|
 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..."
|
 Werner von Braun and his team of rocket scientists
are credited with developing the first useful inertial stabilization platforms for
ballistic missiles. The infamous and formidable V2 rocket wreaked terror upon the
heads of Londoners during the latter days of World War II. It served to keep
the rocket in a fixed orientation during the boost phase of the flight, but did
not serve any active targeting function.
Inertial navigation systems, on the other hand, are used to provide both accurate
positional and attitude information for the pilot (if the platform has one) and
to steer the platform (vehicle) to a predetermined destination. Inertial navigation
systems are therefore much more complex. Early inertial navigation systems relied
on physical spinning gyroscopes mounted within a series of nearly frictionless gimbals
to maintain a fixed reference position in space. Contactless encoders about the
rotation axes of the gimbals sent positional information to a computer, which then
performed necessary calculations and sent formatted data to visual flight instruments...
 This
electronics analogy quiz is a little easier than many of the others
published in Popular Electronics magazine because all of the electrical
and mechanical objects depicted here are very familiar. The concepts might seem
trivial to those of us who have been immersed in the science for decades, but I
for one can remember when first hearing these analogies how helpful they were.
Not only that, but I also recall during physics and mechanics courses in college
being amazed at the similarity of equations shared by electrical and mechanical
processes. Wikipedia has a huge page describing many of the most familiar
mechanical-electrical analogies...
 Radio-Electronics magazines' "Service
Digest" column regularly reported on issues relevant to the electronics servicemen
who repaired radios, television sets, phonographs, recorders, and similar items
- often in the customers' homes. Then, as now, professionalism and courteous behavior
was often rewarded with word-of-mouth referrals to friends and relatives, resulting
in new business opportunities. An interesting topic also included was the need to
observe extreme caution when working around TV tubes (CRT's) not just because of
the lethally high voltages present, but because of the
danger of tube implosion and the resulting scattering of glass shards. An example
given is that due to standard atmospheric press of 14.7 lbs/in2 on the outside of
the evacuated volume, a 17-inch screen CRT tube supports a total pressure of 3,322
pounds, or 1.66 tons...
 This is a great example of how Popular
Electronics and John T. Frye used the "Carl &
Jerry" series to teach some basic electronics design principles through story
telling. The same is true with his long-running "Mac's Service Shop" series of techno-dramas.
In this adventure, the the two teenagers decide to build a tachometer from schematics
they found in a magazine. They debate amongst themselves how the circuits works,
the best way to assemble the circuit, component selection, vibration-tolerant mounting,
and how to properly calibrate the tach to accurately display engine revolutions
per minute (RPM). Being set in 1960, this is one of the first appearances of transistors
in circuits rather than vacuum tubes. Transistors were still very mysterious - and
even detested - by many electronics hobbyists and professionals, so pieces like
this...
 You've heard of
"Litz" wire, right? It's the twisted bundle of multiple enamel
or otherwise coated wire used for making couplers, antennas, and at frequencies
up to about a couple MHz. Congratulations, but did you know the full name for it
is "Litzendraht?" Neither did I until after reading this article. Litzendraht does
not derive from the surname of a fellow named Otto or Wolfgang Litzendraht, but
is the German word meaning "braided wire" or "woven wire." Litzen by itself means
braided or stranded. So, technically if you call it Litzendraht wire, you are being
redundant since it is the same as saying woven wire wire. That might save you some
embarrassment one day if you happen to be working around a German techie. Litzendraht
is used in order to exploit the skin effect at high frequencies where the majority
of the current is conducted on the wire's surface. Using multiple insulated wires
enables greater current carrying capability...
 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...
 Today's electronics and RF magazines tend
to cater to engineers and managers, as opposed to technicians and hobbyists. That's
not to say that techs do not benefit from the material presented, but that information
is typically concerned with new product and system design with little attention
paid to troubleshooting and maintenance. The predecessors to modern magazines much
more often included articles on the latter. Publications like Popular Electronics,
being intended for hobbyists, featured useful quizzes, "how to" articles, and troubleshooting
tips along with product reports and an occasional design methodology piece.
Electronics World, the predecessor to Popular Electronics, was more
of an equal split between professional and hobby themes. This particular article
tests the reader's
knowledge of capacitors by proposing circuit failure
examples...
 A
"V" Antenna is a bi-directional antenna used widely in military and commercial
communications. It consists of two conductors arranged to form a V. Each conductor
is fed with currents of opposite polarity. The "V" is formed at such an angle that
the main lobes reinforce along the line bisecting the "V" and make a very effective
directional antenna (see figure 4-35). Connecting the two-wire feed line to the
apex of the "V" and exciting the two sides of the "V" 180 degrees out of phase cause
the lobes to add along the line of the bisector and to cancel in other directions,
as shown in figure 4-36. The lobes are designated 1, 2, 3, and 4 on leg AA', and
5, 6, 7, and 8 on leg BB'. When the proper angle between AA' and BB' is chosen,
lobes 1 and 4 have the same direction and combine with lobes 7 and 6, respectively.
This combination of two major lobes from each leg results in the formation of two
stronger lobes, which lie along an imaginary line bisecting the enclosed angle...
 If my counting is correct, by 1952 only 33
of America's 48 states (Hawaii and Alaska weren't admitted until 1959), and Washington,
D.C., had
television broadcasting stations. That most of the early television
experimentation occurred on the east coast is apparent by looking at the number
of stations there compared to the west coast. You might think California would
have the largest amount of TV stations, but it only had 11 located in 3 cities.
New York, on the other hand, had 13 in 7 cities. Ohio had 12 stations in 5
cities, and Pennsylvania had 7 stations in 5 cities, one of which was my town of
Erie. Vermont, New Hampshire, Mississippi, Wyoming, both Dakota, and Oregon were
among those with no television stations by 1952. That seems unbelievable since
that was only 67 years ago, but evidently was so. The network "lines" included
microwave repeaters to reach from coast to coast. On September 4, 1951, AT&T
opened the network by televising a presidential address...
 Until solid state electronics had supplanted the
majority of vacuum tube type televisions and radios,
portable tube testers were essential equipment to successful, efficient troubleshooting
and repair in businesses and people's homes. Yep, believe it or not the stories told
about doctors and electronics repairmen visiting homes are not just fables. I remember
as recently as the 1960s having our family doctor make house calls when I or one of my
fours sisters got sick. Both doctors and TV servicemen ceased the practice at about the
same time - probably the result of a Brotherhood of Electronics Technicians and General
Practitioners collective bargaining agreement ;-) Many column inches of editorials, articles,
comics, and letters to the editor were devoted to the trials and tribulations of in-home
servicemen and the experiences...
 A year has passed since I last posted a
Carl and Jerry high-tech saga. John T. Frye created the duo of teenage
sleuths in 1954 for the very first issue of Popular Electronics magazine. More than 100
adventures carried Carl and Jerry from high school through college. Their practical jokes,
crime solving, and mystery investigations incorporated microphones, timers, cameras,
Ham radio, transformers, metal detectors, remote controllers, home brew circuits, photodetectors,
and a host of other gadgets that could be pulled from a stash of parts in Carl's or Jerry's
basement workshop, or borrowed from a friend. In this story, Carl and Jerry, now students
at Parvoo University in Indiana, have an unexpected confrontation with a radio operator
while exploring a campus...
 This exercise would make a good laboratory experiment
for high school or junior college electronics courses. The required components are still
readily available - Borax is in the cleaners aisle of the grocery store. In the days
before vacuum tubes, when scientists had a need to
rectify alternating current power supplies they used chemical devices similar to
the one described here. Ironically, this chemical rectifier is a form of semiconductor
diode; albeit in a liquid state rather than in the eventual solid state. Note that the
rectifier symbol in the schematic is actually the chemical device created in the first
step - not a vacuum tube as it might appear to be...
 RF, IF and baseband amplifiers; RF, IF, and
baseband filters; fixed and tunable local oscillators, single- and double-balanced
mixers, attenuators, envelope detectors and phase detectors, directional couplers,
power combiners and dividers, et cetera, are all component types used for
receiver systems regardless of whether vacuum tubes or transistors
comprise the active parts. In 1972 when this article appeared in Popular Electronics
magazine, people were beginning to get comfortable with the idea of transistorized
products replacing the familiar tube. Instant-on televisions and radios were...
 Prior to the availability of affordable
synthesized transceivers under microprocessor control, Ham radio operators needed
to tune a continuously variable local oscillator (internal or external) or have
a selection of crystals for specific frequencies. Even by 1982 microprocessors were
relatively expensive, so equipment incorporating them was also pricey. Heathkit's
model
SS-9000 transceiver claimed to be designed by amateurs for amateurs, and was
"so feature-conscious, it has no options." That's right, anything and everything
that could be imagined was included in the base model; there we no upgrades. It
used a high accuracy and stability internal 10 MHz reference oscillator for
the PLL synthesizer. Also incorporated was an RS-232 serial port for control via
computer (up to 9600 baud!), such as the Heathkit/Zenith personal computer (the
IBM PC had hit the market in the prior year, and the the Radio Shack TRS-80
and Apple II had been around since 1977). The SS-9000 was solid state throughout
(likely where the "SS" prefix originated)...
 It was only the first day at engineering
college and already their first familiar techno-caper was underway. Indiana's Parvoo
University was about to get an initiation into the world of
Carl Anderson and Jerry Bishop, who during their high school years together
solved many a mystery and pulled many a prank in their hometown somewhere in northern
Indiana. As with all of John Frye's tales this one mixes serious electronics topics
with a bit of fun and a life lesson. There were no 'bad guys' here as in many other
episodes, but the boys did get an unexpected introduction to Parvoo U.'s president!
Despite the story's title, the day ended well ...
 Selecting the proper antenna for a particular
application can mean the difference between success and failure when any combination
of signal strength and/or signal interference is involved. Modern spread spectrum
technologies has eased the job a bit, but there are still instances when high gain
and/or directivity is necessary. You might be tempted to say that gain and directivity
are essentially the same thing, and to some extent that is true. However, in the
case of needing to minimize signal interference from surrounding sources, a
directional antenna might be utilized not due to a need for increased
desired signal strength but to reduce the power of undesired emitters. Such was
often the requirement for television and FM radio reception. After years of needing
to reorient the folded dipole antenna for my FM radio because...
 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...
 The newest release of RF Cafe's spreadsheet
(Excel) based engineering and science calculator is now available -
Espresso Engineering Workbook™. Among other additions, it now has a Butterworth
Bandpass Calculator, and a Highpass Filter Calculator that does not just gain, but
also phase and group delay! Since 2002,
the original Calculator Workbook has been available as a free download.
Continuing the tradition, RF Cafe Espresso Engineering Workbook™ is
also provided at no cost,
compliments of my generous sponsors. The original calculators are included, but
with a vastly expanded and improved user interface. Error-trapped user input cells
help prevent entry of invalid values. An extensive use of Visual Basic for Applications
(VBA) functions now do most of the heavy lifting with calculations, and facilitates
a wide user-selectable choice of units for voltage, frequency, speed, temperature,
power, wavelength, weight, etc. In fact, a full page of units conversion calculators
is included. A particularly handy feature is the ability to specify the the number
of significant digits to display. Drop-down menus are provided for convenience...
 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 adopted in an attempt
to report the work done in the years where there is a dearth of readily available
published material...
 "The perfect squelch" was a popular concept
in the 1950s. I know because I've seen it in a few different magazines from that
era. In fact, The Saturday Evening Post ran a regular inset feature by that name.
As you might guess, it has to do with making a short statement that has the effect
of cutting out the 'noise,' whether it be from the background of a radio reception
or from an obnoxious person shooting off his mouth (which was the case for the SEP).
BTW, the "Squegg" part of
Sunspot McSquegg's name comes from the radio term 'squeg,' which refers to
oscillations due to excessive feedback, like what happens when a microphone is
placed too close to the speaker. This Christmastime tidbit appeared in the
December 1953 issue of QST magazine... |
