Today in Science History -
Triplex: Three Channels on One Channel" article that appeared in a 1956 issue
of Popular Electronics magazine was written by a fellow who was well known in the
aeromodeling world at the time - Claude McCullough. Claude won many titles in precision
scale for both control line (C/L) and radio control (R/C). As was the case with
many R/C modelers of the era, he did a lot of experimentation with transmitters,
receivers, and electromechanical devices used to move control surfaces. Rubber-band-powered
escapements dominated the field, but some servomechanisms were being developed to
provide a means for proportional control and/or a more powerful means of multiposition
control. As can be seen in the video I produced showing how a typical escapement
worked, the output drove the airplane's rudder to either neutral, full left, or
full right deflections, with no position in-between. To actuate the control, the
R/C pilot pushed a button on the transmitter the number of times required to affect
the desired control movement. That made for somewhat jerky flights, but it was a
very popular setup...
"When scientists discovered DNA and learned
how to control it, not only science but society was revolutionized. Today researchers
and the medical industry routinely create artificial DNA structures for many purposes,
including diagnosis and treatment of diseases. Now an international research team
reports to have created a
powerful supermolecule with the potential to further revolutionize science.
The work is published in Nature Communications. The researchers describe their supermolecule
as a marriage between DNA and peptides. DNA is one of the most important biomolecules,
and so are peptides; peptide structures are used, among other things, to create
artificial proteins and various nanostructures. 'If you combine these two, as we
have, you get a very powerful molecular tool..."
David Goins, founder of and chief engineer
for Windfreak Technologies, has written a number of application notes pertaining
to the specification and testing of RF and microwave frequency signal generators.
Most of the articles include features and applications for Windfreak Technologies
products, but the concepts are universally applicable. His latest, "Testing
RF Generators for Reliability" is featured here. It begins: "We pride ourselves
in designing, building, and selling high value radio frequency products that are
thoroughly evaluated and tested. All of our products go through rigorous testing
before releasing to our customers. Our devices have proven to be very reliable.
In rare cases, we have had a product come back for repair caused by output amplifier
failures. In this post, we explain the testing process we go through to ensure our
high-quality products and the two reasons for output amplifier failures..."
"What are these devices?" "How do they work?"
"What are their characteristics?" "How are they used?" Those are the kinds of questions
semiconductor diodes posed - and answered - in this article in a 1961 issue
of Popular Electronics. Author Jim Kyle runs through a short history of
he diode and then delves with more detail into physical construction, I-V curves,
power handling, junctions capacitance, resistance, etc. An interesting point mentioned
is that while a semiconductor diode will conduct some finite amount of current when
biased in the reverse direction (sometimes a desired characteristic), a vacuum tube
diode will not conduct at all when reverse biased - thereby making the tube a more
Westinghouse's motive for dubbing the
Model WR−8 the "Columnaire" is apparent when you see a photograph of it. This
model also had a −R version with remote control. The remote, though, has a cable
attached to it; it's not wireless like today's remote controls. There are some very
nice photos of a fully restored WR−8−R version on the AntiqueRadios.com website
forum. Look about half-way down the page. Near the bottom of the page is a copy
of an advertisement for the Westinghouse WR−8 with a price of $193 (~$3,563 in 2022
money per the BLS Inflation Calculator). The fundamental circuit of these receivers
is the WR−5 receiver chassis and power pack shown in Data Sheet No. 29. The model
WR−6 is a highboy; its circuit is the same as used in the WR-6, except as modified
for tone control. The Model WR−7 is similar to the model WR−6, except as modified
for an electric phonograph...
In response to my solicitation for information
on the origin of band letter designations,
a website visitor offered this: "I just looked at your web page that gives the names
of the various RF bands, and, in one place asked for any information on origins
of the names. I have some history on the band names that apply to UHF and above.
In the early days of radar (during WWII), the British and the U.S. researchers at
MIT chose, arbitrarily I believe, letter designations for radar frequencies. The
frequencies that were then possible to use for radio communication were just called
by their 'meter range' names: HF, VHF and UHF. The new frequencies that were then
only used for deployable radar sets, and for new technology looking for even shorter
wavelength radars, were given letter designations. So, in the 1940s and 1950s, radar
sets were identified as being UHF, L-Band, S-Band, C-Band, X-Band and K-Band. Later
they added Ku-Band - presumably for 'K Upper,' but I do not know..."
RF Cascade Workbook is the next phase in the evolution of
RF Cafe's long-running series, RF Cascade Workbook. Chances are you have
never used a spreadsheet quite like this (click here for screen capture). It is a full-featured RF system
cascade parameter and frequency planner that includes filters and mixers for a mere
$45. Built in MS Excel, using RF Cascade Workbook 2018 is a cinch
and the format is entirely customizable. It is significantly easier and faster than
using a multi-thousand dollar simulator when a high level system analysis is all
that is needed. An intro video takes you through the main features...
Alliance Test Equipment sells
used / refurbished
test equipment and offers short- and long-term rentals. They also offer repair,
maintenance and calibration. Prices discounted up to 80% off list price. Agilent/HP,
Tektronix, Anritsu, Fluke, R&S and other major brands. A global organization
with ability to source hard to find equipment through our network of suppliers.
Alliance Test will purchase your excess test equipment in large or small lots. Blog
posts offer advice on application and use of a wide range of test equipment. Please
visit Allied Test Equipment today to see how they can help your project.
This January 23rd custom made
crossword puzzle has an Amateur Radio theme, compliments of RF Cafe. All
RF Cafe crossword puzzles are custom made by me, Kirt Blattenberger, and have
only words and clues related to RF, microwave, and mm-wave engineering, optics,
mathematics, chemistry, physics, and other technical subjects. As always, this crossword
puzzle 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., Reginald Denny or the Tunguska event in Siberia). The technically
inclined cruciverbalists amongst us will appreciate the effort. Enjoy!
There are not many technical realms where
Google engineers have not either entered or created. Wireless connectivity is key
to their continued dominance in the information domain, so they understandably have
a vested interest in the "white space"
spectrum debate. White space comprises portions of the electromagnetic spectrum
where bands are either unlicensed or where licensed bands are or will be up for
grabs. An example of the former is the 2.4 GHz Wi-Fi band, and an example of
the latter is some parts of the broadcast television band that is being vacated
in areas. Although this information is a few years old, it shows how Google was
working early−on with the Federal Communications Commission (FCC) to build a real-time
database of what they term "dynamic spectrum" in order to provide useful information
about available white space (now directs here) to both users and providers. A separate
database is available for fixed and mobile spectrum. Enter your location of interest
and the map zooms into that region. For instance, in my town (at the time) of Erie,
Pennsylvania (see marker on map below), as of January 2013 when this was first posted
there were 21 channels available...
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
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.
Most(?) RF Cafe visitors are probably familiar
with British engineer John Logie Baird as being considered "the father of television."
His work in the 1920s produced both live and recorded motion pictures transmitted
and received electronically. What most visitors (including me) probably did not
know is that he also developed television apparatus using infrared imaging; he called
Noctovision (noct or nox meaning night) was a moving image form of the still imaging
"Noctovisor," which was an early night vision system that converted an infrared
image into an optical image. Radar was still in its infancy in 1942 when this article
appeared in Radio News magazine, and had not been implemented widely enough
to provided needed surveillance against nighttime bombing raids from Germany's Luftwaffe
(air force) flying across the English Channel. According to author Rosen, infrared
wavelengths have 16x the fog penetrating power of optical wavelengths...
Anatech Electronics (AEI) manufactures and
supplies RF and microwave filters for military and commercial communication
systems, providing standard LP, HP, BP, BS, notch, diplexer, and custom RF filters,
and RF products. Standard RF filter and cable assembly products are published in
our website database for ease of procurement. Custom RF filters designs are used
when a standard cannot be found, or the requirements dictate a custom approach for
your military and commercial communications needs. Sam Benzacar's monthly newsletters
address contemporary wireless subjects. Please visit Anatech today to see how they
can help your project succeed.
Together with Amazon's
Kuiper and the EU's
GalaxySpace and SpaceX's Starlink will
forever transform the night sky by launching tens of thousands of small LEO satellites,
each of which will reflect sunlight to observers situated between them and the sun.
Many - if not most - will be visible to the naked eye and will definitely appear
streaks in time exposure astronomical images. These systems will provide global
broadband connectivity at a projected cost of about $100 per month to those of us
who will actually shell out our wampum
for it, which is about the cost of equivalent cable-based Internet connectivity
now. As is the case now, our expensive subscriptions will continue to subsidize
the many who pay reduced rate or nothing for the service - another instance of a
few pulling the metaphoric welfare wagon while rest are in it for the free ride...
My first major high fidelity (Hi−Fi) stereo
system purchase came during my senior year at Southern Senior High School when I
had saved enough money to buy a combination AM/FM receiver, 8-track tape deck, turn
table, and two speakers with separate woofers, midranges, and tweeters. At the time
I thought the setup might impress friends and relatives... until I learned quite
quickly that "serious" stereo sound connoisseurs decidedly did NOT have equipment
with "Reader's Digest" logos on it. Oh well, the price seemed like a really good
bargain to me give the promised tonal superiority. Compared to the clock radio I
used previously for my music listening sessions, the Reader's Digest stereo system
produced music hall quality sound. Ah, the deep bass notes were grand. Spending
most of my earned money on model airplanes, rockets, and my '69 Camaro left little
disposable income for LPs (referred to as "discs" in this article), so the turntable
did not get much use. I did, however, read up on how to balance the tone arm...
"A TU/e research group has developed a new
near-infrared sensor that is easy to make, comparable in size to sensors in smartphones,
and ready for immediate use in industrial process monitoring and agriculture. This
breakthrough has just been published in Nature Communications, with co-first author
Kaylee Hakkel defending her Ph.D. thesis on January 14th. The human eye is a marvelous
sensor. Using three photoreceptor cells that
visible light into signals for different colors, the eye gives essential information
about the world around us. "When our brain puts the signals together, it makes a
prediction of what the signals mean based on our experiences. For example, a red
strawberry is sweet, but a green one is not..."
On Friday, January 28th and Monday, the 31st,
Rohde & Schwarz (R&S) will be conducting a webinar entitled "HF in a Nutshell."
You would be excused to thinking that this an amateur radio event because many of
the company's employees are Hams, but in fact it is billed as "An overview of current
beyond-line-of-sight communications solutions." Further, "HF communications technology
is reliable, proven and has been in service for decades. This webinar is the first
in a series covering HF topics and will illustrate that HF communications is in
no way your grandparents' technology, but rather THE communications solution for
the future. You will receive an overview of currently available Beyond Line of Sight
(BLOS) communications solutions and the latest developments in this field, i.e.
HF versus satellite communications (SATCOM)..."
Author Howard Wright takes the opportunity
here in a 1936 issue of QST magazine to distill the
of modulation down to its basic operation while dispensing with the garbled
mix of "graphs, formulas, charts, vectors, diagrams, and Greek letters which often
enter into various discussions of modulation." Mr. Wright describes how to
the uninitiated radio dial spinner, the culmination of events occurring behind the
scenes in an AM reception process is akin to this: "...it might be compared to the
reproduction of a color photograph in a magazine. How would we ever know that, to
be reproduced, the picture was broken down into its primary colors, if all we had
to go by was the original print and the magazine?" That is a very apt comparison...
The era of nuclear weapons of course began
in August of 1945 when they effectively ended World War II, but it wasn't until
around 1955 that another country - the U.S.S.R. - developed a deployable
thermonuclear bomb. Even before that happened, the U.S. Department of Defense
began planning for systems to detect and ultimately disable enemy ICBMs and aircraft-delivered
nuclear bombs. The nuclear arms race had begun, and continues to this day. Now,
there are five countries recognized as possessing thermonuclear weapons, three countries
declaring possession, and one country implying possession. A somewhat insane concept
dubbed MAD asserts that if everyone can strike and counterstrike with equal capability,
that will prevent nuclear warfare because the aggressor will suffer as significantly
as the victim. This 1961 Bell Telephone Labs promotion in Radio−Electronics
magazine introduced one of the early concepts for intercepting inbound ICBMs. The
most familiar and successful system...
Unlike the Roll Your Own Foil Capacitors
article in the same issue of Popular Electronics magazine, this one advising
how to reactivate leaky capacitors might be of use to a lot more people. The process
is called "reforming," and consists of applying a DC voltage to the faulty capacitor,
beginning at a very low voltage, and then slowly raising the voltage until the rated
working voltage (WVDC) is reached. Doing so, if the capacitor is not beyond rehabilitation,
will reconstitute the oxide layer that serves as the dielectric. This particular
item was presented as the answer to a question posed by a reader. A Google search
capacitor" will turn up more detail about the procedure. Most people recommend
against reforming unless you have no other option, as this writer from India might
have faced at the time...