the continuing saga of Carl and Jerry, our two young electronics
hobbyists visit a college radio station where the manager gives
a tour while explaining the technical aspects of the equipment.
RF bridges, hybrid junctions, oscillator coils and plate-tank pi-networks,
cue amplifiers, limiter amplifiers, patch board, power supplies,
and a lot of other terms that cause RF Cafe visitors to salivate
are woven into the story. Carl and Jerry are surprised to learn
that the transmitter output power is high enough that dormitory
residents can pick up the signal with "only a pair of earphones
clipped across a 1N34 diode" as well as with a standard AM radio.
In fact, that's the whole point of the story because the broadcast
is not over the air, but via the campus' AC electrical system -
hence, "wired wireless."
January 1962 Popular Electronics
[Table of Contents]People old and young enjoy waxing nostalgic about
and learning some of the history of early electronics. Popular Electronics was published from October 1954 through April 1985. All copyrights are hereby acknowledged.
get a load of Carl's Farside™-styled glasses. That was before they
went out of style... way out of style.
See all articles from
Carl and Jerry: Wired Wireless
John T. Frye
Mind telling me why we're climbing
to the sixth floor of Gary Hall?" Jerry puffed as he followed his
athletic chum, Carl, up the stairs.
chief technical and maintenance engineer of WCCR, master station
of the carrier-current campus radio network, wants to see us. And
we've been itching to see the station. Need I say more?" Carl asked
as he pushed open the door at the top of the stairs.
A stocky, dark-complexioned young man rose from a chair across the
large room and came to meet them. "You must be Jerry Bishop; and
you, Carl Anderson," he said, holding out his hand. "I'm Jimmy Young.
Thanks for coming. Want to take a quick look around the station
before we get down to the little matter I have in mind?"
"Yeah!" Carl and Jerry chorused.
A grin spread
over Jimmy's face as he brushed back his dark hair with his hand.
"Okay, but first you gotta suffer through my two-dollar lecture,"
"You're now standing in the office and
lounge of WCCR, master station of what we think is the oldest and
largest carrier-current campus radio network in the world. There
are four other stations in the net: WMRH in H1 Residence Hall, WHRC
in H2, KMRX in H3, and WCTS in the State Street Courts. As soon
as it's completed, we expect to add a sixth station, WGRC, in the
Women's Residence Hall.
"Each station," he continued,
"operates on a selected crystal-controlled frequency somewhere between
570 and 660 kilocycles. The r.f. from the transmitter is fed into
the power circuits of the particular residence unit so that any
radio inside the building can pick up the program but no signal
can be heard outside.
station is self-sufficient; it's constructed, maintained, and operated
by students housed in that building, and it furnishes programs for
the residents of that one housing unit.
"At the same
time, each satellite station is connected to the patch board of
this master control station by a closed telephone loop so we can
feed programs to it or it can furnish programs for the network.
All five stations take turns furnishing network programs. A simplex
telephone circuit in connection with each telephone loop permits
exchanging information about programing, etc.
go into Studio A, our master control room."
The boys followed
him through the door, and the first thing that caught their eyes
was a couple of standard six-foot racks filled with electronic equipment.
A control console, two turntables, tape recorders, an AM-FM tuner,
and other assorted pieces of equipment were arranged for maximum
"I'll talk about WCCR," Jimmy announced,
"for it's the oldest and most sophisticated station, and it's the
one I know the most about; but the basic transmitters of the other
stations are similar. This is the station for Gary Hall, often
called the Men's Quadrangle because it actually consists of six
residence halls arranged in a rectangle. Power circuits for the
Quadrangle are fed from six different power boxes furnishing 220
volts single phase a.c.; so we have to feed our r.f. into each of
"Must take lots of r.f.," Carl said. "How
many kilowatts do you run ?"
"We use two separate transmitters
here at WCCR so we can transmit the same program on two different
frequencies and provide stereo reception, but each transmitter inputs
only about 30 watts! In fact, the transmitters are revamped Heathkit
DX-35's. We put in new oscillator coils and plate-tank pi-networks
designed to have a satisfactory Q at a low, broadcast-band frequency,
and to feed a 72-ohm coax line. These transmitters are plate-modulated
in each case by a pair of 5881's in Class AB driven by a 12AX7 as
a combination amplifier and phase-inverter."
the rest of that stuff?" Carl asked, waving at the big racks.
"Preamplifiers, monitor amplifiers, cue amplifiers, limiter
amplifiers, patch board, power supplies, and other little goodies
needed to transmit really high quality programs and to serve as
a master control station. Our preamps and line amps are flat from
10 cycles to 25,000 cycles, but we restrict the high end to 9000
cycles and boost the bass before feeding the signal to the modulator.
We do this to prevent splatter and to compensate for the poor low-frequency
response of the small radios used to receive us."
you run two different r.f. signals into your single 'antenna,' the
power lines, when you're operating stereo," Jerry commented. "How
do you prevent interaction between the two transmitters ?"
"We use what we call a hybrid junction. This is similar to the
diplexer unit a TV station employs to feed both the audio and video
transmitters into the same antenna. Actually, it's a form of r.f.
bridge that permits each transmitter to feed the line but prevents
r.f. from backing up into the other transmitter."
you actually couple into the power boxes?" Carl wanted to know at
"We use an r.f. transformer for each box. The
primary is tapped so we can hook several in parallel and still get
a proper impedance for our 72-ohm line. Each side of the secondary
goes through an 0.0005 blocking capacitor and a 10-ohm, 5-watt resistor
to one side of the 220-volt line. The capacitor, of course, keeps
the 60-cycle a.c. out of the transformer winding.
found that the impedance from one side of the power line to ground
varies between 1/4 and 1/2 ohm at our carrier frequency as different
devices in the building are switched on or off. Naturally a two-to-one
change in load impedance would badly upset any established match;
but when the resistor is inserted, the impedance seen by half the
transformer secondary can only vary between 5 1/4 and 5 1/2 ohms,
and that can be tolerated. Lots of power is lost in the resistors,
but we've enough left."
"Can you pick up the program on
a transistor radio in one of the rooms, or does the radio have to
be plugged into the line?" Carl asked.
"You know you can
pick it up on any kind of radio; so stop pulling my leg! In fact,
you can receive it with only a pair of earphones clipped across
a 1N34 diode. Remember, you're practically sitting on the antenna,
for every wire in the building is radiating r.f. for a short distance."
"What hours do you operate?" Jerry questioned.
on twenty-four hours a day, seven days a week. We start with some
rock-and-roll wake-up music around 7 :30 a.m. During the rest of
the morning we feature good-to-study-by music, not too distracting,
and a special lunch program of music is on during the noon hour.
In the afternoon we play 20 or 30 of the top records. Dinner music
is on from 5:30 to 6:30, and after dinner we have more pop tunes
- but no rock-and-roll. From 9 until 11 it's semi-classical; from
11 to 12 we have an hour of the very best classical music. Then
we switch over to the tuner bringing in one of the clear channel
broadcast stations that operate all night, and we ride that until
you get permission to rebroadcast their programs?"
although strictly speaking we wouldn't have to. We're not rebroadcasting.
Our wired-wireless is actually just a big p.a. system."
"Do you do any live shows?" Jerry asked.
"Oh, sure. We do
interviews in our studios here, and we do remote pickups from all
over the campus. We may do a poolside program from the Co-Rec Gym
during a swimming meet; we may broadcast a baseball game; or we
may work remote from a record hop, or dance, or any other spot calculated
to stir up interest among our listeners. Our patch board is connected
to that of the university broadcast station by a permanent loop,
and sometimes they let us use their remote lines when we're doing
a remote show. But let's take a look at the rest of the station.
"Here, next door, is Studio C, which is just an announcing
studio. Studio B, over there to the left, has a console and turntables,
and is set up as a control room for monophonic work. On down the
hall is our record library - we have 5000 45's and about 2000 LP's
in there, and among the latter are many of the finest classical
records. We're starting to stock up on stereophonic records and
tapes now, for the fellows seem to like our stereo programs."
"Where do you get the money for all this?" Carl asked bluntly.
"As you know," Jimmy replied, "each residence hall has its
own social organization or club. You automatically join this club
when you take up residence and are charged a membership fee of $15
a year to pay for social activities, music groups, camera club,
residence-hall radio station, etc. Each station prepares a budget
each year and receives a certain amount of the club dues to pay
for records, maintenance, and new equipment."
must be soundproofed," Carl remarked as he watched the lips of an
announcer in Studio C moving but heard no sound.
The walls are double-studded, and each wall contains two layers
of acoustical wall tile, two layers of Celotex, and two 2" layers
of star foam. The glass partition windows have double panes set
in rubber so they can't conduct sound. Over here, next to the stairs,
is our lab and workshop where we build and test our equipment. You
see we have the usual meters, signal generators, and 'scope ...
"Say, fellows, I'd like to go into more detail, but I'm
running out of time. Suppose we go over to the desk and I tell you
why I had you come up."
They sat down at the desk, and Jimmy
peered at them from beneath his heavy brows as he toyed with a set
of keys fastened to his belt with a silver chain.
joker always tries to get into the act, and we have one here at
Gary Hall," he said with a sigh. "For the past week someone in the
southwest wing has been jamming our programs. He sits on the frequency,
plays records, makes sarcastic remarks about our programs, and tries
to get the listeners to tune to another frequency where he says
he is going to put on a real program.
"We thought he'd soon
get tired and quit this foolishness, but apparently he's not going
to; so we've got to find him and put a stop to it. Too many students
are complaining that they're not getting much satisfaction out of
the money they've paid for carrier-current entertainment."
"How do you know the guy is in the southwest wing?" Carl quizzed.
"That's the only place his signal is heard. Signals won't
feed back through the r.f. transformers from one power box to the
"Where do we come in?" Jerry asked. "We need some
outsiders to help track the wildcatter down. Members of the WCCR
staff are too well known here at Gary Hall; as soon as one of us
steps into that southwest wing, the station goes off the air. But
I hear you two are pretty good electronic technicians. Will you
"Sure, but how can we?" Carl wanted to know.
Jimmy opened a drawer and took out a small transistorized tape
recorder. A shielded cord ran from the microphone jack to a little
black metal box with a small coil sticking out one end.
"This is a ferrite-rod antenna coil tuned to the frequency of the
wildcat station," Jimmy explained. "A crystal diode inside the box
detects the signal picked up by the coil and feeds it to the recorder
amplifier. With the monitoring earphone of the recorder, you can
hear anything picked up by this r.f. probe and being recorded.
"The wildcatter can't be running much power; so his signal
should fall off rapidly on this insensitive detector as the distance
from the room where he is feeding the signal into the line increases.
I want you two to use this to spot his room; then call me, and the
hall counselor and I will take it from there."
"In about ten minutes, if you will. He comes
on every evening at four, and it's nearly that now. We'll play piano
music from four until four-fifteen so you can tell his station from
ours. Then I'll fake a station breakdown so you'll have his signal
in the clear. Okay?"
Before they quite knew what they were
doing, Carl and Jerry found themselves walking down the hall on
the second floor of the west wing of the Quadrangle. They tried
to saunter along very non-chalantly, but they felt as conspicuous
as a couple of skunks at a perfume manufacturers' convention. The
recorder was humming away in Jerry's overcoat pocket, and his turned-up
coat collar concealed the earphone.
"I'm hearing both stations,"
he muttered to Carl. "The joker's rock-and-roll is beginning to
drown out the piano. We must be getting close. He's stronger on
this side of the hall. Oh, oh! There goes the piano music off. The
wildcat station is really getting loud now, but keep walking. Now
it's beginning to fall off. Let's turn around.
it's the loudest. He's talking now. Pretend to show me something
in that math book while I take this earphone out of my ear. Say!
I can hear him talking through the ventilator at the same time I
hear him on the earphone. This is the room. Call Jimmy while I keep
the recorder going."
Carl called from a telephone booth
in the hall, and in only a few minutes Jimmy came dashing up with
another young man. They took the tape recorder, listened to the
sounds coming from the ventilator, and then knocked at the door.
Carl and Jerry walked on down the hall as the door finally opened
and two flustered-looking youths let Jimmy and the counselor in.
Fifteen minutes later, the door opened again, and Jimmy
and the counselor emerged. They were carrying a small 45-rpm record
player and what the two boys recognized as being a wireless phono-oscillator.
"Well, fellows, there goes our wildcat radio station," Jimmy
said as he joined them and the three started for the stairs. "When
they heard the tape recording, they broke down and confessed. The
equipment has been confiscated, and I'm pretty sure we won't have
any more of that sort of thing. And I certainly want to thank you
for helping. I've got to scamper back and put the station on the
air again now, but I'll see you around."
Big lazy snowflakes
started drifting down as Carl and Jerry walked briskly toward H3
in the gathering darkness. The patterns of lighted windows in the
residence halls looked warm and friendly.
"Say, Carl," Jerry
suddenly exclaimed, "I like being part of a school where the students
can design and build and maintain and operate an elaborate radio
network like that in their spare time-especially when we both know
how precious little spare time they have."
"Yeah, me too,"
Carl agreed. "I think we're in the right place."
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
|- Electronic Beach Buggy
- September 1956
- Extra Sensory Perception
- December 1956
- Trapped in a Chimney
- January 1956
- Command Performance
- November 1958
Education, July 1963
- Treachery of Judas,
- 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
- 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
Hot Idea, March 1960
- The Hot Dog
Case, December 1954
- A New Company
is Launched, October 1956
the Mistletoe, December 1958
Eraser, August 1962
- Blubber Banisher,
- "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 22, 2012