Ed Tuck founded Magellan in 1986. (Family photo)

Ed Tuck, an investor and electrical engineer, was flying his twin-engine Beechcraft Baron through the clouds of Northern California when he realized that landing his plane — searching for the narrow runway through a thick band of fog — was much harder than it should be.

It was 1985, and Mr. Tuck, an Army veteran, had heard about an emerging military technology known as the Global Positioning System. Dreamed up by the Navy and Air Force more than a decade earlier, GPS relied on satellites that were still being tested and launched into space and on bulky ground-based receivers that were expensive and difficult to use.

Though it was designed primarily for the military, civilian use of the system had been encouraged two years earlier, after Korean Air Lines Flight 007 wandered into Soviet airspace and was shot down. The incident appeared to be the result of a navigation error, and President Ronald Reagan declared that GPS would be available to airliners when the system became fully operational.

Yet there was little widespread interest in GPS until Mr. Tuck, who died June 26 at 85, brought the technology down to earth. As the founder of Magellan, he manufactured the first handheld GPS receiver for the general public — and demonstrated the mass appeal for a technology that has permitted smartphone users to find the closest late-night Thai restaurant; helped lost road-trippers pretend they know exactly where they’re going; and enabled countless schoolchildren to avoid learning how to properly read a map.

Mr. Tuck was forced for decades to remind people that he was not the inventor of GPS, a title that is generally bestowed upon Roger Easton, a physicist at the U.S. Naval Research Laboratory who died in 2014. He was also not the first to produce a small GPS receiver. According to Greg Milner, who chronicled the history of the technology in his 2016 book “Pinpoint,” competitor Charles Trimble already had made relatively small receivers for military and commercial use.

The first mass-market GPS receiver, the Magellan NAV 1000, sold for $3,000 in 1989. (Jaclyn Nash/Smithsonian's National Museum of American History)

But it was Mr. Tuck, a tinkerer who leapt from business to business, working at companies that produced everything from Mickey Mouse phones to optical character scanners, who insisted that the GPS could and should be shrank down to pocket size, without hurting the pocketbook. He also assembled the team and funding to make it happen.

Through his investment company, the Boundary Fund, he formed what became known as the Magellan Systems Corp. He hired the engineers Norm Hunt and Don Rea to develop software and hardware for his new device, which he hoped to carry in his shirt pocket and use on flights up the California coast.

At least 86 potential investors were unimpressed, perhaps as a result of Mr. Tuck’s un­or­tho­dox pitch. His product was geared not toward high-end Silicon Valley consumers but toward an ideal customer whom Mr. Tuck described as “Bubba.”

“Bubba is probably more south than Missouri,” said Mr. Tuck, who was raised in Springfield, Mo. “But I knew the culture, I knew what Bubba was like. I knew Bubba doesn’t like to admit he’s lost, and that if he found one of these under his Christmas tree, he’d be a happy man — if they were $300, of course.”

The device that Mr. Tuck and his team eventually produced, the Magellan NAV 1000, ultimately sold for $3,000 in 1989. It was waterproof, weighed a pound and a half, ran on six AA batteries and offered precision that was, Boating magazine wrote in a review, “pleasantly startling.”

When the global network of 24 GPS satellites became fully operational in the mid-1990s, Magellan and followers such as Garmin and TomTom became ever more popular and accurate. The company also was given an unexpected boost during the Persian Gulf War, when GPS had widespread use in combat for the first time. Many soldiers relied on Magellan’s portable units to coordinate their movements on the battlefield.

“I don’t think it’s nice to say that wars are lucky,” Mr. Tuck said of the timing. “But it was lucky that we had one at that particular time — if we were going to have one.”

A “breadboard,” or early mock-up, of Magellan's handheld GPS receiver. (Jaclyn Nash/Smithsonian's National Museum of American History)

Edward Fenton Tuck Jr. was born in Memphis on July 5, 1931. His mother was a secretary; his father worked as a mechanic for the St. Louis-San Francisco Railway, where he eventually became an executive. Mr. Tuck dropped out of high school to work full time as a producer for a radio station.

After graduating in 1953 from what was then Missouri School of Mines and Metallurgy in Rolla, he worked as a telecommunications executive at ITT Corp. before striking out on his own as an investor.

He eventually named Jim Whittaker, the first American to summit Mount Everest, as the chief executive of Magellan. The company was sold to Orbital Sciences Corp. in 1994 and is now a subsidiary of the Taiwan-based conglomerate MiTAC.

Mr. Tuck’s later business ventures included Teledesic, a partnership with Microsoft co-founder Bill Gates and telecommunications executive Craig McCaw that aimed to offer phone and Internet access across the world. It shuttered in 2002.

Mr. Tuck died at a nursing home in Charlotte, his daughter Jean McGregor said, and had chronic obstructive pulmonary disease. His wife of 60 years, the former Janet Barber, died in April.

Survivors include two daughters, Jean McGregor of Waxhaw, N.C., and Ann Tuck of Accra, Ghana; and five grandchildren.

“I used to tease him about how none of my kids can read maps thanks to him,” McGregor said. “He thought that was all right. ‘That’s too bad,’ he’d say, ‘but oh well.’ ”

Correction: An earlier version of this story incorrectly reported the impact of Korean Air Lines Flight 007 on the development of GPS. GPS was partly open to civilians by the time Flight 007 was shot down by the Soviet Union; it was not entirely classified. President Ronald Reagan subsequently declared that GPS would be available to airliners when the system became fully operational, but he did not single-handedly open it to the public.