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5 of the September 2020
homepage archives. Wednesday 30
 Selenium rectifiers were the first widely
used as other-than-vacuum-tube circuit elements for various power supply designs.
They were not very practical as detectors in receiver circuits unless signal levels
were high. Properly manufactured selenium rectifiers were much more rugged and reliable
than the tube equivalents, but generally were more expensive. Since the power supply
is such a critical part of any electronic assembly, the tradeoff could be justified
if only for the boost in a product's reputation for having fewer breakdown issues.
While it is true that there are not many applications anymore for selenium rectifiers,
vintage materials and methods sometime experience a reincarnation in some other
form using modern formulations and manufacturing techniques. Having knowledge of
previous work can help spawn ideas for research and development toward solving new
problems...
 "As our lives become increasingly intertwined
with technology - whether supporting communication while working remotely or streaming
our favorite show - so too does our reliance on the data these devices create. Data
centers supporting these technology ecosystems produce a significant carbon footprint
- and consume 200 terawatt hours of energy each year, greater than the annual energy
consumption of Iran. To balance ecological concerns yet meet growing demand, advances
in microelectronic processors must be efficient and environmentally friendly. Northwestern
University materials scientists have developed new design principles that could
help spur development of future
quantum materials used to advance (IoT) devices and other resource-intensive
technologies while limiting ecological damage..."
 Through our flagship
SKY66430-11, Skyworks is powering new devices in the rapidly emerging
5G Massive Internet of Things (IoT) market. SKY66430-11 is the world's smallest,
fully pre-certified all-in-one system-in-package (SiP) incorporating cellular modem,
transceiver, RF front-end, memory and power management functionality, enabling LTE-M
and NB-IoT connected devices. This turnkey solution integrates Sequans' Monarch
SoC platform to support a wide range of low power, low data rate consumer and industrial
IoT applications including asset tracking, industrial monitoring, smart metering,
wearables and more. Receive low-pass filters are integrated into the SiP along with
the necessary matching to yield a 50 ohm single-ended impedance for the antenna.
The filters provide a high level of rejection to out-of-band interferers, protecting
the transceiver from high blocking signal levels...
 According to the Radio Museum website, B.F. Goodrich,
of Akron, Ohio, manufactured the
Mantola line of radio receivers. It was evidently a low quality,
low price, short-lived run of models. The simplicity of the schematic shows the
low parts count. A lack of multipole filter circuits likely means selectivity was
fairly marginal. One good feature is that unlike many earlier radios and TVs, the
AC line connection is DC-isolated through a 150 kΩ resistor (R13). Look at
the schematics of older sets and it is not uncommon to see one line of the AC supply
tied directly to the metal electronics chassis. An isolation transformer right
at the input is the safest way to do it.
 This assortment of custom-designed themes
by RF Cafe includes T-Shirts, Mouse Pads, Clocks, Tote Bags, Coffee Mugs and Steins,
Purses, Sweatshirts, and Baseball Caps. Choose from amazingly clever "We Are the World's
Matchmakers" Smith chart design or the "Engineer's Troubleshooting Flow Chart."
My "Matchmaker's" design has been ripped off by other people and used on their products,
so please be sure to purchase only official RF Cafe gear. My markup is only a paltry
50¢ per item - Cafe Press gets the rest of your purchase price. These would make
excellent gifts for husbands, wives, kids, significant others, and for handing out
at company events or as rewards for excellent service. It's a great way to help
support RF Cafe. Thanks...
 A few years back, I bought the issues of
The Saturday Evening Post which contained the very first published comics from Peanuts
creator Charles Schulz. As with just about everything else, they were available
on eBay for a few bucks apiece (although prices have really gone up since the beginning
of the year). Most of the issues also had articles and advertisements - and even
comics - that make appropriate fodder for both RF Cafe and my
hobby website, Airplanes and Rockets. Here are a few of the tech-related comics
I found. The first one might seem to be a bit distasteful to the survivors of the
RMS Titanic disaster and/or their relatives, given that only 36 years had passed.
The next one is about architectural engineer - ahem, and the Hazel comic applies
for obvious reasons...
 Windfreak Technologies designs, manufactures,
tests and sells high value USB powered and controlled radio frequency products such
as RF signal generators, RF synthesizers, RF power detectors, mixers, up / downconverters.
Since the conception of WFT, we have introduced products that have been purchased
by a wide range of customers, from hobbyists to education facilities to government
agencies. Worldwide customers include Europe, Australia, and Asia. Please contact
Windfreak today to learn how they might help you with your current project.
Tuesday 29
 This story from the 1976 issue of Old
Farmer's Almanac (OFA) is fair game for RF Cafe because of
its technical aspect, but there is yet another interesting reason that might require
an amateur radio operator to notice. "The Man Who Made Gasoline from Water" is about a 70-year-old inventor
named Louis Enricht who in 1916 tried to convince would-be investors that he had
discovered a method for converting a fuel tank filled with drinking water into gasoline
merely by dropping a magic pill into the filler tube. Henry Ford expressed interest
in the miracle pill, but a more skeptical businessman and chemist investigated the
matter. You'll have to read the story to learn the results (very interesting), but
you might be interested to know the name of that wise entrepreneur: Hudson Maxim.
Does that name sound familiar...
 "Graphene can be
sculptured by electron beams, according to researchers at Georgia
Tech. Carbon atoms can be added or subtracted - and in the case of graphene oxide,
surface oxygen can be used to remove carbon atoms with no additional chemicals.
'By timing and tuning the energy of the electron beam, we can activate interaction
of the beam with oxygen in the graphene oxide to do etching, or interaction with
hydrocarbons on the surface to create carbon deposition,' said mechanical engineer
Professor Andrei Fedorov. 'With atomic-scale control, we can produce complicated..."
 Antenova Ltd, UK manufacturer of antennas
and RF antenna modules for the Internet of Things (IoT) and Machine-to-Machine (M2M)
applications, has added a high performing 5G SMD design to its array of 5G antennas.
This brand-new antenna,
Lepida SR4L054, is a wideband antenna in SMD form, designed to
achieve high efficiency and performance right across the spectrum from 600 MHz
to 3800 MHz. Lepida operates right across the cellular bands B71 (617-698 MHz),
LTE 700, GSM850, GSM900, DCS1800, PCS1900, WCDMA2100, B40 (2300–2400 MHz), B7 (2500-2690 MHz),
and B78 (3300-3800 MHz). The antenna is linear polarised and has been designed
to ensure excellent coplanarity. Antenova has built Lepida for the more demanding
applications in 5G, 4G and LTE where antenna performance and reliability...
 Mystery stories were
broadcast on radio stations in the days before television - and
for quite a while after TV was available for that matter. Families gathered around
the living room radio set in excited anticipation of the next adventure of shows
like "The Shadow," "Amos 'n' Andy," "Tales of the Texas Rangers," "Dragnet," and
"The Green Hornet." During that era, it was common also for electronics magazines,
which focused largely on radio communications, to experiment with printed dramas
that had a radio-centric theme. Here is the first of a series tried by Radio-Craft
in the late 1930s. A couple decades later the Carl & Jerry adventures were run
in Popular Electronics, but other than that I don't recall seeing a lot of these
things. If you're a mystery fan, then here you are.
 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 (of course a gratuity will be graciously
accepted). 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 ...
 Triad RF Systems, a leading designer and
manufacturer of integrated radio systems and high performance RF/Microwave amplifiers,
just published a very nice Tech Brief entitled "Keys to Successful Naval Defense Using MIMO/MANET Radio System Deployments."
Beginning with a review of applicable radio history (HF, VHF, UHF, SATCOM), the
document extolls the virtues of MIMO (Multiple-Input / Multiple-Output) and its
antenna diversity scheme (a la your Wi-Fi router). Building on the technology is
MANET (Mobile Ad-Hoc Networking), which exhibits self-forming and self-healing networks
that survive in hostile signal environments. While the title specifies naval applications
because of Triad RF's extensive involvement in the realm, this technology extends
into other military services as well as domestic law enforcement...
 Reactel has become one of the industry leaders
in the design and manufacture of RF and microwave filters, diplexers, and sub-assemblies.
They offer the generally known tubular, LC, cavity, and waveguide designs, as well
as state of the art high performance suspended substrate models. Through a continuous
process of research and development, they have established a full line of filters
of filters of all types - lowpass, highpass, bandpass, bandstop, diplexer, and more.
Established in 1979. Please contact Reactel today to see how they might help your
project.
These archive pages are provided in order to make it easier for you to find items
that you remember seeing on the RF Cafe homepage. Of course probably the easiest
way to find anything on the website is to use the "Search
RF Cafe" box at the top of every page.
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