June 1963 Popular Electronics
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While a bit far-fetched, this Carl & Jerry saga has the
two amateur radio hobbyists cum detectives applying their knowledge
of standing waves and an invention called
SNARE (Signal Net for Actuating Radio-sensitive Explosives,
by Irwin Ehlmann) to thwart an assassination attempt on a visiting
foreign dignitary. The choice by author John T. Frye of
a halo antenna on their mobile shortwave rig was probably no
coincidence given the guardian angel role it played in the adventure.
Carl & Jerry: Elementary Induction
By John T. Frye W9EGV
A Carl and Jerry Adventure in Electronics
" ... see if you don't make out a pair of wires going down
over the edge of the bluff ... "
The dew-washed June morning found Carl and Jerry testing
out their super-duper Field Day radio station atop a high limestone
bluff overlooking the river. Radio amateurs, on their annual
Field Day, familiarize themselves with the operation of emergency
radio equipment by competing to see which station can make the
most contacts during a 24-hour period. The score made is multiplied
substantially if the station is set up out in the "field" with
no connection to commercial power lines.
Determined to run up a high score, the boys had two five-hundred-watt
transmitters in the back of a station wagon borrowed from Carl's
parents. One was a band-switching job that could be operated
on all amateur bands from 75 through 10 meters. The other transmitter
was for six meters only.
An all-band trap antenna had been swung between two trees
for use with the band-switching rig. On Field Day, there would
be a rotatable beam for the six-meter station, but today the
boys intended to test the station out with a halo-type antenna
mounted on the rear bumper of the station wagon.
A two-wheel trailer containing a husky 10-kw. gasoline-powered
a.c. generator was hitched to the rear bumper of the station
wagon. It was puttering away while Jerry hunkered down inside
the station wagon connecting antennas, mikes, switches, relays,
etc. Carl was outside playing around with a powerful, tripod-mounted,
prism-type spotting telescope he had recently acquired.
Carl looked back along the steep, narrow, twisting dirt path
up which the station wagon had clawed its way from the paved
road running alongside the river down below. Then he raised
the front of the telescope and looked across the river at the
road running along the top of the bluff on that side.
"Hey, wonder why the law is so busy across the river," he
called to Jerry. "I can see the sheriff's car and two state
police cars cruising along over there."
"Didn't you look at last night's paper?" Jerry asked. "The
president of a South American country is going to inspect a
typical Midwest corn farm about two miles west of here on the
other side of the river at ten this morning. It's feared political
enemies from his country may try to kill him and so create an
international incident. Naturally, our government intends to
do everything possible to prevent anything of this nature. That's
undoubtedly why the police are checking the route so carefully."
"So that's it," Carl muttered, swinging the telescope to
the right and peering through a thin screen of bushes at the
top of another limestone ridge a half-mile away on his side
of the river. "Boy, this 'scope is really a honey," he remarked.
"There are a couple of guys sitting over there on that other
ridge, and I can see the buttons on their shirts. Wonder what
they're doing. They seem to be just sitting there with a kind
of funny-looking gasoline can between them. One of them keeps
watching the road across the river through a pair of binoculars."
To Carl and Jerry Fans:
I'd like to answer personally all the wonderful cards,
letters, and messages wishing me a quick recovery from
my recent illness; but, as I'm sure you understand,
that is virtually impossible; so I'm taking this means
to thank all of you who sent them.
The good wishes and prayers mentioned in so many
of these heart-warming messages must certainly have
"worked," for I have recovered completely.
Writing future Carl and Jerry stories will be even
more fun now that I know so many of you readers enjoy
them. Thanks a million!
John T. Frye
Note: This greeting was published in response to
a notice of Mr. Frye's illness that appeared in the
February 1963 edition of Popular Electronics.
Jerry slid out the back of the station wagon and came over
for a look. "That's no gasoline can," he exclaimed; "it's a
blasting-cap detonator! Look closely and see if you don't make
out a pair of wires going from it down over the edge of the
bluff to the road below and then across the road through some
treetops and on down toward the river."
"Yeah," Carl agreed, "and those wires keep right on going
across the river and up the bluff to that little culvert under
the road over there. So help me: those jokers must be planning
on blowing up the president when he crosses the culvert! We
better go tell the police."
"There's no time," Jerry objected, looking at his watch.
"The president's car should be along any minute now, and there
isn't a farmhouse either way for two miles. By the time we got
to a telephone it would be too late. I'm going to try to raise
someone on seventy-five meters and have them call the police!"
The boys scrambled into the station wagon and fired up the bandswitching
transmitter. Jerry pushed the button on the mike while he watched
the meters on the front of the transmitter. A worried frown
creased his forehead as he quickly rechecked the knob settings.
"Something's wrong," Jerry said.
"We're getting no drive to the final." Gingerly he raised
the lid of the exciter and peered inside. "The driver tube is
stone cold," he announced, "and we don't have a spare. The filament
must have been jarred in two by the rough ride up here."
"Try the six-meter rig," Carl suggested, glancing nervously
across at the empty highway on the other side of the river.
Jerry quickly put the high-frequency transmitter into operation
and desperately called "QRRR," the amateur emergency distress
signal. No sign of an answer was heard in the receiver.
Twice more he put out the distress call, with absolutely
no results. "It's no use," he said as he snapped off the receiver
and started unscrewing the coax cable antenna lead from the
other transmitter. "No one monitors six meters around here this
time of day. Our only chance is to get down there to where the
wires cross the road and try to break them before the president
"You drive," he suggested hurriedly as he threw the end of
the cable out the rear of the car, "and don't spare the horses."
"Hadn't we better uncouple the generator?" Carl asked as
he climbed into the driver's seat.
"No time for that; get going!" Jerry urged.
The drive up that steep zigzagging path had been spine-tingling,
but it was nothing compared to the ride down. Carl sent the
station wagon hurtling along the narrow, twisting path while
behind, the heavy generator, still humming away, bumped and
jolted and careened first over on one wheel and then on the
other, threatening to overturn at any instant. Somehow, though,
they finally reached the black-topped road that paralleled the
Just as Carl made a tire-screeching right turn onto the road,
Jerry glanced up at the top of the bluff directly across the
river and uttered an exclamation.
"There's the motorcade now," he shouted. "See if you can
gain a good lead on them before we reach the wires."
Carl tried. The accelerator was clear to the floor as the
station wagon and the heavy trailer raced along the winding
black-topped road, but the cavalcade across the river was also
traveling at a fast clip on a stretch of highway that ran perfectly
straight. As the station wagon neared the point where the wires
should run across the road, it was obvious to both boys the
scant 200-yard lead they had over the state police car leading
the motorcade was not enough to give them time to locate the
detonating wires, stop the car, get to a point where they could
reach the wires, and cut them.
Carl kept taking quick upward glances as he let the car slow
down. "There they are!" he said, pointing to where two inconspicuous
wires crossed the road from one treetop to another. A glance
was all that was needed to convince the boys that the wires
were far too high to be reached even if they stood on top of
the station wagon.
"Stop the car with the back bumper directly under the wires,"
Jerry called to Carl.
Carl slammed on the brakes, and the wagon came to a lurching
stop with the halo antenna squarely underneath the twin strands
of wire. Jerry threw full power into the six-meter transmitter,
and he and Carl stared in sickening fascination at the rapidly
closing gap between the motorcade and the mined culvert across
Suddenly there was a muffled roar, and a fountain of dust
and broken pieces of concrete erupted from the point where the
highway crossed the culvert. As the rocks and chunks of concrete
rained down into the river, causing splashes that reached almost
halfway across, the boys saw the entire cavalcade brake to a
halt a scant hundred yards from where the explosive had torn
a gaping trench clear across the highway.
The boys leaped from their car and looked upward at the point
where the wires disappeared over the top of the bluff above.
Two dark-skinned faces silhouetted against the blue sky stared
down at the boys and at a car parked at the side of the road
not far away from the station wagon. After a few frozen seconds,
the faces disappeared.
"That must be their getaway car," Carl exclaimed. "They probably
will be afraid to try to get to it now with us here, but just
to make sure we'd better take the rotor out of their distributor.
They must really feel pretty sick about getting impatient and
blowing up the culvert too soon."
"They didn't blow up the culvert; we did," Jerry corrected
"We what? You must have had your little gray cells jarred
by that explosion. How could we have set off the dynamite, or
whatever it was ?"
"We did it with r.f. from our six-meter transmitter. Radio
frequency currents from the halo antenna induced similar currents
in the wires leading to the dynamite caps. Standing waves on
these wires produced heating in the caps and detonated them."
"So that's why you wanted "me to stop with the back of the
car directly under the wires! What ever made you think of detonating
the caps with r.f.?"
"Well, we both know it's dangerous to use transmitting equipment
in an area where blasting is going on. We've seen highway signs
warning against that sort of thing. And then I was reading a
story recently about a patent that had been taken out to eliminate
explosions on airplanes caused by bombs concealed in baggage.
The apparatus is called SNARE, or Signal Net for Actuating Radio-sensitive
Explosives. A man by the name of Irwin Ehlmann of Hatboro, Pennsylvania,
is the inventor.
"The device consists of a 30-foot bombproof chamber with
a conveyor belt running through it. Baggage on this belt is
exposed to strong radio frequency waves of different wavelengths.
These radio frequency waves will detonate any caps concealed
in the baggage and so set off the explosive.
"When I realized we couldn't reach the wires in time, all
this flashed through my mind. There wasn't anything else we
could do; so it seemed worth a try-"
Jerry was interrupted by a wailing siren, and in a few seconds
a state police car came to a stop behind the generator which
was still sitting in the middle of the road. The police across
the river had seen the wires leading across the water, and they
had dispatched a cruiser to investigate. The officer, "Doc"
Watson, was known to the boys, and they quickly explained to
him what had happened. He relayed the information over his radio,
and a net was quickly thrown up around the area.
"Those fellows will be picked up shortly," officer Watson
prophesied. "They don't stand a ghost of a chance of getting
away on foot.
"We all certainly owe you two a big debt of gratitude," he
said then, "but I must admit I still can't understand how you
set off that dynamite clear across the river without even touching
"Elementary induction, my dear Dr. Watson, elementary induction!"
Carl replied with a teasing grin.
Carl & Jerry: Their Complete Adventures is now available. "From 1954 through 1964,
Popular Electronics published 119 adventures of Carl and Jerry, two teen boys with a passion for electronics and a knack
for getting into and out of trouble with haywire lashups built in Jerry's basement. Better still, the boys explained how
it all worked, and in doing so, launched countless young people into careers in science and technology. Now, for the first
time ever, the full run of Carl and Jerry yarns by John T. Frye are available again, in five authorized anthologies that
include the full text and all illustrations."
Carl & Jerry Episodes on RF Cafe
- Carl & Jerry: Anchors Aweigh, July 1956
- Bosco Has His Day, August 1956
- The Hand of Selene, November 1960
- Feedback, May 1956
- Abetting or Not?, October 1956
- Electronic Beach Buggy, September
- Extra Sensory Perception, December
- Trapped in a Chimney, January 1956
- Command Performance, November 1958
- Extracurricular Education, July
- Treachery of Judas, July 1961
- The Sucker, May 1963
- Stereotaped New Year, January 1963
- The Snow Machine, December 1960
- Extracurricular Education, July
- Slow Motion for Quick Action,
- Sonar Sleuthing, August 1963
- TV Antennas, August 1955
- Succoring a Soroban, March 1963
- "All's Fair --", September 1963
- Operation Worm Warming, May 1961
- The Crazy Clock Caper, October 1960
- Two Detectors, February 1955
- Tussle with a Tachometer, July 1960
- Therry and the Pirates, April 1961
- The Sparkling Light, May 1962
- Pure Research Rewarded, June 1962
- A Hot Idea, March 1960
- The Hot Dog Case, December 1954
- A New Company is Launched, October 1956
- Under the Mistletoe, December 1958
- Electronic Eraser, August 1962
- Blubber Banisher, July 1959
- "BBI", May 1959
- Ultrasonic Sound Waves, July 1955
- The River Sniffer, July 1962
- Ham Radio, April 1955
- El Torero Electronico, April 1960
- Wired Wireless, January 1962
- Electronic Shadow, September 1957
- Elementary Induction, June 1963
- He Went That-a-Way, March1959
- Electronic Detective, February 1958
- Aiding an Instinct, December 1962
Posted May 7, 2014