Spanish-speaking audiences were receptive, but advertisers remained elusive, at least in part because KWEX was an Ultra High Frequency, or UHF, channel .

Television sets at the time were designed to receive about a dozen Very High Frequency (VHF) channels by default, and many of those channels were monopolized by the three main broadcast networks. Smaller stations were broadcast on UHF, which viewers needed a separate antenna and converter to receive.

This greatly restricted KWEX’s audience. But Mr. Nicolas said he used it as a selling point by taking potential advertisers to Mexican-American neighborhoods in San Antonio to show them UHF antenna s sprouting from the housetops . (This was before reliable viewership data was available .)

The limited reach of UHF made growth difficult, though, and Mr. Nicolas and Rene Anselmo, one of his partners, went to Washington to lobby Congress in support of the All-Channel Receiver Act, which would allow the Federal Communications Commission to require that new televisions include UHF tuners. The act became law in 1962, opening the way for Mr. Nicolas and his colleagues to expand.

The company soon became two connected entities: the Spanish International Communications Corporation, which acquired stations and affiliates in Los Angeles, New York and other major markets; and the Spanish International Network, which provided programming and arranged advertising for those stations . In the 1970s, SIN became one of the first networks in the United States to deliver its programming via satellite.

Mr. Nicolas, whose titles during his years at the company included president of S.I.C.C., helped the company expand to more than 200 affiliates nationwide. Hallmark bought it in 1987 for more than $300 million, a sale prompted by internal disputes and an F.C.C. ruling that too much of the company was owned by foreign investors. It adopted the name Univision shortly after the sale.

Univision — best known for telenovelas and the variety show “Sábado Gigante,” which ended its long run in 2015 — said that it earned $2.7 billion in total revenue in 2018 and that its programming reaches more than 95 percent of the Hispanic households in the United States, a population that is now approaching 60 million .