Why was Channel 3 and 4 rarely used on North American analog broadcast TV?
By - thenebular
They were commonly used. But it was very rare for someone to live in an area where *both* channels were used, since the FCC would spread the channels around to avoid interference.
Ok, now we're getting somewhere.
Which is why there was usually a selector switch to choose 3 or 4 on the device.
it was rare that they were both used for the same area. this was intentional so you could hook up your other electronics and to avoid overlapping signals.
Channel 3 was used in Omaha. It's used in Boston.
These reasons probably went pretty hand-in-hand with each other
Channel 3 and 4 were mainly used as modulators for consumer devices were cheaper to make and more stable at ~60 Mhz than they were at ~400Mhz. They also did not use Channels 2,6,7, and 13 as there was a risk of interference to radio bands adjacent to those channels if there was RF leakage or secondary harmonics.
Every one of those channels were used in the 80s and 90s in the Toronto area.
They weren't used for RF modulators for those reasons. They were assigned to TV stations as they have better control of their RF emissions than a consumer device.