 Thursday the 28th
 I finally got around to scanning selected
content from the 1986 issue of The Old Farmer's Almanac. The "Old and New Mathematical Puzzles" feature was always my favorite,
so that's what is posted first. Difficulty levels are assigned as 1 for the easiest
to 5 for the hardest. Solutions are provided for levels 1 through 4, but level 5
(problems 12 through 15) problems were to be mailed in (no e-mail in the day) to
vie for a cash prize for providing the "best set of solutions," though I don't know
how one solution to these problems can be deemed "better" than another. Problem
#5 is interesting in that you must assign a value for the various numerical prefixes
and quantities. Sure, we all know what "atto" and "score" are, but what about "crore"
and "myriad?"
 Sam Benzacar of
Anatech Electronics, an RF and microwave filter company, has published
his January newsletter that features his short op−ed entitled "In a Digital World,
Analog Filters Stand Their Ground." It points out that with few exceptions, even
the most sophisticated digital RF systems require some form of analog filter at
the input (receiver) or output (transmitter). Power levels and aliasing components
of sampled systems keep digital (software) filters from being used universally.
That bodes well for the world's analog filter companies, including Anatech. Sam
also presents some relevant industry news items as well...
 "Coffee
is one of the most widely consumed beverages in the U.S. and worldwide. Americans
consume
400 million cups per day, making the U.S. the world's leading
consumer of coffee. E-commerce and coffee go hand-in-hand. As the market grows -
and becomes more competitive - coffee companies are coming up with more creative
ways to get their products to online consumers. The E-Commerce Times recently spoke
with coffee and e-commerce experts to get their views on what's involved in successful
online coffee sales. Selling coffee online was very popular even before the pandemic
hit, which, of course, increased demand for all goods online..."
 MKS Instruments is a global provider of instruments,
subsystems and process control solutions that measure, monitor, deliver, analyze,
power and control critical parameters of advanced manufacturing processes to improve
process performance and productivity for our customers. We currently have
an opportunity for an experienced
Switch Mode RF Power Generation Designer. Are you naturally curious?
So are we at MKS. Our collective curiosity drives us to be an innovation leader
in many industries. Our products drive technology advancements across a wide range
of applications such as 5G, augmented/virtual reality, autonomous vehicles, clean
drinking water and space exploration. This R&D position focuses on high performance
RF power generation equipment used in state-of-the-art plasma processing tools.
Switch mode RF power amplifier (e.g. Class D) circuit/system design, simulation,
and testing...
 When you look at the circuit board and/or
chassis of a
radio set - new or old - you see a lot of components including
resistors, semiconductors (and/or vacuum tubes), inductors, capacitors, transformers,
switches , potentiometers, shielded cables, shielded compartments, displays, indicator
lights, connectors, etc. With the possible exception of some semiconductors (ICs
and discretes), the function of just about every component can be discerned by most
people who are at all familiar with radio electronics by its location in the circuit,
with the exception being inductors and transformers (other than those in the power
supply). Inductors and transformers tend to be the least understood and therefor
the most mysterious. They are the least likely to bear any identifying marking unless
they happen to be encapsulated like a resistor or capacitor. Articles like this
one help remove some of unknowns...
 Spectrum Instrumentation extends its range
of hybridNETBOX products with the addition of eight high-performance models. The
hybridNETBOX is an innovative instrumentation platform that combines a multi-channel
arbitrary waveform generator (AWG) and a digitizer in a single portable unit. With
their unique capability for simultaneous signal generation and acquisition, these
powerful tools are perfect for applications involving stimulus-response or closed-loop
type testing. In total,
14 different hybridNETBOX models are available now, with 2+2,
4+4 or 8+8 matched channels and possible speeds from 40 MS/s to 1.25 GS/s. The new
models offer a choice of two or four AWG channels...
 PCBONLINE supplies complex rigid and flex-rigid
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efforts, PCBONLINE constantly updates our equipment, improves our technology, and
serves you with the highest quality. Cost and delivery quotations online without
the need for multiple phone call and/or e-mails.
Wednesday the 27th
 RF Cafe visitor Vince S. saw the "Barney
Turns Inventor" episode of "Mac's Radio Service Shop" series recently posted here
which told of Barney's idea for a vacuum tube tester that would set all the switches
and voltages based on a coded card for the particular tube type. That story appeared
in a 1950 issue of Radio & Television News magazine. I don't know when Hickok
came out with their first
"Cardmatic" tube tester, but as Vince noted in his message to
me, the idea might have been borne of John Frye's fictional scenario. This
full-page advertisement for the Hickok Model 121 High-Speed Portable Cardmatic Tube
Tester comes from the March 1958 issue of Radio & TV News. A YouTube
video of a Model 121 Cardmatic is included below...
 "Why do some thin films of single-wall
carbon nanotubes take on colourful hues even though as-synthesized films
are usually black? A team of researchers in Finland, the US and China has now come
up with a possible answer in a development that could prove useful for future display
screens and solar cells. Single-wall carbon nanotubes (SWCNTs) are rolled-up sheets
of carbon just one atom thick, with a diameter of about 1 nm. Atoms in these sheets
are arranged in a hexagonal lattice and the direction in which the sheet is rolled
- its chirality - dictates whether the tube is a metal or a semiconductor. When
these SWCNTs are sorted by their diameter or chirality - two traits denoted by an
'(n,m)' numbering system..."
 Ken G. recently wrote to request that his
company, TechnoTronix Electronics
Manufacturing Services, be added to the following Vendor pages on RF Cafe: Contract
Manufacturing, Electronic Assembly, Product Design & Development, and Substrate &
PCB Fabrication & Assembly. Says Ken: "TechnoTronix has been active for the
past 40 years in making the best printed circuit board assembly. We are an ISO 9001:2015,
ISO 13485:2016 & AS9100 Rev. D certified PCB Assembly company who fulfills all
your PCB needs in minimum time. We use the latest technologies like Plated Thru−Hole
(PTH) and Two−Surface Mount (TSM) and find smart ways to provide the best printed
circuit board assembly services in California."
 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...
 Skyworks is pleased to introduce a complete
family of
high-efficiency power amplifiers (PAs) designed for the stringent
requirements of enterprise small cell radios, including 4G LTE and 5G NR. These
devices offer wide instantaneous bandwidth with high gain and are fully input/output
matched. Active biasing circuitry is integrated to compensate for PA performance
over temperature, voltage, and process variations. With a compact 5 x 5 mm package,
the SKY663xx−11 family of PAs is ideal for 5G systems operating from 2.3 to 5 GHz...
 Nova Microwave is a leader in technically
differentiated electronic and radio frequency Ferrite
Circulators
and Isolators that connect, protect and control critical commercial and military
wireless telecommunications systems. Our staff is dedicated to research and development
of standard and custom design quality Ferrite Circulators and Isolators from 380 MHz
to 26.5 GHz. Available in single or multi-junction topographies, the Nova Microwave
product line of is specifically designed for use in varied environmental and temperature
extremes.
Tuesday the 26th
 Quite a few articles on
color television were published in trade and hobby magazines in
the 1950s and 1960s as the technology was adopted and fine tuned. The electronic
circuitry aspect of transmitting and receiving chromaticity, intensity, synchronization,
and audio was impressive, but the science that went into color research was equally
amazing. As with so many things we take for granted because someone else did all
the hard work of figuring out how to make something work and then making it available
to us at an affordable price, the physics of human color perception needed intense
study in order to produce a pleasing image on the cathode ray tube (CRT). The key
to understanding color is the chromaticity diagram, based in the human tristimulus
color space, which is described in detail herein...
 Enhanced mobile broadband (eMBB) services
in 5G/6G communications systems will extend the current mobile experience by providing
massive connectivity to the internet with extreme capacity, coverage, reliability,
and ultra-low latency. A new "5G NR Design for eMBB" white paper showcases the unique system
and circuit capabilities in Cadence® software that overcome eMBB design challenges.
A 28 GHz receiver integrated circuit (IC) and phased-array reference design
is presented in which the capabilities of AWR Design Environment®, Virtuoso® RF
Solution, EMX® Planar 3D Solver, and Allegro® PCB Designer software were combined
to develop the RFIC receiver, package, and board with embedded antenna array...
 "EPFL engineers have developed a computer
chip that
combines two functions - logic operations and data storage - into
a single architecture, paving the way to more efficient devices. Their technology
is particularly promising for applications relying on artificial intelligence. It's
a major breakthrough in the field of electronics. Engineers at EPFL's Laboratory
of Nanoscale Electronics and Structures (LANES) have developed a next-generation
circuit that allows for smaller, faster and more energy-efficient devices—which
would have major benefits for artificial-intelligence systems. Their revolutionary
technology is the first to use a 2-D material for what's called a logic-in-memory
architecture, or a single architecture that combines logic operations with a memory
function. The research team's findings appear today in Nature..."
 Only a couple decades prior to when this
article on a newfangled
wireless automatic garage door opener appeared in Radio-Craft
magazine, there would have been no demand for such a device ... although maybe an
automatic horse barn door opener would have been in demand if a battery was available
on the coach. Amazingly, the system employed an early, albeit crude, form of both
spread spectrum and digital communications in order to trigger the receiver for
opening the door. The spread spectrum characteristic of the signal was the natural
consequence of using a spark transmitter. A digital 'Morse' code encryption allowed
multiple openers to be installed in close proximity. The opener did not have any
type of safety sensor to prevent people or things from being crushed, but then it
wasn't until sometime around the 1970s that the feature became standard...
 It has been a while since I saw an article
discussing stability circles for amplifier design. Ain Rehman has one posted on
the High Frequency Electronics website entitled, "Understanding Stability Circles." Even in the age of computer
design and optimization for just about everything, it always help to have a basic
understanding of what the result should look like as well as what affects the result.
He begins: "Stability circles are a tool, used to examine and analyze the stability
of an amplifier (in the case under discussion) using a graphical technique, with
the help of a Smith Chart. This monograph presents the stability circle tool for
engineers. It is understood that many CAD programs can generate these, but it is
always useful to understand the stability circle on an intuitive level as a good
engineering practice..."
 PCB Directory is the largest directory of
Printed Circuit Board (PCB)
Manufacturers, Assembly houses, and Design Services on the Internet. We have listed
the leading printed circuit board manufacturers around the world and made them searchable
by their capabilities - Number of laminates used, Board thicknesses supported, Number
of layers supported, Types of substrates (FR-4, Rogers, flexible, rigid), Geographical
location (U.S., China), kinds of services (manufacturing, fabrication, assembly,
prototype), and more. Fast turn-around on quotations for PCB fabrication and assembly.
Monday the 25th
 I learned a new word from this Radio-Craft
article: "chemurgic," which refers to chemurgy, the science of creating products
such as soybean gear shift knobs and cellulose movie film from agricultural raw
components. It has nothing to do with the story other than to describe the town
in which the subject, Wesley Rushing, lived. As the title suggests, Mr. Rushing
established and thrived at a
radio repair business built while confined to bed with a crippling
illness. He worked an average of 10 hours per day and repaired two hundred radios
each month. Although not a veteran himself due to his sickness, the story was offered
as a means of support to the thousands of returning World War II veterans who
suffered disabilities in battle. Today's handicapped veterans need and deserve similar
encouragement, so if you have a can-do story, please submit it to one of the trade
or hobby magazines; it will be greatly appreciated by many...
 "Shawn Prestridge, Lead FAE Engineer and
U.S. FAE Team Manager at IAR Systems offers his insights and predictions about
embedded development - the technology, markets, and tools - in
2021. We've seen R&D groups at large customers dabble with RISC-V to see if
they want to base a platform on it, and we've seen smaller customers start to use
it. A few large companies have really committed to using it in at least some business
units. While part of the RISC-V trace specification was ratified this past February,
there will still be a few tweaks made in 2021. Ultimately, you'll see a good deal
of high-quality debug information like live instruction trace, interrupt visibility,
power usage, and other metrics that can be fed through the debug port. Amongst other
things, this will truly empower embedded developers to produce..."
 Carl Novello has an interesting article
on the Electronic Design website entitled, "Gain Efficiency with Fragmented-Aperture Phased Arrays." I've
always been skeptical of repetitive, pixelated type antenna patterns like the use
of fractals and the seemingly random pattern (but probably computer optimized -
looks
 like shapes from
Space
Invaders) used here. Evidently, there is something to it, though. He begins:
"The world's demand for broadband connectivity has created a new generation of high-throughput
satellites in geosynchronous Earth orbit (GEO), medium Earth orbit (MEO), and now
low Earth orbit (LEO). But technology innovation in the ground segment has struggled
to catch up to the space segment, especially when it comes to developing the most
elusive of all antennas: Those that are low-cost and electronically steerable to
power these next-generation, lower-orbit satellite networks. Electronically steerable
antennas (ESAs), often referred to as flat panels..."
 Anyone visiting RF Cafe (other than by
accident) almost certainly knows of Drs. Bardeen, Brattain and Shockley fame for
their
transistor invention while jointly working at the Bell Telephone
Laboratories. The trio shared The Nobel Prize in Physics in 1956. Bell was so proud
of their employees' efforts that they ran full page advertisements to boast of the
accomplishment. This one appeared in the February 1957 edition of Radio &
Television News. Alas, Ma Bell's moment of glory was a bit diminished by needing
to add a footnote admitting that Drs. Bardeen and Shockley no longer work there.
Note that while the ad says the transistor was announced in 1948, the first demonstration
to Bell managers was in December of 1947...
 This story, submitted by RF Cafe visitor
Jerry L., of Cincinnati, OH, reminds me of a certain manager in a popular engineering
comic strip. Do you have a good work-related anecdote to share in the "Out of Order" feature? Please email it to me for consideration.
Jerry Writes: "I worked in the defense electronics industry for my entire career
and it is hard to think of a project in more than four decades that was not made
infinitely more difficult due to the 'helpful' input of project managers. One experience
in particular comes to mind as a perfect topic for your Out of Order feature. In
the mid 1970s I was a "fresh-out," as new engineering college graduates were called
at the time. Newly minted as a Masters degreed electrical engineer, my aspirations
were high and I was ready to set the mobile radio system world on fire. A synergistic
combination of my own zeal and aptitude (I earned my Ham license at age 16) with
that of a seasoned engineer mentor...
 Empower RF Systems is a global leader in
power amplifier solutions. Empower RF Systems is an established and technologically
superior supplier of high power solid state RF & microwave amplifiers. Our offerings
include modules, intelligent rack-mount amplifiers, and multi-function RF Power
Amplifier solutions to 6 GHz in broadband and band specific designs. Output
power combinations range from tens of watts to multi-kilowatts. Unprecedented size,
weight and power reduction of our amplifiers is superior to anything in the market
at similar frequencies and power levels.
Sunday the 24th
 This Science Theme crossword puzzle for
January 24th contains only words and clues related to engineering, mathematics,
chemistry, physics, and other technical words. As always, this crossword contains
no names of politicians, mountain ranges, exotic foods or plants, movie stars, or
anything of the sort unless it/he/she is related to this puzzle's technology theme
(e.g., Hedy Lamarr or the Bikini Atoll). The technically inclined cruciverbalists
amongst us will appreciate the effort. Enjoy!
Friday the 22nd
 The January 1951 issue of Radio-Electronics
magazine had a big collection of
electronics-themed comics - five of them. All of them are pretty
good, and you don't need to have been there during the early TV era to appreciate
the humor. The comic from page 127 is a good first step in troubleshooting for today,
and is usually at the top of the problem solving section of consumer gear throughout
the electronic age. The page 126 comic is an oft-used gag for garage-related funnies.
Although not directly related, it reminds me of how early wireless garage door openers
had their antennas stretched underneath of the car...
 All
RF Cafe Quizzes make great
fodder for employment interviews for technicians or engineers - particularly those
who are fresh out of school or are relatively new to the work world. Come to think
of it, they would make equally excellent study material for the same persons who
are going to be interviewed for a job. This quiz is based on the information presented
in Multi-Gigabit Microwave
and Millimeter-Wave Wireless Communications, by Jonathan Wells.
 "Characterizing
microstrip superconducting film at millimeter-wave frequencies
is difficult without undergoing a complex thin film fabrication process. This characterization
includes measuring the ohmic loss at a resolution of 10100 parts per million (ppm).
Typically, characterizing microstrip superconducting film utilizes antenna-coupled
bolometers as part of the superconducting film structure. Bolometers are components
that measure incident electromagnetic radiation via the heating of a material with
a temperature-dependent electrical resistance; however, this process is disadvantageous
as embedded detectors, such as bolometers, make the superconducting film fabrication
process more difficult. This process also requires various millimeter-wave components,
further complicating film fabrication. Additionally, characterizing superconducting
film..."
 In 1945, when this article was published
in QST magazine, radar was still in its infancy. Engineers were already
aware of the need to shape pulse waveforms from experience with CW keying and the
need to mitigate the effects of "chirping." A perfectly rectangular pulse in the
time domain, as we learned in our signals and systems courses, creates a
sin (x)/x response in the frequency domain. The Fourier transform
shows that a perfectly square pulse in the time domain is the summation of an infinite
number of odd harmonics of the fundamental (1st harmonic). The first few harmonics
are audible to the CW copier as higher frequency "chirps." To reduce the annoyance
(and wasted transmitted energy), time constants were added to the leading and trailing
edges of the waveform to remove the higher frequencies, while leaving the pulse
shape sufficiently rectangular to achieve its goal. The same type issue applies
to radar pulses...
 Here's
a trip down Memory (640 kB) Lane for those of us around during the early PC
days, using MS−DOS. EDN magazine has been running their column "Tales from
the Cube" (a take-off of the equally long ago "Tales from the Crypt" TV show)
where readers submit sagas of (usually) troubleshooting experiences. Most often
the problem is the result of an intermittent event or of human error (pronounced
"stupidity"). This is a case of the latter. If you fondly recall the times when
256-color VGA CRT monitors,
3½" floppy disks, 20 MB hard drives, and an
i80287 math
coprocessor were to die for, when you were deemed a computer expert if you could
write batch files, and half your computer's CPU power was not consumed by antivirus
programs (no WWW, just
Kermit
for local net access), then you might like this "The Mysterious
MS-DOS Reboot" anecdote by Robert Yankowitz. Enjoy!
 RF
Cafe's raison d'être is and always has been to provide useful, quality content for
engineers, technicians, engineering managers, students, and hobbyists. Part of that
mission is offering to post applicable job openings. HR department employees and/or managers of hiring
companies are welcome to submit opportunities for posting at no charge. 3rd party
recruiters and temp agencies are not included so as to assure a high quality of
listings. Please read through the easy procedure to benefit from RF Cafe's high
quality visitors...
 Axiom Test Equipment allows you to
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