January 1962 Popular Electronics
Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
published October 1954 - April 1985. All copyrights are hereby acknowledged.
In 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."
BTW, get a load of Carl's Farside™-styled glasses. That was
before they went out of style... way out of style.
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.
"Jimmy Young, 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.
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," he warned.
"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
Each 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,
"Now, let's 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 convenience.
"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 these boxes."
"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."
"Then what's 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 say 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."
"How do you actually couple into the power boxes?" Carl wanted
to know at this point.
"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.
"We've 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
"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.
"We're 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 morning."
"Do you get permission to rebroadcast their programs?"
"Yes, although strictly speaking we wouldn't have to. We're
not rebroadcasting. Our wired-wireless is actually just a big
"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
"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."
"Those studios must be soundproofed," Carl remarked as he
watched the lips of an announcer in Studio C moving but heard
"They are. 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.
"Some 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
"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
"That's the only place his signal is heard. Signals won't
feed back through the r.f. transformers from one power box to
"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
"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
"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
"When ?" Carl asked.
"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.
"Right here 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
"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
Carl & Jerry: Their Complete Adventures is now available. "From
1954 through 1964, Popular Electronics published 119 adventures of Carl Anderson and Jerry Bishop, 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 Eraser,
- Electronic Trap, March
- Geniuses at Work, June
- Eeeeelectricity!, November
- Anchors Aweigh, July
- Bosco Has His Day,
- The Hand of Selene,
- Feedback, May 1956
- Abetting or Not?, October
- Electronic Beach
Buggy, September 1956
- Extra Sensory
Perception, December 1956
- Trapped in a Chimney,
- Command Performance,
Education, July 1963
- Treachery of Judas, July
- The Sucker, May 1963
- Stereotaped New
Year, January 1963
- The Snow Machine, December
Education, July 1963
- Slow Motion for
Quick Action, April 1963
- Sonar Sleuthing, August
- TV Antennas, August 1955
- Succoring a Soroban,
- "All's Fair --", September
- Operation Worm Warming,
- The Blubber Banisher,
- The Sparkling Light, May
- Pure Research Rewarded,
- A Hot Idea, March 1960
- The Hot Dog Case, December
- A New Company is Launched,
- Under the Mistletoe,
- Electronic Eraser,
- "BBI", May 1959
- Ultrasonic Sound Waves,
- The River Sniffer, July
- Ham Radio, April 1955
- El Torero Electronico,
- Wired Wireless, January
- Electronic Shadow,
- Elementary Induction,
- He Went That-a-Way,
- Electronic Detective,
- Aiding an Instinct,
- Two Detectors, February
- Tussle with a Tachometer,
- Therry and the Pirates,
- The Crazy Clock Caper,
Posted May 22, 2012