|
 The
bridged-T filter is a quick-and-dirty construct used to notch out a specific
frequency that is interfering with a desirable frequency or band of frequencies.
It is a resonant LC (inductor-capacitor) circuit consisting of a single inductor
"bridging" a pair of series capacitors having a resistor to ground between them,
or, if preferred, a capacitor bridging one or two inductors. A convenient
nomogram (aka nomograph) is provided by the author in this 1964
Radio-Electronics magazine article for quickly selecting values, which was
a very popular design aid in the pre-calculator era. A slide rule could be used
to calculate a range of values when only a single variable was in play, but
juggling more than one variable (component value) was greatly aided by a
multivariable nomograph. Truth is nomographs can still...
 Television, in 1955, was still a relatively
new phenomenon to many - maybe even most - people. According to multiple sources,
the portion of American households with a TV set went from under 20% in 1950 to
nearly 90% ten years later in 1960. That was a meteoric rise, particularly considering
the expense of even a minimal TV. The technology was not even available commercially
when most people were born, so the rush to join in on the craze was akin to the
mass adoption of cellphones in the 1990s. "Carl &
Jerry" creator John Frye used his pair of electronics-savvy teenagers to help
make the "magic" behind recreating a moving picture on a CRT miles away from where
it was created. Water flowing through a garden hose has often been employed as an
analogy for current flowing through a wire to explain electricity to laymen and
beginning students of the craft. Here, it is not water flowing through the hose
but water leaving the hose and flowing through the air that serves to represent
an electron stream travelling from the electron gun to the phosphor-coated glass
front of a CRT. Frame rates, scan lines, deflection coils, and other relevant terms
are i
 "The
RF front-end (RFFE) industry, valued at $21 billion, is expanding beyond its
traditional focus on mobile and infrastructure to drive innovation in the automotive
sector. Each segment within the industry presents unique dynamics and growth opportunities.
After a difficult 2022, the smartphone market is showing signs of recovery, with
expected year-over-year growth of 4%, projected to reach 1.2 billion units by 2024.
The mobile RFFE market is predicted to hit US$18 billion by the end of 2024, though
it may face stagnation due to market saturation and pricing pressures. This
market is expected to expand, with the 2027 launch of RedCap..."
 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...
 Temwell is a manufacturer of
5G wireless communications filters for aerospace, satellite communication, AIoT,
5G networking, IoV, drone, mining transmission, IoT, medical, military, laboratory,
transportation, energy, broadcasting (CATV), and etc. An RF helical bandpass specialist
since 1994, we have posted >5,000 completed spec sheets online for all kinds
of RF filters including helical, cavity, LC, and SMD. Standard highpass, lowpass,
bandpass, and bandstop, as well as duplexer/diplexer, multiplexer. Also RF combiners,
splitters, power dividers, attenuators, circulators, couplers, PA, LNA, and obsolete
coil & inductor solutions.
 Here we are with another set of three "What's
Your EQ?" circuit challenges, these from the February 1962 issue of Radio-Electronics
magazine. As usual, those challenges provided by Jack Darr are the purview of television
servicemen of the era. The photo shown of the problematic CRT display looks like
a chest x-ray or maybe hieroglyphics in the dark corner of a cave, but evidently
the artifacts are readily identifiable to an initiated few. The Forbidden Current
Path circuit answer is not what I thought it would be. I maintain that whether my
answer or the designer's answer is correct depends on the physical...
 "A new
world record
in wireless transmission, promising faster and more reliable wireless communications,
has been set by researchers from UCL. The team successfully sent data over the air
at a speed of 938 Gb/s over a record frequency range of 5–150 GHz. This speed
is up to 9,380 times faster than the best average 5G download speed in the UK, which
is currently 100 Mb/s or over. The total bandwidth of 145 GHz is more
than five times higher than the previous wireless transmission world record. Typically,
wireless networks transmit information using radio waves over a narrow range of
frequencies..."
 Sputnik refers to the first series of satellites
launched by the Soviet Union. The word "Sputnik" means "satellite" in Russian. The
launch of Sputnik 1 on October 4, 1957, marked a monumental moment in human history,
heralding the dawn of the Space Age and sparking a fierce technological competition
known as the Space Race between the United States and the Soviet Union. This satellite,
the world's first artificial one, orbited Earth at an altitude of roughly 215 to
939 kilometers and broadcast a radio signal that astonished the world, particularly
in the United States, where it spurred rapid advancements in aerospace and scientific
research. The successful launch of Sputnik was an achievement that was years in
the making, involving a combination of visionary planning, political motives, and
intensive engineering by some of the Soviet Union's top scientists.
Blog: Air Quality
Measurements with Particle Counters
 Transcat | Axiom Test Equipment, an electronic
test equipment rental and sales company has published a new blog post entitled "Provide
Essential Air Quality Measurements with These Particle Counters" that covers
how particle counters can provide essential measurement capabilities that can help
avoid contamination and support high manufacturing yields. These measurement tools
can detect and measure microscopic particles suspended in air that can contaminate
the most carefully planned manufacturing lines. Air particle counters can be designed
for various...
 In 1958, most people were not accustomed
to seeing the now-familiar maps plotting
sinusoidal
courses of satellites across the face of the earth. It had only been in October
of the previous year that any object other than the moon was in orbit around our
home planet - that was U.S.S.R.'s Sputnik. Just as people of all ages and all backgrounds
enthusiastically joined in the newfangled phenomenon of aeroplanes after the Wright
Brothers flew their fragile craft at Kitty Hawk, electronics communications and
scientists worldwide hopped aboard the satellite train. This article from a 1958
issue of Radio & TV News magazine provided insight into the construction
and flight characteristics...
 LadyBug Technologies was founded in 2004
by two microwave engineers with a passion for quality microwave test instrumentation.
Our employees offer many years experience in the design and manufacture of the worlds
best vector network analyzers, spectrum analyzers, power meters and associated components.
The management team has additional experience in optical power testing, military
radar and a variety of programming environments including LabVIEW, VEE and other
languages often used in programmatic systems. Extensive experience in a broad spectrum
of demanding measurement applications. You can be assured that our Power Sensors
are designed, built, tested and calibrated without compromise.
 What were some of the
top issues of the radio and television industry half a century ago? In a lot
of respects, the same things that concern it today. A ready supply of service technicians
was a concern that was taken seriously by the Electronics Industry Association (EIA).
While there are not many local repair shops for electronics products nowadays, there
is still a huge demand to techs who are willing and able to do the hard work of
keeping the world's communication infrastructure operational - climbing towers,
repairing cell equipment. Now, as then, good pay, job security, benefits, and respect
for the job being done were at the top of...
 In a parallel to the traditional test setup
of signal generation and signal acquisition, RIGOL Technologies announced today
the latest additions to its portfolio of
performance measurement equipment with the introduction of the DG5000 Pro Series
Generators and DHO/MHO5000 Series Oscilloscopes. The DHO/MHO5000 Series bring next-level
performance to RIGOL's respected line of high-resolution oscilloscopes, while the
DG5000 Pro generators do the same for the company's capable Pro Series arbitrary
waveform generators...
 When selecting articles for posting here
on RF Cafe, I like to include ones that are directed toward newcomers to the field
of electronics as well as for seasoned veterans. This piece from a 1958 issue of
Radio & TV News magazine entitled "Basic Electronic Counting," is a
prime example in that it introduces the concept of binary numbers. We've all been
there at some point in our careers. A big difference between now and when this article
appeared is that in 1958, almost nobody was familiar to binary numbers, and fuggetabout
[sic] octal and hexadecimal. Only those relatively few people designing and working
with multimillion dollar, vacuum tube-based digital computers installed in universities,
megacorporations, and government research facilities had ever dealt with digital
numbers. The earliest example of powers of two I remember was back in junior high
school. It had to do with a
 "Every invention begins with a problem -
and the creative act of seeing a problem where others might just see unchangeable
reality. For one 5-year-old, the problem was simple: She liked to have her tummy
rubbed as she fell asleep. But her mom, exhausted from working two jobs, often fell
asleep herself while putting her daughter to bed. 'So [the girl] invented a teddy
bear that would rub her belly for her,' explains Stephanie Couch, executive director
of the Lemelson MIT Program. Its mission is to nurture the
next generation of inventors
and entrepreneurs. Anyone can learn to be an inventor, Couch says, given the right
resources and encouragement. 'Invention doesn't come from some innate genius, it's
not something that only really..."
 Mechanical filters of the type described
in this 1969 Electronics World magazine article are yet another example
of the genius of some people. They are actually a form of electromechanical device
in that the applied electrical signals are first converted into mechanical signals,
followed by resonant mechanical elements that discriminate according to frequency,
and finally a conversion back to an electrical signal is made. It is fundamentally
the same principal as a crystal, SAW, or BAW filter, albeit each with distinctly
different methods and topologies. Mr. Donovan Southworth, of Collins Radio, presents
the basics of mechanical filters in this brief write-up...
LadyBug Technologies was founded in 2004
by two microwave engineers with a passion for quality microwave test instrumentation.
Our employees offer many years experience in the design and manufacture of the worlds
best vector network analyzers, spectrum analyzers, power meters and associated components.
The management team has additional experience in optical power testing, military
radar and a variety of programming environments including LabVIEW, VEE and other
languages often used in programmatic systems. Extensive experience in a broad spectrum
of demanding measurement applications. You can be assured that our Power Sensors
are designed, built, tested and calibrated without compromise.
 Attempts at making an
electronically printed facsimile (fax) of an original document at a location
distant from the source have been around for quite a while. As mentioned by
Radio-Electronics magazine editor Hugo Gernsback in this article, Samuel Morse
had a crude working device for printing messages on paper even before his eponymously
named code of dots and dashes became famous in 1837. A couple decades earlier, a
fellow named John Redman Coxe, of Philadelphia, Pennsylvania, devised a method of
electronically printing images and text on paper using a conductive solution and
a direct current pile (aka battery). Dr. Coxe, a physician, is not a well-known
figure in the electronics world, but in his day...
 "Researchers have discovered how the 'edge
of chaos' can help electronic chips overcome signal losses, making chips simpler
and more efficient. By using a metallic wire on a semi-stable material, this method
allows for long metal lines to act like superconductors and amplify signals, potentially
transforming chip design by eliminating the need for transistor amplifiers and reducing
power usage. A stubbed toe immediately sends pain signals to the brain through several
meters of axons, which are composed of highly resistive fleshy material. These axons
operate using a principle known as the 'edge of chaos,' or semi-stability, enabling
the swift and precise transmission of information..."
 The January 1969 issue of Electronics
World magazine published an extensive list of
Japanese company trade names and their addresses. Many of them went out of business
or were bought by other corporations long ago, as occurs in all countries. "Aiwa"
is listed twice, but that might have been a legitimate duplication due to separate
locations (BTW, I owned an Aiwa stereo at one time). My first "real" cassette tape
deck was made by TEAC (founded in 1953 as the Tokyo Electro Acoustic Company) and
my first "real" stereo receiver was made by Sansui. I remember the line in "Back
to the Future 3" where Doc Brown, having time-travelled from 1955, makes a
disparaging remark about a circuit in the DeLorean failing because of it being labeled
"Made in Japan." Marty counters...
• ARRL Defends
902-928 MHz Amateur Radio Band
• FCC's
Auto Safety Spectrum Rules
• $5M in U.S.
Chips Act Money to Metrology Projects
• U.S. State Department Approves
Surveillance Radar System Sale to Romania
•
5G Americas ITU IMT-2030 Vision for 6G White Paper
 John Redman Coxe was a prominent American
physician, scientist, and innovator born on September 20, 1773, in Philadelphia.
Coxe's intellect and curiosity drove him toward an illustrious career in both medicine
and early scientific exploration, which included experimentation in electrochemistry.
He graduated with a degree in medicine in 1794, setting the course for his lifelong
journey into medicine and early scientific innovation. Coxe broadened his approach
to medicine and science, inspiring him to explore the convergence of scientific
methods and practical applications. John Redman Coxe is most remembered not only
for his contributions to medicine but also for his interest in experimental physics,
particularly in the field of electrochemistry...
 TotalTemp Technologies has more than 40
years of combined experience providing thermal platforms.
Thermal Platforms are
available to provide temperatures between -100°C and +200°C for cryogenic cooling,
recirculating & circulating coolers, temperature chambers and temperature controllers,
thermal range safety controllers, space simulation chambers, hybrid benchtop chambers,
custom systems and platforms. Manual and automated configurations for laboratory
and production environments. Please contact TotalTemp Technologies today to learn
how they can help your project.
 When I saw this 1966 Radio-Electronics
magazine article entitled, "Vibration
and Shock - Nature's Wrecking Crew," for some reason the first thing I thought
of was "The Wrecking Crew," that anonymously played the music for a huge number
of popular singers - mostly those without prominent bands of their own during the
1960s and 1970s rock-and-roll era. ...but I digress. My introduction to the potential
deleterious effects of vibration on electronics was in the 1970s, with airborne
receivers and servos in my radio controlled model airplanes. Even though they were
transistorized, vibration from glow fuel engines could wreak havoc with potentiometers
in servos and solder joints everywhere, including battery packs. I remember seeing
the control surfaces jitter...
 You don't see jobs advertisements like this
anymore. Here is an ad that appeared in the the July 1944 edition of QST
(the American Radio Relay League's, ARRL's, monthly magazine), placed by Raytheon
Manufacturing Company (now just Raytheon Company), looking for
vacuum tube design, test, and processing engineers. Licensed amateur radio operators
were in high demand during the war years because of their knowledge and enthusiasm
for electronics and wireless communications. I hope you didn't come to this page
hoping to really find a tube designer job available. Of course, there are still
vacuum tubes being designed for TWTs and magnetrons, but those are few and far between...
 The "carborundum"
signal detector, an innovative device developed by engineer General H. H. C. Dunwoody
in the early 20th century, represents a significant advancement in radio technology,
particularly in the context of crystal detectors used for receiving radio signals.
This device utilized the unique properties of silicon carbide, also known as carborundum,
which was synthesized in the late 19th century by Edward Goodrich Acheson. The connection
between Dunwoody and the material lies in the application of carborundum as a semiconductor
in radio signal detection. The operational theory of the carborundum signal detector
is rooted in its ability to rectify alternating current (AC) signals. When radio
waves, which are essentially electromagnetic waves...
 "Researchers have created a cutting-edge
structure by placing a very thin layer of a special insulating material between
two magnetic layers. This new combination acts as a quantum anomalous Hall insulator,
significantly broadening its potential use in developing ultra-efficient electronics
and innovative solar technology. A Monash University-led research team has found
that a structure featuring an ultra-thin topological insulator, sandwiched between
two 2D ferromagnetic insulators, transforms into a large-bandgap quantum anomalous
Hall insulator. This heterostructure opens the door to ultra-low energy electronics
and even topological photovoltaics..."
|
 In 1945 when this series was published in
Radio-Craft magazine,
microwaves were pretty much the realm of corporate and university
research laboratories and - often coincidentally - secret Department of War projects.
Radar was the primary application, although some work was being done on high bandwidth
communications by the aforementioned entities, in some cases following in the footsteps
of amateur radio operator's discoveries about how the higher frequencies were affected
by the ionized layers of the Earth's atmosphere. Immediately following the end of
World War II, the government began declassifying a lot of information learned
about microwave, and magazines were fast to pick up on it. In fact, there were instances
where editors saw fit to write columns asserting their right to do so when criticisms
were heaped upon them by readers accusing them of divulging critical security-related...
 "Modern" used in the title of anything has
always bothered me since it is utterly ambiguous unless you know the era of the
authorship. There are plenty of books using "Modern Medicine" in the title that
describe bloodletting as a treatment for various diseases or swallowing mercury
to cure constipation (and just about everything else). Accordingly, apologies to
anyone searching for 2021-modern television information who might have wandered
in here hoping to find useful information. However, if you are looking for historical
data regarding the evolution of broadcast television, then you might be in the right
place. As usual when reading this kind of article from a 1939 issue of Radio
News magazine, I am amazed to see accounts of the very first thoughts on the
path technology takes toward where we find ourselves in 2021.
There are basically two types of "visionaries" - those who first come up with
a new idea and those who actually implement the vision. Often the same person qualifies
for both categories. Being the first person to think up the idea of sending voice
signals or images through the air to a remote location...
 Oddly, the article does not tell you the
origin of the acronym "WAVES." From the U.S. Navy's history page: "After a twenty-three-year
absence, women returned to general Navy service in early August 1942, when Mildred
McAfee was sworn in as a Naval Reserve Lieutenant Commander, the first female commissioned
officer in U.S. Navy history, and the first Director of the WAVES, or "Women Accepted
for Volunteer Emergency Service". In the decades since the last of the Yeomen (F)
left active duty, only a relatively small corps of Navy Nurses represented their
gender in the Naval service, and they had never had formal officer status. Now,
the Navy was preparing to accept not just a large number of enlisted women, as it
had done during World War I, but female Commissioned Officers to supervise them.
It was a development of lasting significance, notwithstanding the WAVES' name, which
indicated...
 Back in the 1960s, Robert Balin created many
quizzes on various electronics topics for Popular Electronics magazine.
I have posted many of them (see complete list below). This one from the May 1962
issue is on the subject of
units of measure commonly found in electronics work. All are still found in
modern devices, so you don't need to be an expert on vacuum tubes and selenium rectifiers
to get a good score. I missed the one for the tape deck, but then I don't ever remember
concerning myself with the electrical and magnetic characteristics of tape decks.
Maybe you will do better.
 The discussion of waveguides, up to this
point, has been concerned only with the transfer of energy from one point to another.
Many waveguide devices have been developed, however, that modify the energy in some
fashion during transit. Some devices do nothing more than change the direction of
the energy. Others have been designed to change the basic characteristics or power
level of the electromagnetic energy. This section will explain the basic operating
principles of some of the more common waveguide devices, such as
Directional Couplers, Cavity Resonators, and Hybrid Junctions. The directional
coupler is a device that provides a method of sampling energy from within a waveguide
for measurement or use in another circuit. Most couplers sample energy traveling
in one direction only. However, directional couplers can be constructed that sample
energy in both directions...
 This assortment of custom-designed themes
by RF Cafe includes T-Shirts, Mouse Pads, Clocks, Tote Bags, Coffee Mugs and Steins,
Purses, Sweatshirts, Baseball Caps, and more, all sporting my amazingly clever "RF Engineers - We Are the World's Matchmakers"
Smith chart design. These would make excellent gifts for husbands, wives, kids,
significant others, and for handing out at company events or as rewards for excellent
service. My graphic has been ripped off by other people and used on their products,
so please be sure to purchase only official RF Cafe gear. I only make a couple bucks
on each sale - the rest goes to Cafe Press. It's a great way to help support RF
Cafe. Thanks...
 Banner Ads are rotated in all locations
on the page! RF Cafe typically receives 8,000-15,000 visits each
weekday. RF Cafe
is a favorite of engineers, technicians, hobbyists, and students all over the world.
With more than 17,000 pages in the Google search index, RF Cafe returns in
favorable positions on many types of key searches, both for text and images.
Your Banner Ads are displayed on average 225,000 times per year! New content
is added on a daily basis, which keeps the major search engines interested enough
to spider it multiple times each day. Items added on the homepage often can be found
in a Google search within a few hours of being posted. If you need your company
news to be seen, RF Cafe is the place to be...
 Since we seem to be on a roll of FM radio
theme articles printed in vintage electronics magazine, here is one from a 1973
issue of Popular Electronics. The author never explicitly tells us the date when
the Institute of High Fidelity (IHF) updated its
FM tuner specifications, and neither does he mention groundbreaking work of
IHF's Julian Hirsch, who is largely responsible for both the initial and updated
standards. If you read magazine stereo equipment reviews in the 1960s and 1970s,
then you probably recall the name. Anyway, this article discusses the improved specifications
made possible by more sophisticated circuits made possible by semiconductors and
miniaturized passive components. Interestingly, by 1973 magazines had gone from
abbreviating decibels from d.b. to dB, from k.c. and m.c. to kHz and MHz, from m.m.v.
to (μV), and from r.f. to RF, but they still used i.f. (intermediate frequency)
rather...
 This Radio Service Data Sheet provides schematics
and parts lists for
Westinghouse Models H-161, H-168 and H-168A receivers. Most -
if not all - electronics servicemen had subscriptions to these magazines because
they were a ready source of not just these service sheets, but because of the extensive
articles offering advice on servicing radios and televisions. In fact, many electronics
manufacturers had a policy of supplying service data only to bona fide shops. A
large list is included at the bottom of the page of similar documents from vintage
receiver schematics, troubleshooting tips, and alignment procedures. They were originally
published in magazines like Radio-Craft, Radio and Television News,
Radio News, etc. I scan and post them for the benefit of hobbyists who
restore and service vintage...
 Here is an unusual twist in waveform recognition
presented by Radio-Electronics' and Popular Electronics' quizmaster,
Robert Balin. If you happen to be a former analog television repairman, then you
will probably recognize the answers based on your many years of diagnosing faulty
horizontal or vertical
sweep circuits. If not, then you might need to strain the "little gray cells"
a bit, as Agatha Christie's premier sleuth Hercule Poirot might say. The instructions
say to assume that if you choose the horizontal sweep sawtooth to be the errant
signal, then assume the vertical sweep sawtooth is correct, and vice versa. Right
off the bat, waveform 8 is unique enough to easily identify the sweep that would
produce it since only one has two repeating components. Most of the others can be
readily deduced, too, by mentally following the x and y points as the "correct"
sweep...
This assortment of custom-designed themes
by RF Cafe includes T-Shirts, Mouse Pads, Clocks, Tote Bags, Coffee Mugs and Steins,
Purses, Sweatshirts, Baseball Caps, and more, all sporting my amazingly clever "RF Engineers - We Are the World's Matchmakers"
Smith chart design. These would make excellent gifts for husbands, wives, kids,
significant others, and for handing out at company events or as rewards for excellent
service. My graphic has been ripped off by other people and used on their products,
so please be sure to purchase only official RF Cafe gear. I only make a couple bucks
on each sale - the rest goes to Cafe Press. It's a great way to help support RF
Cafe. Thanks...
Banner Ads are rotated in all locations
on the page! RF Cafe typically receives 8,000-15,000 visits each
weekday. RF Cafe
is a favorite of engineers, technicians, hobbyists, and students all over the world.
With more than 17,000 pages in the Google search index, RF Cafe returns in
favorable positions on many types of key searches, both for text and images.
Your Banner Ads are displayed on average 225,000 times per year! New content
is added on a daily basis, which keeps the major search engines interested enough
to spider it multiple times each day. Items added on the homepage often can be found
in a Google search within a few hours of being posted. If you need your company
news to be seen, RF Cafe is the place to be...
 Chapter 8 of the U.S. Navy's basic electronics
course of study, titled "The Series Circuit: Why Know Circuits?" introduces the concept
of series electrical circuit analysis. After discussing basic characteristics and
applications of resistors, capacitors, inductors, conductors, and insulators, analyzing
series circuits are traditionally the beginning point for fledgling technicians,
scientists, hobbyists, and engineers. Purely resistive series circuits have just
one current path with the same value through every component, making calculations
extremely simple. Things start getting a bit tougher when reactive components are
introduced, but simple trigonometry takes care of that. The move into parallel circuits
is typically the first barrier that washes out students least likely to succeed.
A few guys in my USAF tech school had to change career fields after about the third
weeks of Basic Electronics because they could not grasp...
 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...
 Each week, for the sake of all avid cruciverbalists
amongst us, I create a new
technology-themed crossword puzzle using only words from my custom-created lexicon
related to engineering, science, mathematics, chemistry, physics, astronomy, etc. You
will never find among the words names of politicians, mountain ranges, exotic foods or
plants, movie stars, or anything of the sort. You might, however, see someone or something
in the exclusion list who or that is directly related to this puzzle's theme, such as
Hedy Lamar or the Bikini Atoll, respectively...
 The January 1947 issue of Radio-Craft
magazine was dedicated to editor Hugo Gernsback to articles celebrating the 40th
anniversary of his personal friend Lee de Forest's invention of the Audion
amplifying vacuum tube. Click on the Table of Contents link to access many of the
other articles - all of which are very insightful into the many amazing activities
of Mr. de Forest. Many of the articles were written by friends and business
associates of him. The "radiophone"
addresses here is actually one of the earliest mobile phone, being interconnected
by radio signals rather than a twisted pair of wires. Take note of the "flame audion"
mention, which believe it or not describes de Forest's earliest experiments
which used a pair of salted platinum plates embedded in an actual flame. Yes, that
actually constituted an amplifying element...
 "Short waves," with their ability to support
long distance communications under certain conditions, became a phenomenon in the
late 1920s, and a market developed for converting commercial broadcast receivers
to
short wave receivers. Magazines at the time were full of advertisements
for the devices. The particulars of short waves and the way they propagated in the
upper atmosphere were not yet well understood early on. In fact, the government
considered transmission frequencies above 1.5 MHz (≤200 meters) so useless
that they assigned those bands to amateur radio operators. The presence of an electrically
conductive layer, known as the ionosphere, was not verified until 1927 by Edward
Appleton...
 As one who has been dealing with using and
recharging batteries - both individual cells and wired packs - for about five decades,
I have used many varieties of chargers and battery chemistries. As you probably know,
there are two basic types of cells: primary and secondary. Based on their construction
and chemistry, the former are not designed to be recharged while the latter are. Primary
cells include zinc-carbon and standard alkaline. Secondary cells include nickel-cadmium
(NiCd), nickel-metal-hydride (NiMH), and lithium polymer (Li-Po). Rechargeable batteries
can have their discharge cycle reversed by running an externally supplied current through
the cell in the opposite direction. Of course there are optimal conditions by which that
current must be fed...
 An article
titled "One Receiver - All Bands" that appeared in the January 1963 issue
of Popular Electronics was a single tube receiver design, but the trick
to using a single tube was that the it was actually three tubes in one - a 6AF11
compactron.
It contained two separate triodes and a pentode within the same glass capsule. A
modern equivalent would be to use an integrated circuit (IC) package that contains
three or more opamps in the same package. In fact, variations on compactrons that
included internal biasing components were referred to as integrated circuits. This
article from the October 1960 edition of Electronics World reported on
the engineering behind compactron vacuum tubes ...
 If you like the
radio-themed comics from vintage electronics magazines, then you'll appreciate
the jackpot of them (5) in the July 1945 issue of Radio Craft magazine.
Being the era in which it was published, many of the comics at the time had military-electronics
themes as well. A lot of them are credited to subscribers providing ideas. One of
my favorite features is "Radio Terms Illustrated," where readers write in with suggestions
for how common lingo in the radio realm can have an alternate interpretation. Such
is the case with "Wave Trap" in the first comic. I think Frank Beaven was the illustrator
for all of them. Look in the big list of other technical-themed comics at the bottom
of the page for others which include "Radio Terms Illustrated."
 A new reference page on
superconductivity
has been added to RF Cafe. Values for many superconductive materials are pulled from
my copy of Reference Data for Radio Engineers, Sams Publishing. Use of superconducting
materials in electrical machinery and transmission lines would mean significant savings
in power generation requirements because all supplied power would be converted to useful
work. At this point in time there have been test cases of nitrogen-cooled superconducting
cables for commercial AC power transmission, but the cost benefit is negative. As of
2015, the highest temperature superconductor compound was mercury barium calcium copper
oxide (HgBa2Ca2Cu3O8) at around 133...
 This is part of a series published by
Radio News and the Short-Wave magazine in the early 1930s. As with most topics
pertaining to electronics, the theory is still relevant and applicable to many modern
circuits and systems.
Piezoelectric principles are introduced for determining the frequency
of oscillators. I have to admit to not having heard of the 'pyroelectric' effect.
A pyroelectric crystal when heated or cooled develops charges on the extremities
of its hemihedral (another new word for me, meaning "exhibiting only half the faces
required for complete symmetry") axes. Types other than the familiar quartz include
tourmaline, boracite, topaz, Rochelle salts, and even sugar. Read on to learn more ... |
