While Cecil is right about TV Channel 1 being dropped to make room for other users, he neglects to mention that the stations that were “Channel 1” were quite happy to move. There are some propagation problems at those frequencies that don’t bother a low-power, short-term user like a police conversation, but would bother a broadcaster. Depending on the weather and sunspot activity, a high-power Television signal in that frequency (40 mHz) can be seen quite well half-way around the world, but unable to be recieved 10 miles away. This effect can come and go very quickly. A bit of a bother if you’re watching “Seinfeld” - or maybe not. A two-way radio user can just ask for a repeat.
It’s a similar effect to the “skip” in AM and Shortwave, but the cause is different.
Mark Tomlonson
Chief Engineer, WMUK
Kalamazoo MI