RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while typing up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
All trademarks, copyrights, patents, and other rights of ownership to images
and text used on the RF Cafe website are hereby acknowledged.
Wax nostalgic about and learn from the history of early
electronics. See articles from Radio & Television News, published 1919-1959. All copyrights hereby
AT&T "Reach out and touch someone" commercial, c1979
Before there was the World Wide Web (aka the Internet) and unlimited cellphone
calling plans, personal communications over any distance for most people was limited
to local telephone calling areas. Long distance calling rates were high enough to
prevent casual calling of family, friends, and businesses in the U.S. Overseas call
rates were extremely prohibitive. The price to "Reach out and touch someone" could
set you back 10¢/minute or more. Even today, an old-fashioned landline plan
AT&T can cost you $3.50/minute to the UK, $4.50/minute to Japan, and $5.00/minute
to China. Depending on where you lived, calling someone in the next neighborhood
over could be a long distance call, while calling 50 miles in the other direction
would be considered local. Toll-free "800" long distance numbers were implemented
to encourage people to make contact with businesses without incurring additional
charges. Late night TV shows were famous for using 800 numbers to
into buying Ronco gadgets and
term life insurance policies. Radio was the primary medium for receiving communications
from far away at no cost other than equipment procurement. CB radio enabled two-way
communications up to fifty miles or so without the need for a special license, and
of course a Ham licensee could span the globe. If you were satisfied with merely
listening, shortwave radios facilitated the "magic" of hearing broadcasts from around
the world. Under favorable atmospheric conditions, particularly at night, even a
cheap AM/FM radio could pick up stations half a continent away. What was considered
annoying interference to most listeners was big game for "DX" hunters. "DX" is Ham
shorthand for "long distance." This 1951 installment of "Mac's Radio Shop" describes
what became a real thrill for TV owners: TV DX. The most enthusiastic tuners-in
went to extremes to pick up TX stations many states away, even if the picture and/or
sound quality was barely perceivable.™
Mac's Radio Service Shop: Television DX
By John T. Frye
Suddenly Barney, the "hired hand" of Mac's Radio Service Shop, slammed his solder
gun down on the bench and demanded of his boss: "Mac, what's so doggone funny? You've
been grinning like a television toothpaste commercial ever since you came back from
"Well," Mac explained, "by the time I got over to the Dutchman's this noon, all
of the counter stools were taken, and I had to sit in a booth. While I was eating
I couldn't help but overhear a hot antenna argument going on between a couple of
rabid TV fans in the booth behind me. Each guy was whooping it up for his antenna
system and using as evidence the distant television stations he pulled in during
that 'opening' we had around last
Decoration Day. Number One gave all the credit
to his battery of Yagis, while Number Two was convinced that his collinear array
was what enabled him to yank in the DX."
"And that's side-splittingly funny?" Barney questioned with arched eyebrows.
"In a way it is. I kept thinking how amusing it would be if I butted in and related
my own experience during that period. You will remember that I had just received
my new television chassis at the time and was waiting on a cabinet. However, I was
so eager to try out the high-fidelity amplifier on a couple of speakers I had at
home that I unpacked the chassis and set it on top of the shipping carton, cut a
twin-lead folded dipole roughly for the FM band and tossed it on a desk beside the
set, slid in a picture tube, and turned on the set.
"While I was adjusting the ion trap on the seventeen inch tube I was using, I
began to notice pictures on the screen. In the next couple of days, using that very
poor antenna, a yardstick for an antenna tower, without any booster of any sort,
and at this Northern Indiana location seventy miles from the nearest TV transmitter,
I logged Cuban stations on Channels 4 and 6; Miami and Jacksonville, Florida, stations
on 4; Chicago stations on 4, 5, 7, and 9; San Antonio, Texas, on 4 and Houston on
2; Milwaukee on 3; Louisville, Kentucky, on 5; and Indianapolis on 6. While there
was fading on some of the signals, both sound and picture were received in each
case with sufficient clarity to make identification easy and positive. In many cases,
the reception was perfect, without the slightest snow or noise."
"You don't suppose you could have stumbled on some kind of a super antenna in
that twin-lead job, do you?" Barney suggested hopefully.
"Not a chance," Mac replied with a chuckle. "Just to make sure, while Cuba was
rolling in on Channel 4, I took off the antenna and touched one of the terminals
with a screwdriver. 'Television Para Todo' came in almost as well as it had with
"No," he continued, "the point of the whole thing is that the antenna efficiency
seems to mean little during these periods of freak reception. In fact, a low antenna
may actually do a better job of picking up DX at such a time than will an antenna
mounted on top of a high tower. Either refraction or reflection causes the distant
signals to come in at pretty steep angles. The fact I could pick them up down in
the bottom of this river valley proves that. Signals from fairly close stations,
on the other hand, are usually not subject to so much distortion and continue to
be picked up better by more elevated antennas. As a result, an antenna that is really
up in the air picks up enough signal from a nearby station to interfere seriously
with a DX signal. A low antenna, on the other hand, gets the distant signal just
as strongly and without the interference from the close station."
"Then you think that when one of these freak DX periods start, the thing to do
is to start looking for faraway stations with a tuning knob in one hand and a folded
dipole in the other."
"It's worth a try, anyway," Mac said, smiling at the graphic picture Barney's
words evoked. "One thing in favor of such a system is that it allows you to switch
the antenna around much quicker than can be done with a rotating motor, and that
is a distinct advantage in this freak reception. The signals from Texas were received
best with the ends of my folded dipole pointing southwest and northeast - exactly
opposite to what a person would normally expect and indicating that the signal was
arriving by way of a most devious route. Furthermore, I counted as many as five
separate ghost images on the signal from Houston, some displaced from the main signal
by as far as three inches on the sixteen-inch screen. These ghosts kept moving back
and forth behind the main signal, and by turning the antenna, the chief signal
and one of the ghosts could sometimes be made to exchange roles. Often the signal
arrived in the form of closely-spaced waves of strength, and being able to whirl
the antenna about quickly during the peak of the wave permitted the best position
to be readily determined.
"Next time, though, I intend to use a special antenna I am making up just for
freak DXing," Mac continued. "It consists of a folded dipole with end sections that
telescope like the slide on a slide-trombone. A telescoping reflector is also used,
and both units are mounted so that the space between them can be easily varied without
up-setting their relative alignment. The element sections and the 'boom' are marked
so that the array can be quickly set up for any channel."
"Why go to all that trouble when you say the efficiency of the antenna is unimportant
when the DX signals are really piling in?"
"I'm not trying to increase the efficiency of the antenna," Mac explained. "What
I want is an antenna that is more one-directional to help in establishing more accurately
from just which direction the signal arrives; furthermore, by being able to tilt
the simple array, I hope to get a rough idea of the angles at which the signals
come in. Still another hoped-for advantage lies in the possibility of doing a better
job of separating several stations likely to be found occupying a single channel
during one of these unusual periods. You should have heard five different stations
battling it out on Channel 4 like cats fighting over a fishhead as I did last May
30th. That certainly makes you want something to help unscramble them."
"What produces DX like that, anyway?" Barney asked.
"I don't know," Mac readily admitted. "As a ham, you are, of course, familiar
with the theory that clouds of ionization frequently appear about fifty miles above
the earth and reflect back to earth high frequency signals that ordinarily would
never be returned. This 'Sporadic-E Ionization' as it is called may happen any time,
but it occurs most frequently during May, June, and July. That could explain my
experience except for one thing: that the signals from Texas seemed to be arriving
from either the southeast or northwest-exactly opposed to the southwest direction
in which Texas lies from here.
"Some of my friends," he went on slowly, "who know a lot more about such things
than I do, tell me that there is a growing theory that under certain favorable circumstances
a current of air under exactly the right conditions of moisture, barometric pressure,
and temperature can actually act as a huge waveguide and 'pipe' a high frequency
signal from one part of the earth to another. Maybe that is the answer. At least
it would permit the signal path to have a bend in it, as that one from Houston seemed
"At any rate," he continued, "I'm going to do all the 'observing' I can every
time one of these openings occurs. Hams have been doing that for years, but their
numbers are very small compared to the millions looking at TV screens every day.
If only a small percentage of these TV fans become interested in noting some of
the factors that affect abnormal DX signals, perhaps we can learn enough about them
to enable us to control these conditions."
"Could be," Barney agreed with a shrug. "Today's miracle is tomorrow's normal
occurrence. I keep remembering that at one time they gave the whole spectrum above
two hundred meters to the hams because they thought these frequencies would never
be of any practical value - the Indian givers! Next time the TV channels get hot,
just let Old Barney know, and he will be right in there waving a folded dipole alongside
Mac's Radio Service Shop Episodes on RF Cafe
This series of instructive stories was the brainchild of none other than John T.
Frye, creator of the Carl and Jerry series that ran in
Popular Electronics for many years. Mac's Radio Service Shop began life
in Radio & Television News
magazine (which itself started as simply Radio News), and then changed
its name to Mac's Service Shop after the magazine became Electronics
World. "Mac" is electronics repair shop owner Mac McGregor, and Barney
Jameson his his eager, if not somewhat naive, technician assistant. "Lessons" are
taught in story format with dialogs between Mac and Barney.