- The superheterodyne method
is where two signals are mixed together
to make a lower frequency signal
that is easier to deal with.
And according to Wikipedia,
"virtually all modern radio receivers
use the superheterodyne principle."
But how was it invented?
How does it work?
And what does that have to do with
how radio became so popular?
This is the story of Howard Armstrong,
who invented it in the middle of a bombing raid,
and David Sarnoff,
who used Armstrong's inventions
to fulfill his improbable desire to make a broadcast empire
with himself at the helm.
Ready for the story?
Let's go.
♪ Electricity electricity ♪
Let's start with David Sarnoff.
Sarnoff was born in the Shtetl in Minsk, Russia in 1891
to poor Jewish painter.
Think, Fiddler on the Roof, but with a painter.
When Sarnoff was just a boy,
his father left Russia to go to America
to improve their fortunes.
But when Sarnoff, his mother,
and younger brothers joined him in New York,
Sarnoff found that his father was unable to care for anyone.
At the tender age of 9,
Sarnoff became the breadwinner for the family.
Years later he recalled that quote,
"It was like being tossed into a whirlpool,
a slum whirlpool
and left to sink or swim."
Sarnoff's interest in wireless
began when started delivering telegraphs
for the Commercial Cable Company.
He was actually looking for a job with the New York Herald,
but he accidentally opened the wrong door.
Sarnoff then spent a precious $2
out of his $5 a week paycheck
to purchase a telegraph key.
And he then taught himself how to be a telegraph operator.
Soon, he switched to working for the Marconi Company,
where he was occasionally allowed to send wireless messages
when the main operators were sick.
One day in December of 1906,
Guilermo Marconi himself visited his New York office
and the bold fifteen-year-old
introduced himself to the big boss.
They had an instant report
and at the end of the evening,
Sarnoff became Marconi's personal New York message boy,
which mostly involved deliveries
to Marconi's many mistresses.
With Marconi's patronage,
Sarnoff became a junior telegraph operator.
He moved off to being a local manager by 1912
when the Titanic sank.
Sarnoff then created a story
where he was the first to hear of it in the United State,
he wasn't.
That he was the only operator working, he wasn't.
And that he stayed up for 3 nights straight
to hear the news, maybe.
Due to his heroics,
he was promoted to chief inspector
and right hand man to the general manager, Edward J. Nally.
The next year, in 1913,
the 21-yr-old Sarnoff went to a demonstration
from a wonder kid named Howard Armstrong,
who had figured out how to make triode vacuum tubes,
create smooth radio waves
and amplify signals
up to 5,000 times more powerfully than before.
Sarnoff then invited Armstrong to demonstrate his device
at one of the Marconi Companies tower
and they spent 13 hours straight in a frigid shack
receiving signals from around the world.
Years later Sarnoff said,
"Whatever chills the air produced
were more than extinguished by the warmth of the thrill
which came to me at hearing for the first time
signals from across the Atlantic and across the Pacific".
Sarnoff tried to get the Marconi company to buy the patent
but they refused,
possibly because they were in (indistinct)
with the original inventor of the vacuum triode.
Sarnoff and Armstrong were disappointed
but they remained friends.
Two years later,
Sarnoff sent his boss a proposition.
"I have in mind a plan of development
which would make radio a "household utility"
in the same sense as the piano".
Nally was interested
but the higher ups thought it was too radical,
so that too came to nothing at the time.
In April of 1917,
America joined World War I,
and Sarnoff attempted to volunteer for the navy
but was denied
because his job was vital to the war effort
or, as Sarnoff thought, because of anti-Semitism.
Meanwhile, Howard Armstrong volunteered for the army
and was stationed in Paris, working on radio systems.
In Europe, Armstrong heard that
the Germans were using very high frequency waves,
but he didn't know how they were doing it,
as radio waves at that time,
did not work well above about 500 KHz.
Months later,
Armstrong was watching a night bombing raid in Paris.
He started thinking about the high frequency radio waves
produced by the motor ignition systems in the airplanes.
He wondered what would happen
if he combined them with the high frequency radio waves,
he could create in a receiver.
Suddenly, he had a radical solution
to the high frequency problem.
He knew that if two waves were combined
with slightly different frequencies,
then they produce the beat frequency.
You might have heard this phenomenon
if you've ever tried to tune a guitar without a tuner.
When you make two notes
that are at slightly different frequencies,
the result is a whomp whomp sound.
(whomp sound).
Armstrong realized that he could use this method
to make lower frequency waves
out of high frequency ones.
This was an actually not a completely new idea.
In 1905, a man named Reginald Fessenden
had patented his plan
to mix two signals so that the beat frequency was audible
and you could hear it on headphones.
Fessenden called it the heterodyne method
hetero, for two different,
dyne, for force.
Armstrong's insight was to combine signals
to produce radio waves that were manageable
but were still above hearing, or super sonic.
For that reason,
Armstrong called his idea the superheterodyne method.
And if you look into a schematic of it,
the basic idea is still the same.
You take a radio signal
and mix it with another signal
at a slightly different frequency,
producing the beat frequency
or intermediate frequency.
One of the advantages of the superheterodyne method
is that you can set it up
so that the intermediate frequency is constant
for any radio station you're listening to.
That way, the bulk of the equipment
is optimized to amplify that set frequency.
Armstrong built a working system
but it was too big and complicated for commercial use.
When the war ended in 1919,
Sarnoff's boss created a brand new company
with the idea of keeping all radio communication
in the hands of Americans.
For this reason, he called it
the Radio Company of America or RCA.
After a few years of wrangling,
RCA managed to have the patents
for basically everything to do with Radio,
over 2,000 patents.
Now Sarnoff could implement his scheme
to make radio a "household utility".
Meanwhile, between 1920 and 1922,
Armstrong received a whopping $735,000 in cash
and 60,000 shares of RCA stock,
making Armstrong RCA's biggest stockholder for his patents,
even the ones that didn't end up working out that well.
In addition, he also met
Sarnoff's secretary, Marion MacInnis, and fell in love.
In February of 1923,
Armstrong demonstrated
a simplified version
of his superheterodyne method for Sarnoff.
And Sarnoff scrapped millions of dollars of past orders
to make all of their radio equipment superheterodyne.
Still, this original plan
wasn't workable for mass produced systems.
Finally, the exacerbated Sarnoff said,
"What do I do?"
To which Marion said, "Why don't you call in Armstrong?"
Armstrong swooped in,
and with an army friend of his named Harry Houke,
saved the day.
By February of 1924,
RCA finally had its superheterodyne receivers
including the Radiola AR-812,
the "Rolls Royce of Radio"
which only needed three controls.
So how did the Radiola's controls work?
Well, in the early radios,
they used an adjustable capacitor,
where if you turned a knob,
more or less metal was put in parallel with each other,
which changed how much charge it can hold.
If a capacitor is discharged through a coil,
it vibrates at a certain frequency.
So by adjusting the capacitor,
you're changing the frequency of oscillation.
The first knob changed the capacitance of one capacitor,
which controlled the frequency of resonance
with the antenna.
In other words,
it controlled which frequency radio station
you were listening to.
The second knob controlled the frequency of the oscillations
that you were mixing with the incoming signal.
Once again, by adjusting a capacitor,
you would tune this until the beat frequency
or the intermediate frequency
was at the note
that the rest of the electronics was maximized for,
around 45 kHz.
The final knob was for the volume.
The Radiola used 6 vacuum triodes
and you adjusted the volume
by changing the resistance of a resistor next to a battery
that was heating the filament of the triodes.
The idea is, if you lower the resistance,
then the current through the filament increases
which heats the filament more.
As the filament gets hotter
more electrons can flow from the filament,
which increases the volume in the headphones.
Whew! After that, RCA had basically a monopoly on radio.
Sarnoff then formed
America's first broadcasting network, NBC,
one of the big five studios, RKO pictures,
and reined as the president of RCA
and boss of radio, movie, and the television world
until he retired in 1970 when he was 79 yrs old.
Meanwhile, back in 1924,
Howard Armstrong was rewarded
with another 20,000 shares of RCA stock
and Armstrong wrote Harry Houke
a personal check for $100,000.
To give you a sense of how much that was,
the average income in 1924 was $3,400.
Howard Armstrong celebrated
by climbing the top of RCA's 400 foot tower
and doing insane acrobatics to show (indistinct).
Sarnoff crossly wrote,
"If you have made up your mind
that this mundane universe of ours
is not a suitable place for you to be spending your time in,
I don't wanna quarrel with your decision,
but keep away from the property of the Radio Corporation."
Armstrong didn't care,
he was wealthy, famous, and most importantly,
Marion had finally agreed to marry him.
Armstrong was literally and figuratively
on top of the world.
Which meant there was only one way to go.
And unfortunately, Sarnoff was a large part of his downfall.
How Armstrong invented FM radio,
and was so amazing
that it destroyed his relationship with Sarnoff
and eventually his life,
is next time on the Secret History of Electricity.
♪ Electricity electricity ♪
Thanks for watching my video.
Please remember to give it a thumbs up,
also remember to subscribe,
and if you have any questions,
please put them on the bottom
and I'll try my best to answer them.
Also, if you're interested in more history,
about Howard Armstrong, Reginald Fessenden or Marconi,
please look on the end of the video
and I will include links.
Okay, have a nice day.
(soft tonic music)