Krim's tale

It turns out that 89-year-old Norm Krim is not only Raytheon's archivist, he's a living link to the roots of the electronics industry. He's also the father of the CK722 [see photo].

Photo: LARRY VOLK

Norman Krim, father of the CK722 that Jack Ward bought as a child, is now curator of the Raytheon archives. Here he sits at his kitchen table and plays with a CK722 radio made and presented to him by Ward.

Late one chilly night this past October, as he and I sat in the kitchen of his Newton, Mass., home sipping green tea and munching on roasted almonds, Krim spun his story. Having been a student of Raytheon founder Vannevar Bush at MIT, Krim took a job with his mentor's company as an engineer in the receiving tube division in 1935. By 1938, Krim had developed subminiature tubes for hearing aids.

The expertise gained in that work earned six patents on the subminiature tubes found in the proximity fuses used in U.S. Army artillery and antiaircraft shells, credited by some historians with turning around the Battle of the Bulge in late 1944. After the war, under Krim's steady hand, Raytheon's receiving tube division dominated the market for hearing-aid tubes with a 90 percent share through the 1940s.

As the industrial war machine was winding down, the semiconductor revolution was just revving up. At Raytheon's archives in Lexington, the morning after our late night bull session, Krim showed me a letter. Dated 9 July 1948, it was addressed to Laurence K. Marshall, then president of Raytheon, inviting him to Bell Telephone Laboratories Inc. (Murray Hill, N.J.) to see a demonstration of "a new device called a Transistor," specifically the point-contact transistor invented by Walter Brattain, John Bardeen, and William Shockley. Marshall was busy that day and tapped Krim to go in his place. What he saw shook him to his very core.

"I was worried that my success had been with tubes, and this was threatening my job," Krim recalls. "So what the hell was I going to do? I was going to get into transistors."

Krim's crash program eventually led to the introduction of the world's first commercially available transistor, the CK703 in 1948, less than six months after the Murray Hill demonstration.

But the CK703 had some problems. The germanium point-contact transistor—actually two pointed wires, 125 µm in diameter and 25-50 µm apart, in contact with the signal-amplifying semiconductor—had to be handmade with watchmaker precision, which precluded cost-effective mass production. And they were none too robust. The slightest shock could ruin them, which made them useless for hearing aids and just about everything else.

So Krim shifted gears and leveraged his division's growing expertise in semiconductor technology to make germanium diodes, which had a ready market as signal detectors in TV sets. By 1950, Raytheon was cranking out 20 000 diodes a day and Krim was promoted to vice president of the receiving tube division, where the diodes were being made.

Double jeopardy

Meanwhile, as germanium diodes and subminiature tubes poured out of Raytheon's plants, William Shockley was about to jolt the world again, this time with the junction transistor. Krim was fortunate enough to room with Shockley for over a week in the spring of 1951, while both were serving on a military procurement advisory board known as the Baker Committee.

"Shockley would be proofreading a paper after dinner every night. He told me, 'I'm going to publish an article in the Physical Review, and you should remember, pick up that article.' When I got a copy of his article on junction transistors, that was it for me. The light bulb went on." And Krim's engineers swung into action.

Their junction transistors were simple devices made of two indium dots (emitter and collector) alloyed to either side of a germanium chip. But the germanium wasn't pure enough and the initial devices failed. Later in 1951, at a symposium conducted by Bell Labs, Krim's team learned the value of zone refining: passing an RF coil over a quartz tube containing a large block of germanium crystal and melting portions of it in sequence. That got the impurities to migrate to the end of the ingot, which could then be lopped off, leaving a pure crystal behind.

Knowing that quartz tubes were key to making germanium pure enough for junction transistors, the crafty Krim cornered the market on quartz tubing. "And I did one other thing," he says with a sly smile. "There was a company in Missouri called Eagle-Picher, at the time the country's biggest zinc refiner. They threw out germanium as a byproduct of zinc refining. So I bought it all up."

But as Raytheon prepared to introduce its germanium junction transistor, dubbed the CK718, yields stayed stubbornly low. Water vapor and other environmental contamination occurring during the manufacturing process were to blame. To get around the problem, Krim's team used infant incubators as "clean boxes," so technicians wearing rubber gloves could reach in and assemble transistors while minimizing exposure to ambient conditions. Yields went up, and by the end of 1952, Raytheon released 10 000 CK718s to its commercial customers, the hearing-aid manufacturers.

Kids' stuff

Still, the manufacturing process wasn't perfect, and Krim was stuck with a mound of noisy, low-gain CK718s that weren't good enough for hearing aids. Faced with the prospect of destroying thousands of rejects, Krim, who a decade later as CEO of RadioShack would sell the electronic hobby retailer to leather craft store chain Tandy Corp. (Dallas), wondered: could what was scrap to a company be gold to a hobbyist? As a youth in the late 1920s, he had built a mechanical TV set. It included a radio receiver and a Bakelite disk drilled with 16 strategically placed holes to scan a Raytheon Kino neon lamp that projected the picture. Resourceful even then, he used his mother's milkshake mixer to rotate the disk and obtain an image.

"I thought, jeez, wouldn't these rejects make a hell of a good thing? So when the guys wanted to break them up, I said, you can't do that—they're worth something," recalls Krim. "I loved to build experimental stuff and I just wanted the kids to have these. And nobody had ever seen a transistor."

Not even editors of the major electronics publications at the time. So in February 1953, Krim invited the editors of all the major electronics magazines, including Electronics and the now defunct Radio and TV News, to his office for a demonstration of CK718 rejects that were relabeled CK722. "Their tongues were hanging out," recollects Krim.

From the pens of those amazed editors the word spread about what the ordinary hobbyist could do with a transistor. And kids across the United States started putting together radios and oscillators and speakerphones, a few of which are now enshrined in the Transistor Museum.