In my surfing of Wikipedia, I found two different television networks that were both initially called NET.
The first was founded as the Educational Television and Radio Center (ETRC) in November 1952 by a grant from the Ford Foundation's Fund for Adult Education. On May 16, 1954, it began airing a daily five-hour package of programming, featuring a lot of what its successors would also have: adult educational content. After another name change, the organization was renamed National Educational Television (NET). Because of NET's need for continuous additional funding, the Ford Foundation started to withdraw financial support. As a result, the U.S. government created the Corporation for Public Broadcasting (sound familiar?) in 1967, with the corporation's intent being to create its own public broadcasting network. This was because affiliates felt alienated by the NET programming offered (which often included hard-hitting documentaries that were considered too liberal for the conservatives of the day). NET refused to stop airing their controversial programming, and were shut down by Ford and the CPB in 1969. In early 1970, NET merged with affiliate WNDT-TV to avoid funding cuts. On October 5, 1970, the exact same day the merger was completed, the Public Broadcasting Station (better known by its acronym PBS) began broadcasting.
The second NET started in 1957 as Nihon Educational Television Co., Ltd. in Japan as a for-profit, educational channel, a rarity even today. When this television model failed, NET gradually changed into a general-purpose station, with programming like anime and foreign films, justifying the airing of these under the pretexts of child emotional development and introduction of foreign cultures. In 1960, the name of the channel was changed to NET TV, airing its first color program in 1967. By 1973, the channel was a full-fledged general-purpose station, the same year NET TV was renamed NET General Television. On April 1, 1977, the channel's name was changed to its present moniker, TV Asahi. TV Asahi's probably best known outside of Japan for airing the Super Sentai incarnations (the Japanese original version of Power Rangers).