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 Prior to the International Geophysical Year
(aka IGY, which ended up running for a year and a half), spanning from July 1, 1957,
through December 31, 1958, not a lot was known about the upper atmosphere. May 1946,
when this article appeared in Popular Science magazine, was less than a
year after the end of World War II. During the war a lot was learned about
long distance wireless (radio) communications between and across continents and
ship to shore. Scientists theorized about the phenomenon of
charged particles at high altitudes which, being electrically conductive, could
reflect electromagnetic signals so that over the horizon signals could be exchanged.
Coincidence with sunspot activity and aurorae had already been established, but
more knowledge was needed. Rocket...
 This photo of Bell Telephone Labs' three
scientists, G.L. Pearson, D.M. Chapin, and C.S. Fuller, inventors
of the "Bell
Solar Battery," reminds me of the very familiar shot of John Bardeen, Walter
Brattain, and William Shockley huddled over their point contact transistor in December
of 1948. The "battery" terminology is an interesting choice since we normally
think of a battery as a charge storage device, but in fact a battery is fundamentally
a charge creation device. A secondary battery may be recharged by reversing the
depleted chemical (or other) process that generated the initial charge, but it first
created the potential via a basic charge separation process. What we today refer
to as a solar cell is a form of primary battery that is not rechargeable. Just as
some chemical batteries (cells) are reactivated by replenishing the electrolyte,
the solar cell is replenished by photons giving up their energy to the semiconductor
substrate...
 Here is the final installation of a 22 part
series entitled "The Saga of the Vacuum Tube," by Gerald Tyne, that appeared in
Radio News magazine in 1946. Part 1 was printed in March 1943. The collective
contents, which covered the development of the vacuum tube from its conception to
the end of World War I, could have been published as a stand-alone book. Author
Gerald F. J. Tyne presented the series to trace the development which
took place up to the end of World War I along a particular branch of the network
of roads which led to the modern radio tube. He traced the evolution from studies
of the interactions between heat and electricity as pursued by the early philosophers
and by the physicists who followed them (Lee de Forest, et al). These limitations
have been...
 There are many online
Fresnel Zone calculators.
Most do the basic calculation for the maximum radius of the Fresnel Zone for a given
frequency and separation between antennas. Some allow you to enter an obstacle's
distance from one of the antennas, and its height, then lets you know if the obstacle
falls within the Fresnel Zone. Very few plot the shape of the Fresnel Zone, and
even less include an obstacle positioned on the plot. Most rare are calculators
which take the curvature of the Earth into account. RF Cafe's new online Fresnel
Zone calculator handles all those parameters. Check it out...
 A few weeks ago I posted a two-part article
on the Taylor
super-modulation principle published in Radio & Television
News magazine in 1948. It was a newly announced technology at the time and
was written by its inventor, Robert Taylor. This piece entitled "Understanding Super-Modulation"
appeared a couple years later by another author, John McCord, where he describes
how it works , how to tune super-modulation circuits, and how it compares to other
modulation methods - all conveniently in "Ham language." Super-modulation is a form
of amplitude modulation (AM) that makes use of carrier and/or sideband suppression
to achieve greater efficiency. A panadaptor - aka pan-adapter, aka panadapter, aka
radio spectrum scope, aka panoramic adapter...
 It has been a long time since I heard this
saying: "Well, they always say that if you want to find out the best and easiest
way of doing something, just put a lazy man at the job." Mac McGregor offered that
line to his service shop technician Barney - in jest of course - when Barney explains
his million dollar invention idea for a
fool-proof vacuum tube tester that can be used by just about anyone.
Mac's Radio Service Shop creator John Frye often used the monthly techno-drama
to introduce some good ideas for new inventions and/or new methods for troubleshooting
problems. Somewhere along the line I think I have seen an advertisement for a tube
tester that used the automation concept dreamed up by Barney...
 I tend to be a traditionalist for most things,
but do not go out of my way to make trouble for other people who don't appreciate
the way things are and have been... as long as, per Thomas Jefferson, "It neither
picks my pocket nor breaks my leg." In other words, if your actions cause me no
financial or physical harm, I'm not likely to oppose your actions - unless they're
illegal. Many older Hams are greatly offended at the FCC for having removed the
Morse code requirement in 2005 for obtaining an amateur radio
operator's license. They see it as a way to separate the wheat from the chaff,
so to speak; that is to say, to maintain a barrier that keeps non-serious aspirants
from gaining entry into the ranks of the elite group...
 For more than a decade, I have been posting
these
Radio Service Data Sheets for radios and various other audio and
visual electronics sets that appeared in vintage electronics magazines. This one
for the Atwater Kent Model 649 all-wave, 9 metal tube, superheterodyne console radio
set was published in the November 1935 issue of Radio Craft. "All-Wave"
radios were popular at the time because they provided access to shortwave bands
so listeners could tune in foreign broadband stations - often with the rudimentary
built-in antenna. Short Wave Listening was actually a worldwide sport that had its
own cadre of enthusiastic participants, including a dedicated magazine entitled
Short Wave Listener...
 We read a lot about the
early
radar system that was in operation at Pearl Harbor in December 1941 when the
surprise attack by Japanese naval airplanes decimated the fleet with a 3-hour-long
raid beginning at around 8:00 on that sleepy Sunday morning. According to "The Untold
Pearl Harbor Radar Story," by C.P. West, the SCR-270B (Signal Corps radio #270,
rev B) radar system had a range of 250 miles at an altitude of 50,000 feet. Westinghouse
built the system in 1940 following a development contract issued by the Army Signal
Corps in 1936. Historical documents report of the three systems on the island, two
had been shut down and that with the remaining system, operators Joseph Lockard
and George Elliot detected a formation of aircraft about 137 miles out to sea. They
were told it was a squadron of B-17s and to not worry about it...
 This news bit from a 1951 issue of Radio-Electronics
magazine reports on the FCC's declaration of illegality the practice by some
FM broadcasting stations of providing a means for
blanking out commercials and station identification to entities
willing to pay for the special receivers and pay for a subscription. Nobody I have
ever known looks forward to enduring commercials on television or radio (or Internet
these days). The only way most of us could listen to music without interruption
was to by a record, tape, or CD. VHS tapes and DVDs provide some relief from commercials,
although even though you pay for them there are typically promotions for other movies
at the beginning. Commercials on radio and television (and now the Internet) have
consumed a larger part of each hour of programming with each passing year. The DVD
collections we have of 1960s and 1970s Prime Time TV shows average run times of
about 54-55 minutes...
 This is another example of a multi-part
article of which I happen to have discovered only one of installments - Part 9.
As is often the case, each article is pretty much stand-alone and does not require
that you have already seen the previous sections. In 1951, computers were still
mostly analog; digital circuits were just beginning to get serious research thanks
to the recent advent of solid state devices. Boolean algebra, truth tables, and
combinational logic were just beginning to be taught in engineering courses.
ENIAC (Electronic Numerical Integrator and Computer), first used
in 1945 at the end of World War II, was the world's first general purpose
digital computer, and its active elements were vacuum tubes - about 20,000 of them.
As you might expect, there was a lot of excitement in the electronics, scientific,
and finance world about digital computers that would be inexpensive enough that
individual corporations...
 Werbel Microwave, who since 2014 has designed and produced high
performance radio frequency components for defense, commercial, test and measurement
applications, is seeking an experienced manufacturers' representative firm to cover
the New England territory (CT, MA, ME, NH, RI, VT). Click thumbnail image for more
detail.
We're looking for a rep firm with:
- Established relationships in defense, aerospace, and commercial electronics
OEMs in the region.
- Complementary, non-competing RF/microwave lines.
- A motivated, technically knowledgeable sales team.
If your firm is the right fit, we'd love to connect. Reach out via DM or email
us at
sales@werbelmicrowave.com
 Moods are sometimes understandably less
than jovial and nerves might be shot after a challenging day at work. These
electronics-themed comics from a couple vintage Radio &
Television News magazines might help assuage your anxieties. The same goes
for those who are in Southern California and managed to arrive safely from a commute
on the notoriously unfriendly highways there. As with many of these old comics,
you have to be privy to the mindset of the day to fully appreciate the topic. TV
repair was big business and people were fascinated with the boob tube innovation
rapidly consuming the attention of domestic dwellers...
 I'm having a hard time writing this
with my eyes rolled back in my head. The last time I experienced this level of overwhelmedness
was probably the third or fourth week of my feedback and control class at UVM. Even
though electricity and magnetism shares many complimentary and parallel concepts,
for some reason thinking in terms of
magnetics when describing amplifiers, mixers, modulators, etc.,
has always caused brain freeze. Maybe it has to do with an ingrained bias due to
my earliest dealings with circuits being from a technician background before earning
an engineering degree. The equations of electric fields and magnetic fields are
very similar so that helps lower the barrier a bit. An engineer I worked with once
had the uncanny ability to comprehend time domain waveforms in the frequency domain,
and vice versa, when viewing an o-scope or spectrum analyzer display...
 Just about everyone who has worked in the
radar field for a long time is familiar with the name of
Dr. Robert M. Page. He was the first to come up with
the concept of monopulse radar, and he invented the familiar Plan Position Indicator
(PPI) radar display and the RF duplexer which allows one antenna to be connected
to both the transmitter and the receiver. Amazingly, I recently received an e-mail
from Dr. Page's son, John Page. An interest in his father's career
combined with insight that only growing up under the loving care of Dr. Page
can provide has afforded him some unique tidbits of information that many (most,
per John) historical accountings omit. Rather than me summarizing his letter...
 Biographical historians spend endless hours
searching old media for bits of information on their subjects. Finding useful material
on more renowned personalities is not a problem, but filtering out relevant bits
for a particular theme can be daunting. On the other hand, finding useful information
on lesser known people can be frustrating because there is so little information
readily available. Great Britain's World War II era superstar
Winston Churchill undoubtedly falls into the former category.
While scanning through my many vintage electronics and science magazines for interesting
fodder to post on RF Cafe, I'm always on the lookout for cameo appearances like
this one of Prime Minister Churchill talking on a walkie-talkie (aka "handie-talkie"
at the time) in this 1942 edition of Radio-Craft...
 New:
Rectangular Waveguide Calculator. RF Cafe's spreadsheet-based
engineering and science calculator,
Espresso
Engineering Workbook™, is a collection of electrical engineering and physics
calculators for commonly needed design and problem solving work. The filter calculators
do not provide just amplitude, but also phase and group delay (hard to get outside
of a big $$$ simulator). It is an excellent tool for engineers, technicians, hobbyists,
and students. Equally excellent is that Espresso Engineering Workbook™ is provided
at no cost, compliments of my generous sponsors. 51 worksheets to date...
 DAS DEALS Marketplace, RF Cafe's newest
supporter, is a B2B-only marketplace, meaning we exclusively work with established
businesses in the telecom, wireless, and networking industry to buy and sell
related products such as cables, antennas, DAS systems, RF passives, accessories,
and test equipment. All submissions are reviewed and approved before any products
are listed. Most products on DAS DEALS can be purchased directly using a credit
card at checkout. Can't find it on DAS DEALS? We probably know who has it. If you're
looking for a product that's not listed on our site, visit the
In-Demand Request page and submit a request.
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Loading history...
The RF Cafe Homepage
Archive is a comprehensive collection of every item appearing daily on this
website since 2008 - and many from earlier years. Many thousands of pages of unique
content have been added since then.
 When the electronics product world consisted
of vacuum tube based circuits, the physical sizes of standard fixed-value passive
resistors, inductors, and capacitors were not of much concern in terms of
how much volume they consumed. R's, L's, and C's, had wire leads protruding from
their molded bodies, or in the case of larger power supply filtering capacitors
had solderable tabs. Point-to-point wiring consisted of components and hookup
wire suspended in the air between solder terminal strips and tube base tabs.
Even with miniature (peanut) tubes, all but the largest passives had no
significant impact on overall unit size. Once semiconductors came onto the
scene, everything changed. Suddenly, even the standard 1/4 W carbon resistor and
tantalum capacitor became a significant factor when attempting to reduce size...
 This photo of
Ray Dolby holding one of his prototype noise reduction circuits is probably
the most widely published of him and therefore the most iconic of the Dolby noise
reduction system. Audiophiles of the era (and today for that matter) immediately
recognize the man who took the hisses and pops out of their beloved music. I always
like to keep in mind when reading article like this one in a 1971 issue of Radio-Electronics
magazine is that when it was originally published, Dolby had not yet become a household
word and news of his accomplishment was just getting out. Many articles, books,
and research papers have been written on how the Dolby system works. At least five
of them from the groundbreaking era have been posted here on RF Cafe, so you can
get some insight into the excitement. The technical term "companding"
(compressing and expanding) was being seen in print for the first time...
 Here is another electronics
challenge for you to try - the "Resistor
Function Quiz." It covers basic functions of resistors in various circuits. The
quiz appeared in the January 1962 edition of Popular Electronics
magazine, compliments of
Robert P. Balin. I got 100%, just for the record - PhD not required, by the
way. Having worked with tubes in the days of yore helps with figure B since it does
not really have a direct transistor equivalent, but by process of elimination you
can get it...
 Since 2000, I have been creating custom
technology-themed crossword puzzles for the brain-exercising
benefit and pleasure of RF Cafe visitors who are fellow cruciverbalists. The
jury is out on whether or not this type of mental challenge helps keep your gray
matter from atrophying in old age, but it certainly helps maintain your
vocabulary and cognitive skills at all ages. A database of thousands of words
has been built up over the years and contains only clues and terms associated
with engineering, science, physical, astronomy, mathematics, chemistry, etc. You
will never find a word taxing your knowledge of a numbnut soap opera star or the
name of some obscure village in the Andes mountains...
 The problem of and concern about our country's
youngsters seemingly not being overly interested in
pursuing technical career paths is a theme often heard in the tech news
media and workplaces. As our world grows increasingly automated and everything
from light bulbs to telephones and automobiles are so packed with "no user
serviceable parts inside," there seems to be little motivation for an otherwise
potential budding tinkerer to take stuff apart to discover what makes it work.
In the "old days" like, say, 1955, products were much more accessible to kids'
curious nature and explains why fostering the next crop of engineers,
scientists, and technicians took care of itself. You might think so, but alas,
the dilemma evidently persists with each succeeding generation...
 Here is a fairly simple
quiz on AC circuit analysis. If you are not already comfortable with adding
series and parallel circuits containing resistors, capacitors, and inductors, you
will appreciate the simple formula presented that will keep the sweat level down
;-) . An even simpler form that solves explicitly for the four variables are
as follows: VTotal = √ [(VL - VC)2
+ VR2]
VR = √ [(VT)2 - (VL - VC)2]
VL = VC + √ [VT2 - VR2]
VC = VL - √ [VT2 - VR2]
OK, pick up your pencils... now...
 Back in 2012, I posted a video of the PBS
"Frontline" show (Cell Tower Deaths) that highlighted the dangers cell tower climber
technicians face while working for very low wages. Other news stories since then
have reported on new regulations from OSHA and other agencies that have helped make
the safety issue better, but I haven't seen anything on whether the pay has gotten
any better. There are lots of videos and photos online of
tower climbers
all over the world, but this one showing tower climber Kevin Schmidt making the
ascension to the very top of the now inactive KDLT TV analog broadcast antenna
near Salem, SD, is unique in that the recording was made from a drone platform.
It has more than 12 million views. Capturing this kind of video requires a drone
with a wireless live feed so the pilot...
 An alternate title for this article that
appeared in a 1969 issue of Radio-Electronics magazine could have been,
"How
to Build a J-K Flip-Flop." Author Leonard Geisler takes the reader through a
step-by-step assembly of a functional J-K flip-flop using a collection of 1- 2-
and 3-input NAND gates. The 1-input NAND, in case you are wondering, is used as
an inverter. The piece reads like an in-depth first-semester electrical engineering
technician course textbook. In the process of building the J-K, an R-S (reset/set)
flip-flop is described. Nowhere does Geisler offer an explanation of from where
the "J" and the "K" input labels come. According to electrical engineer Sourav
Bhattacharya blog, it was Dr. Eldred Nelson of Hughes Aircraft who first coined
the term J-K flip-flop...
 This you need to see. The full story behind
this video is unknown, but supposedly customers were complaining about poor reception
associated with the Bear Creek Road microwave station somewhere in northern California.
Upon inspection, the technicians discovered a small hole in the radome. When the
cover was pulled away, according to the video somewhere between 35 to 50 gallons
of
acorns
spilled out. You can see the bulge in the radome before emptying. The tech
probably thought the water drain hole was clogged and it was full of water. From
a National Geographic story: "Walter Koenig, a senior scientist with the Cornell
Laboratory of Ornithology, says he's pretty sure the the acorn woodpecker..."
 The term "ovonic" - a fairly unfamiliar word
these days - appeared in the May edition of Radio-Electronics, in an article
entitled, "All About Ovonics," just a few months after this news item ran in the
January issue (which I posted last month). Ovonics is a portmanteau of "Ovshinsky"
(from Stanford R. Ovshinsky, the inventor) and "electronics." Read the "All About
Ovonics" article for a deeper dive into the subject. The big deal, which turned
out to be not a big enough deal, was the use of
amorphous "glassy" compounds as semiconductors rather than the standard
crystalline silicon structures. Maybe someday an enterprising genius inventor
type will give a rebirth to the concept...
 One of the monthly columns in R/C Modeler
magazine, written by Chuck Cunningham, entitled "Cunningham on R/C," that reported
on the current state of radio control, which had only fairly recently evolved into
fully solid state, proportional control systems. Anyone involved in electronics
is painfully familiar with the weird kinds of issues that crop up in complex circuits
that operate in hostile environments. The March 1970 issue contained part of an
article authored by D. L. Klipstein, Director of Engineering, Measurement Control
Devices, entitled, "Murphy's Law: The Contributions of Edsel Murphy to
the Understanding of the Behaviour of Inanimate Objects.*" Only a few of the
items were printed in Cunningham's column, but I managed to locate a copy of the
full article...
 This is a story with a lesson learned by
the author and thousands of others ever since electric power appliances and tools
first became available. Fortunately, his Ham buddy was not permanently harmed, but
even today with all the effort put into educating the public, people continue to
use ungrounded (2-wire type, or with the ground prong removed) extension cords in
conjunction with 3-wire power cords on tools and end up
electrocuting
themselves (or somebody else). I've told the story before about a friend of mine
from high school who shortly after graduation was making a piece of furniture in
a garage that had a damp dirt floor, and was electrocuted to death by the
metal-framed circular saw that had no ground connected. Nowadays we often have
power provided by a GFCI receptacle...
 "Rediscovery
of FM Broadcasting" could be a contemporary headline. The decline of
broadcast radio has been a major concern of station owners for well over a
decade since Internet and satellite radio has dominated the venue through which
listeners access radio stations. Local broadcasters have long aired syndicated
programs that include national advertising, but the money to pay for those
segments came from revenue supplied largely by local companies. FM broadcasting
began commercially around 1945 in the familiar 88-108 MHz band yielded by the
military following World War II, and grew in number of stations very rapidly in
the first few years. Then, it began a decline for a few more years until finally
leveling off after about a decade. Even though FM had a clear advantage
(literally) over AM because of electrical noise immunity...
 My daughter, Sally, in addition to owning
and operating a very successful horse riding school named Equine Kingdom Riding
Academy, has a rather large eBay store she uses as a venue for selling items purchased
at the local Goodwill "Bins" store. She often buys vintage toys with electronics
features - sometimes working and sometimes not. A properly functioning vintage toy,
be it a stuffed animal or a game of some sort, can make a huge difference in the
resale price. When that is the case, she sends them home with me to attempt a repair.
Many times the problem is corroded contacts from leaky batteries. A dental pick
and some isopropyl alcohol usually solves the problem. When that doesn't work, it's
time to open 'er up for a deeper look. Over the years I have found problems
ranging...
 All college curricula seem to have a number
of particular "weeding out" courses that cull the herd - so to speak - from the
eventual graduating class. The unfortunate victims are then faced with either dropping
out of college (not always such a dooming fate) or choosing a different major. For
mechanical engineers (MEs) it was often statics; for electrical engineers (EEs)
it was
AC circuits - the topic of this article. DC is relatively simple because
voltage and current is always in phase, thus no "hard" vector math is involved,
but throw in reactance with its attendant non-zero phase angles and suddenly the
student is faced with trigonometry - the kiss of death to mathphobes. My experience
in engineering school showed that for MEs who lived through statics, dynamics provided
the next level of weeding out (it nearly got me). For EEs it was Fourier and Laplace
transforms. Level three for MEs was thermodynamics (thermogodda**ics was a
popular alternate title)... |
