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The
First RCA Transistor Radios
by Thomas Stanley
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Dave Holmes,
drawing on a paper about vacuum-tube amplifiers written in the thirties,
pointed out that "maximum available gain" as a measure of transistor
performance meant little; he defined "maximum stable gain", which
made practical the heretofore mysterious process of high-frequency circuit
design. Many at RCA Laboratories
were by now developing transistor circuits. Our common objective was a grand several-days show-and-tell
for RCA licensees and industry leaders.
We'd patched together a guitar amplifier, a personal pager, and a
phonograph amplifier. Loy Barton
contributed a much improved “personal portable” radio. Most spectacular,
hands down, was the transistorized TV set that Jerry Herzog and Bob Lohman
had built under the guidance of George "complementary-symmetry"
Sziklai. They ingeniously used
point-contact transistors where the needed high-frequency performance was
beyond that of junction transistors, and an oscilloscope-like display, but
it was nonetheless spectacular. For
this show-and-tell, reject transistors had been glued to poster boards. Fortuitously, we later discovered that while these
transistors had failed some static tests, they exhibited unusual
high-frequency performance when suitably operated. We retrieved them, and many found their
way-- still with glue and cardboard skin on one side-- to the r-f and mixer
stages of our radios. And radios it
was. We were called upon to
replicate our elegant personal portable radio by a half-dozen or more for
various big wigs.
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The
First RCA Transistor Radios
by Thomas Stanley
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None,
though, for Larry, Dave or me; management had not yet heard the maxim
"Thou shalt not muzzle the ox that treads the corn" that Bill
Webster was fond of invoking years later, when he deservedly became
boss. After the personal portable,
we engineered an automobile radio, meeting or exceeding the test
specifications of a top-of-the-line auto radio then in production.
Engineers from the manufacturer (not RCA) came to see what we'd done. We showed comparison performance curves,
including some that were fairly arcane.
In one such side-by-side comparison, our guest engineer pointed out
that the illustrated performance would never do, until he was alerted that
he was speaking of his own product.
We were told that an auto radio must be operable over a temperature
range from 40 below zero to 80C above.
Ours was, with only moderate loss in performance at the
extremes. The old, leaky test
chamber in which we made these measurements accommodated a brew of dry ice
and cellusolve acetate, and Larry became deathly ill for a day and a half
from the fumes. Our last hurrah,
years after the Herzog-Lohman triumph, was a twelve-inch portable TV that
could compete with any small commercial set. As I recall, for the high-frequency circuits we may by then
have had the benefit of the drift transistors that Bill Webster, now in our
Semiconductor Division, was turning out.
Horizontal deflection was a challenge-- the yoke was direct-driven--
but Joe Preisig ultimately succeeded with a circuit that stacked two
transistors.
Go
To Stanley, Page 4
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