. There was a second US mandate apx 1974. UHF had to be
as easy to tune as VHF. Thats why detents got added to UHF tuners or
the set had varactor tuners with presets.
73 Zeno
LFOD !