See Page 1 |
2 |
3 |
4 | of the March 2024 homepage archives. Thursday the 21st
 When I hear the name
Van de Graaff and think of the Jacob's Ladder gadget a lot of us built
in junior high school, it seems like the guy must have been born in the early to
middle 19th century, long before Nikola Tesla. In fact, Dr. Robert J.
Van de Graaff was born in 1901, and according to this death notice in
a 1967 issue of Radio-Electronics magazine, died in January of that year. Also in
the news was how aluminum was going to begin replacing copper for building wiring.
That didn't last long because by the early 1970s houses were burning down when the
soft aluminum cold-flowed at the electrical device screw connections, causing arcing
which then started fires. The National Electric Code prohibited its use in new construction
for sizes under 10 AWG sometime around 1975. That was when I first starting
out as an electrician in training. The industry went to copper clad aluminum for
a couple years, then back to solid copper shortly thereafter. Most insurance companies
today will not cover houses with aluminum wiring. Read on for other breaking news
of the day...
 The debate regarding the superiority of
coaxial cable and twin-lead cable, aside from personal preferences, comes down
to this: Twin-lead cable has lower loss but is vulnerable to extraneous signal pick-up
and is sensitive to nearby objects in the routing path from antenna to receiver;
it is also inexpensive. Coaxial cable has higher loss and is more expensive, but
is significantly less sensitive to the routing path and external signal interference.
In strong signal areas and/or for short runs, higher loss in coax is not an issue,
and its higher cost can usually be justified for the near immunity from interference
advantage. In areas where the signal at the antenna is weak and the path length
to the receiver is long, twin-lead, aside from its lower cost, helps yield a better
signal. The same pros and cons apply for the other direction with a signal going
from a transmitter to an antenna, but this 1965 Electronics World magazine article
is addressing television and radio reception...
 Withwave is a leading designer and developer
of a broad range of RF, microwave, and millimeter-wave test solutions and subsystems
with a focus on electromagnetic field analysis and signal processing. Our newly
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integrity solution for bench-top and automated test equipment to meet increasing
demands of the semiconductor and optical test industries, including 5G communications
and supercomputing. Vertical mount and edge mount configurations available with
2.54 mm and 4.00 mm connectors...
 Voltage multipliers were found in nearly
every form of battery-powered electronics in the days of vacuum tubes, because of
the 100-volt or more requirement for plate voltages. Primary batteries in 30, 45,
and 67½ volt sizes were produced by Eveready, Burgess, and a few other companies
in order to help simplify biasing circuits. They were bulky and heavy, often comprising
a significant portion of the assembly's volume. Heavy transformers contributed mightily
to the weight and size as well. Exell still manufactures 30, 45, and 67½ V
batteries both for the few products that are still designed to use them, and for
vintage radio owners. Most circuits that need higher DC voltages these days use
DC-DC converters, many of which are ICs that need only a small external inductor
(not a transformer). This 1953 article in QST magazine show how high voltages
were generated in the days of tubes...
 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...
Wednesday the 20th
 It's hard to say what over-the-air (OTA)
broadcast television audience size is these days, but there must be enough companies
making money from advertising adult diapers, electric scooters, insurance, hearing
aids, and supervitamins to pay for the service. I put up an old-fashioned Channel
Master long range, multielement VHF / UHF / FM antenna a decade ago while living
in Erie, Pennsylvania, in hopes of watching some local programming with news and
nearby company promotions. Boy, was I disappointed when most of what appeared was
useless programs packed with the aforementioned type of products and services. It
was pathetic. When this
Winegard Antenna Systems ad appeared in a 1967 issue of Radio-Electronics magazine,
it was a different world. Broadcast TV was the dominant entertainment medium, and
cable was just beginning to be installed in urban areas - basically where the signal
quality was already very good due to proximity to transmission towers. Convincing
people to pay for a service they were getting for free, and still having to sit
through commercials, was a good bit of marketing savvy. FYI, there are currently
12 VHF (2-13) and 56 UHF (14-69) channels reserved for OTA TV, for a total of 68...
 If you are a frequent visitor of RF Cafe,
you have probably seen an article or two on the history of television. Early color
TV systems used an electromechanical configuration that "chopped" the electron beam
into red, green, and blue sectors at a rate that combined on a projection screen
in a manner which presented a broad spectrum. One scheme that was a serious contender
over the all-electronic color system was the
CBS rotating disk. Believe it or not, the first color TV camera on the moon
was similar to the CBS system. An advertisement for a
Precision Optical Chopper
from Stanford Research Systems recently appeared in MWJ, that made me think
of the CBS color mechanism. There are
LCD type
optical choppers, but they are wavelength dependent and cannot switch at more
than a couple hundred Hz...
 Although the first patent for a
field effect transistors (FET) was assigned to Julius Edgar Lilienfeld in 1925,
it was not until sometime around 1960 that the first commercial product was available
- a MOSFET designed by Dawon Kahng and Martin M. (John) Atalla at Bell Labs. This
article from a 1972 issue of Popular Electronics magazine introduces the
hobbyist readers to properties and uses for the by-then common junction FET (JFET)
and MOSFET. Nowadays, MOSFETs are the backbone of the vast majority of integrated
circuits. Note in Fig. 3 where it is shown how the biasing and function of
a vacuum tube and n-type JFET are essentially the same. I often recommend to people
who are doing one of the Popular Electronics Quizzes that shows a vacuum
tube that they mentally substitute a FET for the tube, and proceed to arrive at
an answer...
 Is it my imagination, or does this tower
have a tilt to it? Since it's meant to demonstrate autonomous erection of communications
towers on the moon, I hereby dub it the Leaning Tower of Luna. "In a scenario
meant to mimic the lunar surface,
four robots cooperatively built a five-meter communications tower, including
antenna - and then disassembled it, simulating not only the construction of such
a structure but maintenance and sustainable operations for lunar infrastructure
development. Robotics company Gitai's Lunar Rover and three of its 'Inchworm' robots
achieved the build, which the company called 'groundbreaking' and a first of its
kind. Japanese operator KDDI was also a partner on the project, providing specifications
and information about their mobile phone base stations that allowed Gitai to develop
an antenna suited for robotic construction. Gitai's robotics were selected late
last year to be part of the Defense Advanced Research Projects Agency (DARPA)'s
10-Year Lunar Architecture capability study..."
 Maybe in 1951 when this "Corrugated-Waveguide
Band-Pass Filters" article appeared in Electronics magazine, placing
a special resonating form inside a section of waveguide was a reasonable option
for creating a bandpass filter response, but it sure seems like a hard way of accomplishing
the task. As shown in the photo and illustrations, a tapered metallic block with
machined fins spaced to resonate at a predetermined frequency created a high frequency
cutoff to work in conjunction with the natural low frequency cutoff frequency to
create a bandpass combination. A quick search did not turn up any references to
such structures being used in modern waveguide bandpass filters, although they might
exist. It appears iris coupling of resonating cavities is the method du jour. I
admit to not being a waveguide expert, so do your own research on this one. If nothing
else, this is a good historical reference...
 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 280k
per year (in eight locations on each page, with >17k pages)...
 Axiom Test Equipment allows you to
rent
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test equipment, repair
test equipment, or
sell or trade test equipment. They are committed to providing superior customer
service and high quality electronic test equipment. Axiom offers customers several
practical, efficient, and cost effective solutions for their projects' TE needs
and is committed to providing superior customer service and high quality electronic
test equipment. For anyone seeking a way to offload surplus or obsolete equipment,
they offer a trade-in program or they will buy the equipment from you. Some vintage
items are available fully calibrated. Please check out Axiom Test Equipment today
- and don't miss the blog articles!
Tuesday the 19th
 With less than 24 hours left in winter this
year (vernal equinox is March 19th at 11:06 pm EDT), I figured I had better
get this
snowflake
article posted now. It appeared in the 1986 edition of The Old Farmer's Almanac
(OFA). That's not a publication targeting old farmers, btw. For many decades, I
was a faithful purchaser and reader of the OFA, but sometime in the early 2000s,
the nature of its contents changed pretty significantly and I lost my interest.
I've got enough vintage issues with sunrise and sunset, moonrise and moonset, and
high and low tides tables that I don't need newer versions. Besides, all that up-to-the-minute
information is available online. But I digress... We've all been told about how
no two snowflakes are alike - like fingerprints - and that it has something to so
with static electric charges as the flake is formed. Even so, just like DNA controlling
how living cells divide and reproduce with and without symmetry, the creation of
a snowflake's unique symmetry is and variation is magical...
 This
is a very clever headline from the editors at Photonics magazine. You probably
know this, but in case not, a flock or collection of crows is referred to as a "murder
of crows." The
BirdSpot website offers an explanation for the strange and uncomplimentary moniker,
although the etymology is admittedly not for certain. BTW, we also refer to
a charm goldfinches, a siege of herons, a gaggle of geese, and a parliament of owls.
Begins the Photonics article: "Using a model laser scarecrow previously developed
at the University of Rhode Island, which looks less like a traditional scarecrow
and, in fact, much more like a traditional
laser module, the researchers presented flocks of European starlings with fresh
ears of sweet corn within an enclosure. The team performed two tests. In a 'stick
trial,' the researchers stuck corn on a wooden stake to simulate a stalk. In a subsequent
'natural trial,' they placed real corn stalks at various heights. Upon concluding
the trials, the team determined that the use of lasers as a scarecrow mechanism
reduced crop damage - marginally in stick trials and more substantially in natural
trials. The prospect for crop damage, they found, increased as the laser distance
increased..."
 There's not a much better way to wrap up
a work week than to read through a short technohumor (I just made up that word)
novel by
Carl Kohler or John T. Frye. Reading a few technocomics (another made-up
word) by various illustrators is a great resource, too. This story, which appeared
in a 1970 issue of Popular Electronics magazine, is another episode in
the life of technotinkerer (a "Maker" in today's lingo) Kohler (who also drew a
lot of the technocomics) and his skeptical helpmeet (for good reason) "Friend-Wife,"
as he unveils his repurposed homebuilt UNIversity computer...
 "MIT's breakthrough in integrating 2D materials
into devices paves the way for next-generation devices with unique optical and electronic
properties.
Two-dimensional materials, which are only a few atoms thick, can exhibit some
incredible properties, such as the ability to carry electric charge extremely efficiently,
which could boost the performance of next-generation electronic devices. But integrating
2D materials into devices and systems like computer chips is notoriously difficult.
These ultrathin structures can be damaged by conventional fabrication techniques,
which often rely on the use of chemicals, high temperatures, or destructive processes
like etching. A New Integration Technique To overcome this challenge, researchers
from MIT and elsewhere have developed a new technique to integrate 2D materials
into devices in a single step while keeping the surfaces..."
 Beginning in the 1960s, Popular Electronics
magazine had a long-running column titled "Solid
State" that reported on the newfangled science. Even in 1970, there were still
people who distrusted solid state electronic devices in terms of reliability and
ruggedness. Their skepticisms were not totally without merit at the time. However,
advances were occurring at a very rapid rate. This particular Solid State report
describes how charge coupled devices (CCD) might someday serve as photographic imagers
because of their efficiency at converting photon impingement to electric charge
in potential wells and the subsequent serial shifting of the data to an output port.
It also raves at the development by Motorola of RF power transistors (40 W)
that exhibited useful gain way up into the 25 MHz realm...
 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 280,000 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...
 ConductRF is continually innovating and
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library. They also provide custom coax solutions for applications where some standard
just won't do. A partnership with Newark assures fast, reliable access. Please visit
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how they can help your project!
Monday the 18th
 It's been a while since I posted a new set
of
electronics-themed comics from vintage magazines. These three appeared in a
1964 issue of Radio-Electronics. The page 37 comic shows the wife asking
a presumably inane question, but in fact there were duo-whatever vacuum tubes that
were the inclusion of a pair of single tube types, usually with a 12.6 V heater
voltage. A well-known example is the 12AX7, which is essentially a pair of 6AV6
triode tubes. Besides that, there was both a 6SN7 and a 12SN(X)7 tube, the former
with a 6.3 V heater and the latter with a 12.6 V heater. Here's a question
for you: What is that thing on the floor to the right of the box of vacuum tubes
in the page 37 comic?* The page 72 comic is not so far-fetched. I have no doubt
that somewhere in the world - multiple places and times, likely - people have heated
or cooked something in front of a microwave communications dish...
 A lot has been in the news recently about
Russia's new
hypersonic glide vehicle capable of delivering nuclear (and conventional) warheads
across the globe at over than Mach 20 (14,822 mph) in the atmosphere. That's
4.1 miles per second. From a 150 mile high apogee, that's less than 40 seconds from
space to target. Not even a high power laser can stop that. The
great circle path from Siberia to San Francisco is 5,900 miles, for a flight
time of less than a minute after launch phase. Moscow to D.C., (4,900 miles) takes
a little less
time. Here is a recent interview
with Putin on Russia's state of the union regarding social, economic, and military
issues - including hypersonic weapons. Oh, and they're not fixing their low birth
rate by importing felons, psycho patients and
cannibals from the third World. Interestingly, he addresses the rampant embezzlement
schemes that U.S. defense contractors and their management perpetrate. Sure, a lot
is propaganda, but so is what comes out of Washington.
 As with nearly things electronic, innovations
in
radar systems that were ground-breaking a few decades ago are now available
commercially at a small fraction of the cost, a much more compact size, and much
greater performance and reliability. Radar operators during World War II noticed
that they were able to detect strong rainstorms demonstrating that signals did not
necessarily need a metallic object to be reflected strongly enough to be received
and processed. Research began soon thereafter to build radars optimized for detecting
weather phenomena. Early weather radars were "simple" reflective types that indicated
distance, height, and speed (by comparing successive samples). Doppler radar was
developed next, adding a much greater capability to characterize particular weather
systems according to intensity, direction, rotation (hurricanes , tornadoes), composition
(ice, snow, rain, etc.), speed (average and gust), and other parameters...
 everything RF has published an eBook titled
"RF
Filter Digest 2024." This eBook is crafted to be a comprehensive resource for
anyone looking to learn about the current-generation RF Filters. With the introduction
of new wireless technologies, the frequency spectrum is getting very crowded. To
maintain seamless operation among these technologies without interference, RF Filters
play an integral role. RF Filters are crucial in optimizing signal transmission
and reception, selectively allowing desired frequencies to pass through while attenuating
unwanted signals. The "RF Filter Digest 2024" eBook discusses the challenges involved
with 5G mmWave filtering, high-rejection LTCC filter performance, the role of MMIC
filters in developing next-generation systems, and the impact of BAW filters on
5G applications. This eBook also includes an exciting section that discusses filter
design in the Cadence AWR design environment...
 Each month I used to post a list of articles
with advice on career enhancement including tips on preparing resumes, conducting
yourself properly at interviews, getting along well with co-workers, handling a
difficult boss, etc. I also posted links to polls and studies done on career
satisfaction, pay rates, education and experience levels, years in the field, etc.
Those types of articles have been around since Johannes Gutenberg invented the movable
type printing press. In the 1970s, Popular Electronics magazine ran a series
of articles titled "Opportunity
Awareness" that offered such advice, much of which in principle is still valid
today. One of the biggest advantages you can give yourself when job hunting is a
willingness to relocate to a new area - even if you need to pay for the move yourself.
I moved many times during my career and before getting my BSEE, paid my own moving
expenses as a technician...
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 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...
Friday the 15th
 There are many online
Fresnel Zone calculators. Most do the basic calculation for the maximum radius
of the Fresnel Zone
for a given frequency and separation between antennas. Some allow you to enter an
obstacle's distance from one of the antennas, and its height, then lets you know
if the obstacle falls within the Fresnel Zone. Very few plot the shape of the Fresnel
Zone, and even less include an obstacle positioned on the plot. Most rare are calculators
which take the curvature of the Earth into account. RF Cafe's
Espresso Engineering Workbook includes a Fresnel Zone calculator incorporating
all those features - and more...
 This "What's
Your EQ?" (EQ = Electronics Quotient) from a 1967 issue of Radio-Electronics
magazine offers just two challenges to your circuit analysis prowess. The first,
"Voltage Booster," is a classic black box (although I colored it blue) mystery where
you are supposed to figure out what is inside that produces the stated output given
a stated input. Spoiler: You'll need to be familiar with vacuum tube characteristics
in order to solve it. Unlike with many such circuits, a simple mental substitution
of a field effect transistor will not do the job. You might as well not even try
"Shifted Tuning" unless you have hands-on experience with tuning mechanisms of the
era. Just go straight to the answer, and gain an appreciation for advancements in
radio technology. Guys like Mac McGregor dealt with this kind of phenomenon on a
regular basis...
 LadyBug Technologies'
LB5975W is 50 GHz to 75 GHz a high accuracy, platform independent
RF & Microwave Power Sensor for general purpose average power or True RMS and
scalar measurements. The sensor features exceptionally fast measurement speed, a
broad dynamic range, and the widest set of options for programmatic and embedded
applications in the industry. LadyBug's feature rich Power Meter Application is
provided with each sensor. Time domain trace visibility is included and aids in
setting markers. The sensor is useful in research & development, manufacturing &
service applications including radar, satellite and telecommunications. Highlights
include coverage from 50 to 75 GHz, accurate power measurements on any modulated
signal, dynamic range: -50 to +18 dBm, Just Measure - patented NoZero NoCal before
use technology, and a variety of options such as triggering, security & analog
outputs...
 If you are a seasoned reader of episodes
of "Mac's
Service Shop," you might have noticed that the stories almost always begin with
either Mac or Barney commenting on the weather, which corresponds to the time of
year in which the story was originally published. Note the reference to the "bleak,
cold November morning" in this 1972 edition of Popular Electronics magazine. This
time around, the boss and trusty employee discuss the value of electronics kits,
Heathkits in particular. BTW, Heathkit is now making an impressive comeback into
the kit realm with new designs. Manuals for some of the more popular vintage Heathkit
projects are available again, which are a welcome thing to collectors. They also
are producing some replacement assemblies, like for replacing old Nixie tube displays
with LEDs (of course most people would probably rather have replacement Nixie tubes).
Back in the 1970s, before everything we bought was assembled in far away lands using
pseudo-slave labor, it was often less expensive to buy a kit of parts and put together
you own television or radio. It was also an era when electronics service shops still
did a brisk business fixing appliances, and building such devices were part of the
schooling process for up-and-coming technicians. Every study-at-home electronics
course included a color television, AM/FM stereo, and even build-it-yourself...
 "Researchers with Chinese telecommunications
giant Huawei spent three years developing the technology for its
foldable phone screens, drawing inspiration from the impact-absorbing qualities
of starches under certain conditions. Huawei's technical team told the Post that
the resilience of its Mate X3 and X5 phones stemmed from the unique properties of
a flexible inner screen beneath the scratch-resistant outer surface. The material
- which took more than 100 experiments to develop - is based on a phenomenon that
turns starch solution in the right proportions into a non-Newtonian fluid that acts
like water but hardens into a solid under sudden impact..."
 By the early 1970s, many types of vacuum
tubes had already been replaced by solid state devices. A lot of the resistance
by hardline lovers of glowing tubes was beginning to accept the reality of superior
electrical characteristics of many types of germanium and silicon diodes and transistors
over tube equivalents. During my enlistment in the USAF from 1978-1982, the vacuum
tube diode used to trigger the pulse forming network for the airport surveillance
radar (ASR) circuit was replaced with a plug-in solid state replacement. It seemed
to work just as well. I don't recall ever having to replace the faulty vacuum tube
version, so I cannot attest to whether the solid state version was an improvement.
Part of the motivation for replacing tubes with solid state devices was obsolescence
of the tubes, so maybe that is why it was done. The "fetrode"
introduced here by Solitron Devices in this 1973 issue of Popular Electronics
magazine was designed to be a plug-in replacement for the 6AK5 vacuum tube, which
is a pentode amplifier. Although not specifically stated, I assume the name "fetrode"
implies it was a field effect transistor (FET)...
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 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...
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.
About RF Cafe. I also
have an extensive list of
Recently Added topics.
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