In his June 1963
Radio-Electronics magazine article, Edward Finkel introduces the
Log Periodic V (LPV) antenna, a breakthrough in VHF TV reception, overcoming
the narrow-band limitations of traditional Yagi designs by employing log-periodic
scaling (τ = 0.9, σ = 0.085) to achieve uniform gain (8 dB low-band, 11.5 dB
high-band), constant impedance (~1.2 VSWR), and a 35 dB front-to-back ratio
across 54-216 MHz. Developed by University of Illinois researchers and JFD
Electronics, the LPV uses "active cells" where resonance shifts smoothly with frequency,
leverages third-harmonic resonance for high-band channels (7-13), and enhances directionality
via forward-V elements and a phase-reversed feeder harness to cancel rear/side signals
(Figs. 5-7). Reinforced...
"RIKEN scientists have discovered how to
manipulate molybdenum disulfide into acting as a superconductor, metal, semiconductor,
or insulator using a
specialized transistor technique.. By inserting potassium ions and adjusting
conditions, they could trigger dramatic changes in the material’s electronic state
- unexpectedly even turning it into a superconductor or insulator. This new level
of control over a single 2D material could unlock exciting breakthroughs in next-gen
electronics and superconductivity research. A team of physicists at RIKEN has developed
a transistor-based technique that allows a single-layered material to take on a
wide range of electronic behaviors, functioning as a superconductor, metal, semiconductor,
or insulator..."
Hugo Gernsback, publisher of Radio-Electronics
magazine, penned this 1962 article critiquing the U.S. for
lagging behind the Soviets in manned spaceflight, noting their superior orbital
achievements (130.5 orbits vs. America's 12). He argues that prolonged Earth-orbiting
tests are unnecessary, as weightlessness and space sickness - predicted decades
earlier - are now proven manageable. Gernsback traces U.S. delays to the government's
historical neglect of rocketry pioneer Robert H. Goddard, whose early 20th-century
work could have secured American leadership. Instead of mimicking Soviet Earth orbits,
he urges immediate focus on the Moon, prioritizing an unmanned electronic...
Copper Mountain Technologies' Brian Walker,
has published a new white paper entitled "Hardware
Triggering a Vector Network Analyzer." In it, he details the use of hardware
triggering in VNAs to synchronize measurements with external test equipment, such
as programmable power supplies or pulsed RF signals. It explains how external triggering
- either "On Sweep" or "On Point" - enables precise control over VNA operations,
reducing power dissipation in devices like RF power amplifiers. The paper
outlines SCPI commands for automation, including triggering, polling data, and checking
VNA status, with examples in Python-like syntax. It also covers trigger voltage
levels, polarity settings, and timing modes, including programmable delays for pulsed
RF measurements. The document highlights Copper Mountain Technologies' VNAs, which
support these features...
In this 1967 Radio-Electronics
magazine article, Sally O. Smyth highlights
pioneering women in electronics, challenging the male-dominated industry stereotype.
Muriel Burke and Kathi Kramer, sisters running a successful TV repair shop for a
decade, emphasize problem-solving and customer trust. Cecilia Jacobs, a financial
consultant turned electronics firm owner, showcases innovation in military and security
tech. Vicki Labes, trained by her husband, co-manages an audio-visual business and
produces films. Self-taught technician Mrs. William Nolan transitioned from fixing
a tape recorder to technical writing. Francis Brooks, an RCA Institutes graduate,
designs circuit boards while...
Charles J. Vlahos' 1968 Radio-Electronics
magazine article highlights the growing popularity of
shortwave listening (SWL), still a popular pastime, with around 3,000 stations
worldwide broadcasting diverse content - news, propaganda, language courses, and
entertainment - often in English. SWL offers unique perspectives, from Hanoi's war
coverage to Radio Tokyo's language lessons. Enthusiasts log stations using SINPO
codes and collect QSL cards as verification. The article details receiver specifications,
emphasizing selectivity, sensitivity, and stability, with price comparisons from
budget kits to high-end models. Antennas, like long wires or whip antennas, are
crucial...
In response to a controversial article about
Hugo Gernsback's former "employee," Mohammed Fips, and his "Radio
Pen," Dr. Lee de Forest wrote to Radio-Craft magazine claiming he had
invented a similar device decades earlier. De Forest recalled publishing detailed
plans for a miniature radio receiver shaped like a fountain pen as early as 1917-1920,
using Western Electric's "peanut" tube. Radio-Craft verified his claim
by locating the original 1918 Electrical Experimenter magazine article, which described
his pen-sized spy radio. Unlike Fips' later version, de Forest's design required
an external antenna and ground connection. The device used an Audion tube for detection,
tuned via a sliding coil, and was powered by a small battery. Operators concealed
wires in a cane (antenna) and...
"Launched in 1972 by the Soviet Union (USSR),
the spacecraft known as
Kosmos 482 was part of a series of missions bound for Venus. But this one never
made it out of orbit around Earth, stranded there by a rocket malfunction. Much
of the spacecraft came tumbling back to Earth within a decade of the failed launch.
The European Union Space Surveillance and Tracking confirmed its uncontrolled reentry,
based on analysis and no-shows of the spacecraft on subsequent orbits. The ESA's
space debris office also indicated that the spacecraft had reentered after it failed
to appear over a German radar station. It was not immediately known..."
The
tunnel diode, with its unique negative resistance region, excels as an oscillator
and switch. As described by Mr. Queen in this 1960 Radio-Electronics
magazine article, is operating bias is critical - typically around 0.2V for oscillation.
The article details a 27-30 MHz crystal oscillator using a 1N653 diode, requiring
precise voltage division via a potentiometer (R1) and fine-tuning with R2. The load
resistance must be less than the diode’s negative resistance (-40 Ω). A 16-turn
inductor and adjustable capacitor (C2) optimize output. The circuit can self-oscillate
without a crystal but becomes unstable. For switching, the diode's characteristic
curve allows triggering via weak pulses or resistance changes. A light-sensitive
version uses a solar cell in series with a relay - illumination increases...
The 1985 Old Farmer's Almanac clarifies
that Indian
Summer is not just any warm fall day but a specific weather phenomenon marked
by warmth, haze, calm winds, high pressure, and chilly nights, caused by a stalled
high-pressure system trapping dust and smoke near the ground; it must follow a cold
spell or frost and traditionally occurs between November 11 (St. Martin's Day)
and November 20, differing from England's earlier warm spells like St. Luke's
summer. The term's origin is debated - some tie it to Native American beliefs or
autumn foliage resembling Indigenous attire, but the most likely explanation stems
from early New England...
Carl Anderson and Jerry Bishop, John Frye's
techno-teens featured in may Popular Electronics magazine stories, bored during
winter break, decide to invent an "electronic odor killer" called the Meller Smeller
- a helmet with charged screens to neutralize foul smells. Using salvaged TV parts,
they build prototypes with three wire screens: a positively charged outer layer,
a grounded middle layer, and a negatively charged inner layer. The theory is that
odor particles would lose electrons to the grounded screen, then stick to the negatively
charged inner screen. Testing it with a cardboard box reeking of soap and fish proves
inconclusive, so they head to a local soap factory for a stronger challenge. On
the way, they encounter a skunk and foolishly test their...
The "In the Shop ... with Jack" column appeared
monthly in Radio-Electronics magazine, although the title changed occasionally.
In it, Mr. Darr, a celebrated circuits troubleshooter, addressed reader questions
on electronics, offering free troubleshooting help via mail. One inquiry concerned
microvolts per meter (μV/m), a measure of RF field strength. The author clarified
that μV/m represents the voltage induced across a 1-meter wire in free space, aligned
with the transmitter's polarization. Note that μV/m in the case of RF field strength
is NOT a scaling factor for distance form the emitter; it refers to the field strength
induced in a 1-meter length of wire. Hence, a 2-meter length of wire will have twice
the value of a 1-meter wire. This assumes a far field measurement where the wavefront
is planar and at a right angle to the detection wire...
"Researchers have developed an
in-memory
ferroelectric differentiator capable of performing calculations directly in
the memory without requiring a separate processor. The proposed differentiator promises
energy efficiency, especially for edge devices like smartphones, autonomous vehicles,
and security cameras. Traditional approaches to tasks like image processing and
motion detection involve multi-step energy-intensive processes. This begins with
recording data, which is transmitted to a memory unit, which further transmits the
data to a microcontroller unit to perform differential..."
In April of 1961, Yuri Gagarin was the first
human being to "slip the surly bonds of Earth*," and venture into space, to be followed
the next month by Alan Shepard. Just as those flights relied upon data gained from
launching monkeys into space, future manned missions depended on a rapid ramp-up
on methods and machinery needed to extend duration times and safety. Hugo Gernsback's
1964 Radio-Electronics editorial, "To
Remain Alive in Space Is Difficult," underscores the extreme challenges humans
face in the vacuum of space. Earth's atmosphere provides vital protection, but in
space, astronauts must contend with lethal radiation, temperature extremes, and
the constant heat output of their own bodies. A punctured suit means rapid death
as internal pressure causes the body to swell like a balloon. Gernsback highlights...
• Industry Call for
Joint Action on Subsea Cable Security
• Shifting
Sands in Silicon by Global Supply Chains
• $23B
Korea Subsidy to Chip Industry
• EV Making
ICE Engineers
Obsolete?
• FCC
Commish Starks Steps Down
It's a little out of season for posting
this Belmont Radio
advertisement, but it has been on my to-do list for a long time. Back in 1943 when
this full-page promotion appeared in Life magazine, many companies unabashedly
acknowledged America's traditions for celebrating Christmas by including a noel
message in advertisements. Products from military bomber aircraft to washing machines,
to cars, to canned hams were included in the lineup. It was two years into World
War II when this December 27th issue came out, and the theme not surprisingly
focused on our service members who were serving in the fields of Europe and northern
Africa, and in the South Seas. Unlike most of the conflicts our men are involved
in...
In this April 1960 Radio-Electronics
magazine article by the fictitious electronics wizard Mohammed Ulysses Fips (a Hugo
Gernsback pseudonym), the narrator presents the "Paperthin
Radio" - an ultra-thin, lightweight transistor radio designed to undercut Japanese
competition. Built on a stiff paperboard chassis just 1/16-inch thick, the radio
uses standard components cemented into place, with conductive ink for wiring. Key
innovations include a flat ferrite-loop antenna, a modified trimmer capacitor for
tuning, and the "Leptospeaker" - a slim electromagnetic speaker using an Alnico
disc magnet. The two-transistor circuit...
"Claimed to be a world first, the demonstration
took place at Swinhay House. A McMurtry Spéirling
PURE Validation Prototype 1 (VP1) was driven on to a custom-built platform which
then rotated 180 degrees to invert the stationary vehicle. Relying on the huge 'Downforce
on Demand' created by twin 23,000 RPM fans on the car's undercarriage, the Spéirling
remained firmly attached to the platform and was driven a few feet forward before
the rig rotated it back to ground. 'This demonstration was an exciting proof-of-concept
using a small purpose-built rig, but is perhaps just the beginning of what's possible.
With a longer inverted track or a suitable tunnel, we may be able to drive..."
In this 1966 Radio-Electronics
magazine article, Ray Thrower highlights the booming demand for
microwave communication technicians and engineers due to population growth and
industrial expansion. With only 36,000 licensed technicians available nationwide,
the field faces a severe shortage - microwave alone requires 24,000 workers. Companies
prefer microwave over vulnerable cable systems for its reliability, cost efficiency,
and ability to handle high-capacity voice, video, and data circuits. The article
profiles Jim Reeve, a technician trained via military service, and Don Shaffer,
an engineer designing microwave paths, emphasizing hands-on experience and continuous
learning. Entry-level opportunities exist...
This 1964 CREI (Capitol
Radio Engineering Institute) advertisement in Radio-Electronics magazine
served to alert electronics professionals that the Space Age was rapidly transforming
their industry. Automation and advanced aerospace technologies were eliminating
routine jobs while increasing demand for specialists in cutting-edge fields like
space data systems, spacecraft tracking, and aerospace radar engineering. The ad
emphasized that outdated skills could render workers obsolete, but those who upgraded
their knowledge through CREI's home study programs could secure high-demand careers.
Founded in 1927, CREI (now Capitol Technology University) was an accredited home-study
institution that collaborated with NASA and private aerospace firms to design its
curricula. Its Space Electronics Programs were developed with input from government
and industry experts, offering flexible, mail-order education for ele
In this 1968 Radio-Electronics
magazine educational fiction article, high school student Jerry Whipple challenges
Kirchhoff's voltage law in an AC circuit, convinced he's found a flaw. His experiment
measures 7.1 volts across both a resistor and inductor in series, totaling 14 volts
- contradicting the expected 10 V source voltage. His instructor, Mr. Bean,
explains that the discrepancy arises from phase differences in AC circuits: the
voltages are out of phase, not additive. Using a tractor analogy, Bean illustrates
how forces (or voltages) at angles combine vectorially, not arithmetically. He introduces
Pythagoras' theorem to resolve the apparent paradox...
The
G-Line transmission line is another of those things where I can't imagine being
smart enough to come up with the idea, and then implement a working model - like
with the enclosed waveguide. Dr. George Goubau (from whence the "G" in the
name derives) is the genius in this case. He determined that a sort of waveguide
could be made with a single conductor surrounded by insulation with a specific dielectric
constant that would cause the dielectric-air interface to reflect the wave in a
manner similar to atmospheric channels that facilitate long distance communications.
I'm guessing the Surface Conduction company advertising the G-Line for sale in this
1963 issue of Radio-Electronics magazine is Dr. Goubau's enterprise. That was
ten years after inventing it. The G-Line's boasts are low loss (6 dB/mile), no radiation,
and a 300-ohm impedance. The primary disadvantage...
"Let's deal with some common
radiated and conducted emissions immunity issues for the next series of articles.
One that's becoming more prevalent is radiated immunity (or radiated susceptibility,
in MIL-STD-461 terms). It seems this problem has been increasing over the last decade,
and the reasons are threefold: (1) electronic devices are getting smaller and using
plastic enclosure, (2) the proliferation of electronic and body-worn devices has
increased exponentially, and (3) as we're powering circuits with lower voltage levels
(3.3V, or less) resulting in a greatly reduced noise margin. That is, it takes less
energy to disrupt sensitive..."
This 1952 Radio & Television News
magazine article details General Electric's new
G-10 Germanium Dot Rectifier, a high-efficiency semiconductor device for radio,
television, and power applications. Unlike conventional rectifiers, the G-10 avoids
critically scarce materials while offering superior performance - lower forward
resistance, higher back resistance, and extended lifespan. Its design features germanium
pellets sealed in butyl-rubber-insulated metal cups, mounted on aluminum or copper
fins for heat dissipation. Key advantages include 98% efficiency, stable operation
across temperatures (25–75°C), and minimal power loss (under 1 W at 50° C).
The rectifier's low capacitance (20 μμfd) enables use in high-frequency...
This 1942 Life magazine article profiles
a B-17E Flying
Fortress bomber and its nine-man crew, detailing their roles in America's early
WWII air campaign against Japan. The bomber, part of the 342nd Bombardment Squadron,
operates as a self-contained "task force," capable of delivering devastating strikes
like Colin Kelly’s sinking of the battleship Haruna. The crew - four officers (pilot,
copilot, navigator, bombardier) and five enlisted gunners - undergo six weeks of
operational training at MacDill Field to forge teamwork essential for survival.
The B-17E's firepower includes eight .50-caliber machine guns manned by the enlisted
crew...
Exodus Advanced Communications, is a multinational
RF communication equipment and engineering service company serving both commercial
and government entities and their affiliates worldwide. Exodus' model
AMP20016 is a high-performance amplifier designed for EMI/RFI, lab, and communication
applications. Class A/AB linear design, 1000 W minimum with 60 dB gain.
Features advanced linear device technology for wide bandwidth, built-in protection
circuits, and monitoring. Local LCD & remote interfaces for superior control.
High efficiency, rugged reliability. Nominal weight: 40 kg in a compact 5U
chassis...
Mr. E.D. Clark has provided three new
"What's
Your EQ?" puzzlers for your attention, whether you be a student, a theoretician
or just a "practical man." Simple? Double-check your answers before you say you've
solved them. Radio-Electronics magazine ran this feature regularly, and
there is a huge list on the page of the ones I have posted. The invitation for reader
submissions read thusly: "If you have an interesting or unusual puzzle (with an
answer) send it to us. We will pay $10 for each one accepted. We're especially interested
in service stinkers or engineering stumpers on actual electronic equipment. We get
so many letters we can't answer individual ones, but we'll print the more interesting
solutions - ones the original authors..."
|
');
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Homepage
Archives for December 2024. Items on the RF Cafe homepage come and go at a pretty
fast rate. In order to facilitate fast page loading, I keep the size reasonable - under a megabyte (ebay, Amazon, NY Times, etc., are multiple
megabytes). New items are added at the top of the content area, and within a few
days they shift off the bottom. If you recall seeing something on the homepage
but now it is gone, fret not because many years I have maintained
Homepage Archives.
If you believe this 1969
Sylvania General Telephone & Electronics advertisement, you needed only
to stock their specially-designed 60 components to be able to replace every
other component made anywhere in the world. Even in 1969 when semiconductors
were becoming the majority active devices in electronics (replacing vacuum
tubes), the claim is a bit of a stretch. I have my doubts. The ad probably got
posted on a few engineering lab bulletin boards (the physical kind of yore, not
computer BB's) to elicit a few laughs. It reminds me a little of the episode of
M.A.S.H. where a war correspondent asked Captain Hawkeye Pierce what he brought
with him from home, and he responded that he only brought...
Do you know what a soroban is? I have to
admit ignorance prior to reading this 1963 "Carl and Jerry" adventure in Popular
Electronics. As with many of these stories, real equipment, people, and companies
were referenced; this time it was the Pastoriza Personal Analog Computer, a modular
electronics system for calculating differential equations. The cost was around $300
(~$2,700 in c2021 money per BLS Inflation Calculator). Analog Devices bought the
company from James Pastoriza in 1969. What does the Pastoriza computer have to do
with the story, you might ask? Nothing, really; it was mentioned in a discussion
Carl and Jerry had when accepting a calculating speed challenge from obnoxious dormitory
mate, Bruce. Jerry would add a series of numbers on his soroban while Bruce would
add them with a pencil and paper. The winner got bragging rights...
Here is a short tutorial on how to design
a
resistive impedance matching circuit for feeding multiple transmission lines
of equal impedance. Both series and parallel feeds are presented. As the author
mentions, ideally you would like a lossless transformer for matching, but often
a resistive network is acceptable, especially if receive signal power is not an
issue and if your transmitter power is sufficient to overcome the resistive losses
(and doesn't torch the resistors). It is also possible to match transmission lines
of different impedances, but the equation would get messy. Although it would mean
even more resistive loss, the simplest way to match unequal impedance lines is to
first match to a value most of the lines exhibit, then build a separate resistive
transformer for the line(s) that are different to connect between the main match
network and the unequal line(s)...
One aspect of advertising on the RF Cafe
website I have not covered is using
Google AdSense.
The reason is that I never took the time to explore how - or even whether it is
possible - to target a specific website for displaying your banner ads. A couple
display opportunities have always been provided for Google Ads to display, but the
vast majority of advertising on RF Cafe is done via private advertisers. That is,
companies deal with me directly and I handle inserting their banner ads into the
html page code that randomly selects and displays them. My advertising scheme is
what the industry refers to as a "Tenancy Campaign," whereby a flat price per month
is paid regardless of number of impressions or clicks. It is the simplest format
and has seemed to work well for many companies. With nearly 4 million pageviews
per year for RFCafe.com, the average impression rate per banner ad is about 225,000k per
year (in eight locations on each page, with >17k pages)...
Out of the nearly half a hundred quizzes I have
posted from vintage Popular Electronics magazines, this
Semiconductor Quiz that appeared in a 1967 issue is the first I can
remember that was not created by Robert P. Balin. A fellow named Warren Todd
made it. If you are younger than maybe 50 years old, symbols B and I might stump
you, but the rest are still pretty common. Some of the labels (names) presented
in the quiz are a little outdated so I have identified the abbreviations for
you. That will make things much easier. For example, SBS is a silicon
bidirectional switch. Bonne chance...
Per Wikipedia, "A
selenium rectifier is a type of metal rectifier, invented in 1933.
They were used to replace vacuum tube rectifiers in power supplies for electronic
equipment, and in high current battery charger applications. The photoelectric and
rectifying properties of selenium were observed by C. E. Fitts around 1886 but practical
rectifier devices were not manufactured routinely until the 1930s. Compared with
the earlier copper oxide rectifier, the selenium cell could withstand higher voltage
but at a lower current capacity per unit area." Electronics magazines of the era
published many articles about selenium rectifiers...
Just as early cellphones (Motorola's Bag
Phone, e.g.) required large carrying cases to contain both the large electronics
and the large battery required to operate the phone, some of the first commercially
available portable personal radio sets came with shoulder straps. Those that didn't
have straps had wheels and a handle. The "walkie-talkie"
(originally called "handi-talkies") designs were first seen during World War II
and then in Korea. In fact, this 1955 article from Popular Electronics was printed
shortly after the end of the conflict in 1953. Don't confuse the radio-based portable
field telephones with the ones that had a pair of wires (sometimes thousands of
feet of it) that did not need complicated circuitry for over-the-air transmitting
and receiving...
Most of us are likely familiar with the ongoing
debate over whether
radiation from cellphones, Wi-Fi routers and laptop computers, cell towers,
smart meters, and other such modern gadgetry is harmful to humans. It is not
ionizing radiation like nuclear decay, but there are heating effects that can
cause damage under the right conditions. One week news breaks from the latest
organization shocking the public with proof of tissue cell damage to brain,
hand, face, eyeball, and groin tissue (from laptops). The next week brings a
counter report refuting apocalyptic claims of previous studies... then the cycle
repeats. Early in the age of ubiquitous wireless devices, those seeking to
mitigate worries of radiation argued - somewhat correctly - that enough time had
not yet passed to collect statistically meaningful data. If significant harm
could be proven right away, dismissing the empirical results...
Here is a really good introductory article
on electromagnetic
(EM) fields as they pertain to inductors, transformers, and antennas. It appeared
in the April 1942 edition of QST magazine. The FCC had only been in existence for
eight years at the time and was pretty much just figuring out how to regulate the
heck out of everything. The author discusses compliance issues for these newfangled
RF devices that were becoming more and more numerous. Interestingly, the first sentence
says, "Every time you threw the transmitting switch in pre-war days...," bringing
to mind how the Feds banned Amateur Radio during most of World War II for security
reasons as well as to assure that scarce resources went toward building and servicing
military gear as needed. Many Hams offered their gear either as a donation...
With a cover date of August 25, 1945, this
issue of The Saturday Evening Post obviously went to print some time prior
to the dropping of the two nuclear bombs on Japan that ended World War II. Victory
in Japan Day (V-J Day), was August 14, 1945. There is no hint inside the magazine
that the end of the war was nigh. There were, however, plenty of ads by companies
touting their contributions to the war, and even some ads, particularly food ads,
anticipating the end of rationing. Within this edition is also a short quiz entitled,
"How's Your Radio Knowledge?" The author, Captain James F. C.
Hyde, Jr., challenges readers to identify the locations of radio stations just
by looking at their call signs. As is done today, most stations attempt to get
call signs that are relevant to their location...
$5,000 in 1956 currency is equivalent to
about $46,000 in 2020, per the U.S. Bureau of Labor Statistics' "Inflation Calculator."
That is the value of the amateur radio equipment used by
Mrs. Mary Burke in her work handling "an average of 3000 messages per month,
principally for service personnel overseas." For her tireless wireless efforts,
she was the first woman to win the coveted Edison Award Cup (sponsored by General
Electric). Most of Mrs. Burke's communications was via Morse code, where she restrained
herself to "about 30 words a minute to maintain accuracy". Way to go, Mary!
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. In this crossword
for June 14th 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 Lamarr or the Bikini Atoll, respectively.
Enjoy!
Precision Ruggedized VNA Cables from ConductRF
offer RF Engineers great alternatives to costly OEM cables that are now past their best
days. We have many standards for applications at 18 GHz, 27 GHz and 40 GHz.
Our torque resistant connector heads and phase stable constructions ensure great performance
for many tests to come. ConductRF
VNA series provides customers with reliable ruggedized solutions for lab and
production VNA testing...
The concept of a
field effect transistor (FET) has been around in theory for a
long time*, but manufacturable devices arrived in designers' labs not until the
early 1960s. This article from the October 1966 edition of QST magazine
gives a good introduction to the physics of a basic FET as well as the junction
FET (JFET) and the insulated gate FET (IGFET), all of which are still in
widespread use today. What you learn about them here is applicable today. In
fact, I swear some of the drawings are the same ones that appeared in my college
semiconductor physics text books (admittedly from the late 1980s, so not too
much of a surprise)...
Ed Troy, owner of Aerospace Consulting, was
kind enough to offer a few of his articles for posting on RF Cafe. With more than
30 years in the electronics communications design field, Ed has a lot of valuable
knowledge to impart to us mortals ;-) This third paper demonstrates why using a
highly capable software simulator for system design work is essential because of
its ability to predict and facilitate mitigation of system-generated problems prior
to building and testing the prototype. Case in point are
spurious spectral components generated by the local oscillator and SSB to PM
conversion created in a frequency doubler circuit. This paper was adapted from an
example circuit provided in Keysight (formerly Agilent) Genesys Spectrasys. Spectrasys
is a spectral domain block diagram simulator that allows the user to construct a
system model and quickly determine the system performance. Whether you are involved...
Summer begins this week in the northern hemisphere,
and winter begins south of the equator. Counterintuitive to northerners not familiar
with the geometric cause of seasons (axis tilt) is that the Earth is actually closest
to the sun in January than it is in July. Our orbital path is nearly circular, with
an eccentricity of just 0.0167. Anyway, I thought the onset of summer would be a
good time to post this installment of
Mac's Radio Service Shop entitled, "Summer Seminar." Typical of author John
Frye's techno-sagas, more than one theme runs through the story. It begins with
shop owner Mac admonishing technician Barney for throwing away a faulty selenium
rectifier when he knows there is an industry-wide shortage on supplies of the element
and the bad components should be submitted for recycling. Fretting over as common
an element ...
"Tokyo is now a next-door neighbor-thanks
to the magic of short-waves." That statement was made in a 1935 edition of Short
Wave Craft magazine after the American Telephone and Telegraph (AT&T) company
completed its wireless phone (voice) link between the U.S. and Japan; which is the
first 'T' in AT&T. Most people today would probably have a hard time guessing
that the
second 'T' in AT&T stands for 'telegraph.' Its surprising that the name
has not been changed to reflect the outdated-ness. Western Union sent its final
telegraph in 2006. Another news headline a couple years ago reported on India sending
its final official telegraph message...
Electronics has dominated our lives ever
since the first commercially available radios became available in the early twentieth
century. It was a mysterious miracle science then and still is today. Most people
have no understanding of electronics; they just know that life without it is unimaginable.
Fantastic new applications for electronics are continually being introduced to supplement
or replace mechanical devices. Sensing and control are prime applications for electronics
that improve functionality and safety. This promotion of the MIT-Sperry Detonation
Indicator, aka the "Knock-O-Meter,"
is a good example. It appeared in a 1945 issue of Radio-Electronics magazine, near
the end of World War II. Today, such a name invokes chuckles and usually implies
a joke of a product, but not so at the time...
Image response, harmonic of the IF, direct
IF response, harmonics of the oscillator, combination of the IF, heterodyne oscillator
radiation, cross modulation within the receiver, cross modulation external to the
receiver, same channel beat, adjacent channel beat and "monkey
chatter" are all sources of radio interference addressed in this article that
appeared in a 1946 edition of Radio News. I don't know about you, but I've never
heard of the term 'monkey chatter.' According to the troubleshooting table it is,
"Unintelligible modulation superimposed upon desired station, having the character
of 'inverted speech'." Recommendations on how to mitigate "monkey speech" are provided...
It's hard to imagine a time when
unlicensed radio frequency bands were not the norm, but early
in the history of radio, strict spectrum control was necessary in order to prevent
unintentional radiation from crappy equipment from interfering with services. Remember
that even in the mid 1940s, many, if not most, casual users were cobbling together
their own transmitters and receivers from scratch. Transmitter powers were easily
high enough to interfere with nearby and distant receivers, but even improperly
shielded receiver oscillator ("exciters") could cause interference with a neighbor's
nightly Lone Ranger broadcast. Around 1945, the FCC began entertaining the idea
of allocating bandwidth for the use of the newfangled "walkie-talkies" that were
developed for field communications during World War II. This 460 to 470 MHz band
was the first of the Citizens' Bands that eventually... |