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4 | of the December 2023 homepage archives. Wednesday the 14th
 Printed circuits were
originally printed on onto a substrate material - thus the name "printed." It
can be considered an early form of additive manufacturing, similar to printed
3-D objects nowadays. the opposite of additive manufacturing is, of course,
subtractive manufacturing. Modern
printed circuit boards (PCBs) have metal
removed during the etching process, hence, subtractive. When a metal ingot or
casting is machined and material is removed, that is subtractive manufacturing.
Prior to 3-D printers, had you ever heard of additive manufacturing. Me neither,
and for that matter, nobody ever spoke of subtractive manufacturing. But I
digress. The early printed circuits like the one featured here in this 1946
issue of Popular Mechanics magazine still used vacuum tubes. In this
case the full-size tubes were replaced by peanut tubes, but there were plenty of
PCBs that had standard tube sockets mounted to them. Eliminating the
time-consuming and error-prone point-to-point wiring in a cramped chassis was
worth the extra expense. It paved the way for more extensive use of printed
circuits so that the technology was maturing by the time semiconductors came
along a decade later...
 A few days ago I posted a webpage detailing
my work to generate equations for gain, phase, and group delay for a Butterworth
lowpass filter, using the basic polynomials. I could not find them anywhere on the
Web or in filter design books I own. The only difference between calculating Butterworth
lowpass, highpass, bandpass, and bandstop filter values for gain, phase, and group
delay is how the relative frequency is defined. Simply substitute the following
for ω in any of the equations for gain, phase, or group delay. It's that simple.
Graphs are published below. Frequency units cancel out, so a 1 Hz cutoff plots
the same as a 1 kHz cutoff or a 1 GHz cutoff for gain and phase. The group
delay scale needs to be divided by a factor equal to the frequency units (÷103 for
kHz, ÷106 for MHz, etc.)...
 According
to what I have found during Internet searches, this "The
G-Engines Are Coming" article is a much-sought-after story. It appeared in the
November 1956 issue of Young Men magazine (a 13-month-long title existing between
Air Trails and American Modeler). An article in the October 1958 issue of American
Modeler titled "Anti-Grav" referenced this story. Until Mr. Bob Balsie scanned the
pages from his rare copy of the original magazine, it was available nowhere. Science
fiction writers are fascinated with the concept of anti-gravitational devices. More
than one false premise forms the basis of this article, the most notable of which
is a claim of the existence of a "g-particle" (that which is responsible for the
gravitational force). Although the postulated possibilities for exploiting the misconception
are fantastic, we now know that only extragalactic beings possess such knowledge.
Do they walk among us?
 Robert Balin created many quizzes for
Popular Electronics magazine over his years with the magazine. This
Ganged Switching Quiz challenges your ability to trace out connections without
getting confused by crossovers - which is easy to do. Each of the six-position switches
illuminate a different combination of lamps. Your job, if you accept it, is to figure
out which lamps light for positions 1 through 6. Non-nodal crossing lines are not
typically shown broken as they are here, so don't misinterpret them as open circuits.
A huge list of electronics quizzes is posted near the bottom of the page...
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...
Tuesday the 13th
 This advertisement from Thordarson is from
one of my oldest editions of the American Radio Relay League's QST magazine
- December 1929.
Thordarson
Electric Manufacturing Company was founded in Chicago, Illinois, by Chester
H. Thordarson in 1895. He was the first producer of industrial and commercial transformers.
They are still in business today. Thordarson patented more than 30 inventions for
transformer design and manufacturing back in its early days, including the still
most popular form of laminations, the scrapless "E and I." Many discussions are
available on various transformer lamination configurations, including the very common
"E and I" types...
 "The head of the
Space Development Agency said delays to fiscal 2024 funding and the possibility
of an across-the-board budget cut would be 'a big deal' for his organization's acquisition
plans in the coming year. SDA Director Derek Tournear said Dec. 7, the agency has
already put some projects on hold due to the ongoing continuing resolution, which
pauses spending at fiscal 2023 levels. 'It's just too much uncertainty,' Tournear
said during a National Security Space Association webinar. 'The biggest thing that
we could ask for is predictability in the budget, passing a budget, so that we can
continue to move fast. Right now, we can move as fast as we can but uncertainty
in funding will put a break on everything. So, it's a big problem.' The agency was
established in 2019 to quickly field a constellation of hundreds of data transport
and advanced missile tracking satellites in low Earth orbit, about 1,200 miles above
the Earth's atmosphere. Those spacecraft will augment existing fleets of large satellites
and the plan is for SDA to upgrade its capabilities on a two-year cycle. The agency
began launching its first batch of satellites, dubbed Tranche 0, in April and September
and will finalize that tranche with a third mission early next year...
 This may be the only place you will ever
find the
explicit formulas for Butterworth lowpass filter gain, phase, and group delay
(until someone copies my work and doesn't give credit*). Hoping to avoid having
to do the messy math of complex numbers requiring separating out the real and imaginary
parts to obtain phase (θ) - and then to get the first derivative for group delay
(τd) - I searched high and low, far and wide for closed form equations. All I could
ever find was instruction to apply arg{H(ω)} for phase (θ) and -dθ/dω for group
delay -- pretty useless if you want to plug an equation into a spreadsheet or software.
Finally, I decided if I wanted the solutions, I would have to slog through all the
equations myself. Here is the result. The basic steps are as follow: Simplify the
polynomial factors by multiplying out the parenthetical quantities. Substitute jω
(or iω, but engineers use jω) for each "s," where ω is the frequency (ωn) being
evaluated divided by the cutoff frequency (ωco); hence, jω = jωn/ωco. Since j2
= -1 by definition, all even powers of j result in "real" parts and all odd powers
of j result in "imaginary" parts. E.g., for 3rd-order:H(s) = (s + 1)(s2
+ s + 1) =Re{H(jω)} = 1 - 2ω2 (parts w/o j), and Im{H(jω)}
= 2ω - ω3 (parts w/j). Gain is G(ω) = sqrt [Re{H(jω)2 + Im{H(jω)2]...
 Admittedly, I did not do any follow-up research
on this, but there is reason to believe that prior to this 1944 Radio News
magazine article, there was not a general agreement on what formula to use for
thermal noise in an electrical system. Here is a statement made by author S.J. Mallory,
"At first, however, there was no general agreement concerning the magnitude of this
basic Johnson noise power level. Some engineers used the quantity KTB, others used
2KTB and still others used 4KTB." We of course all use KTB nowadays for thermal
noise power - aka Johnson noise. It's a good read on the subject of sources that
determine the noise floor of a system. There's also this kind of Johnson noise...
 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...
Monday the 12th
 In 1965 when this "Buyer's
Guide to Shortwave Receivers" article appeared in Popular Mechanics
magazine, radio was a big deal. Transmitting required a license of some sort, but
anyone could buy a receiver and listen. It was decades before the Internet and cellphones
(which are radios) would make anytime, anywhere communications possible. News services
still reported breaking stories via "wire" or "wireless." Only big media organizations
and local newspaper offices had access to worldwide happenings. Many people used
shortwave radio broadcasts to listen in on news from across the state, country,
and world. Of course a lot of it was in a foreign language, but many countries also
broadcast in English. Three-letter government agencies also listened in to receive
reports from inside Communist countries where some oppressed citizens managed to
operate bootleg transmitters. Listening for coded messages from secret agents was
good sport; there were groups who traded information on them - much to the consternation
of the government. Believe it or not, there is still today a cadre of shortwave
listeners who maintain websites for assisting and trading info with the brethren...
 We really have it good today compared to
the early days of the
semiconductor revolution. Most of the most difficult problems were solved long
ago. Point contact devices were still fairly commonplace even in 1964 when this
ad appeared in Electronics magazine. Recall that the very first manufactured solid
state diodes and transistors were the point contact type that were encapsulated
in glass with a space gap where the contact was made. That left the device vulnerable
to vibration and impact damage and to contamination if the hermetic seal failed
between the metal lead and the junction(s). Unitrode claims to have been the first
to eliminate that issue with essentially a fully bonded package. Keep in mind, however,
that even the early semiconductor device packaging was no worse than the vacuum
tubes that they replaced, since the tubes also suffered from the same vulnerabilities
due to their construction. In fact, the process used with the early solid state
device packaging descended directly from vacuum tube construction...
 Conversion formulas between various forms
of 2-port network electrical parameters
is difficult to find, so once I finally located the paper that included them, I
felt it was my duty to publish it for public access. The paper is available on the
IEEE website by subscribers only. None that I found also include the correction
paper published a year later that addresses some of the technicalities of the S-
and T-parameter translations when complex impedance reference planes are used. In
order to avoid those sticky issues, I have reproduced only the sets of translations
that are unaffected. Many thanks to Mr. Frickey for his unique work. Recently, two
RF Cafe visitors wrote to comment on the conversions. You can read their contributions
here...
 Magazines
of yore were chock full of Christmas stories, holiday themes on the front cover,
and advertisements with both religious and secular messages as part of the sales
pitch. Take a look at the December editions of any of the vintage magazines hyperlinked
in the upper right part of the RF Cafe header area to see what I mean. The December
issues of QST typically featured a Christmas theme on the cover and Christmas
themes in many vendor ads. Same goes for my model airplane and amateur astronomy
magazines. This 1953 QST edition has a radio fax printout of a Christmas tree on
the cover - in full black and white :-). In 2019 when I originally posted this "YL
News and Views" column from the December 1953 issue of QST, there had been
a noticeable increase in Christmas decorations and even utterances of "Merry Christmas"
from checkout line clerks in the local stores. Inflation and interest rates were
low and attitudes were good...
 Axiom Test Equipment allows you to
rent or
buy 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!
Sunday the 11th
 This week's
crossword puzzle for December 11th sports an electronics theme. This being the
eleventh day of the month, many of the words begin and/or end with and/or contain
the letter "K" (denoted by an asterisk). 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 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, Hedy Lamarr, or
the Tunguska event in Siberia). The technically inclined cruciverbalists amongst
us will appreciate the effort. Enjoy!
 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...
Friday the 8th
 Long distance radio communications made
significant advances during World War II. It had to. With as widespread and
intense as fighting was, war rooms needed as much and as accurate information as
possible from land, sea, and air forces. Satellite systems were more than a decade
away when this news item on RCA Radiograms appeared in a 1947 issue of Popular
Science magazine. While improved transmitters, receivers, and antennas were
extremely important, perhaps the most significant factor in achieving reliable,
predictable long distance communications was a better understanding of the Earth's
upper atmosphere and how it affected the transmission of electromagnetic waves.
No direct measurements of ionospheric heights and conduction levels had been made
at the time, so it was a combination of theoretical and operational experience that
determined parameters necessary for success. After the war, when some strategic
secrets were divulged to the public, businesses and even private citizens were able
to enjoy the newfound benefits. Many of the companies that helped develop the wartime
technology were able to exploit that effort afterward...
 "It would be an overstatement to say that
the modern world runs on
rare-earth elements.
But as overstatements go, that one has more than a grain of truth. Because of their
unique luminescent, electrochemical, and magnetocrystalline properties, rare-earth
elements are essential to some of the most important and fastest-growing tech-based
industries. They're used in the phosphors that make white-light and other LEDs possible,
and they're in compounds used to purify key semiconductor materials such as silicon
carbide and gallium nitride, to indicate just a couple of their scores of applications
in technology. Perhaps most importantly, though, they're essential components of
the permanent magnets used in the motors of most electric vehicles and many appliances,
and also in the generators in most wind turbines. As much as 90 percent of processed
rare-earth elements come from China, a supply-chain dependence that spooks Western
executives and, especially, defense officials. That critical importance of rare-earths
in so many tech industries is of mounting concern in many Western countries. As
much as 90 percent of processed rare-earth elements come from China, a supply-chain
dependence that spooks Western executives and, especially, defense officials. Rare
earths are vital to countless military applications, including night-vision goggles,
laser-targeting..."
 As radio equipment builders and operators,
we still battle two fundamental issues that have been around since the beginning
of time (well, from Marconi's time, anyway) -
grounding and power supply fluxuations. Both topics are addressed briefly here
in this editorial column from a 1932 The Wireless World magazine. Back in the day,
grounding was referred to as "earthing," and was/is essential to optimal wireless
and wired performance. Line voltage "fluxuations" (fluctuations) are generally much
less severe today than in the 1930s thanks to better transformers, automated monitoring
and adjusting of line voltages, and better distribution designs. The worst type
of power line fluxuation - a lightning-induced surge - has been greatly reduced
thanks to superior engineering, primarily by the simple running of a grounded neutral
"static" wire running at the top of all the lines below it on utility poles and
transmission towers...
 Considering medical-diagnosis and other
safety-critical, sensory-processing applications that require accurate decisions
based on a small amount of noisy input data, the study notes that while Bayesian
neural networks excel at such tasks because they provide predictive uncertainty
assessment, their probabilistic nature requires increased use of energy and computation.
The increase is caused by the fact that implementing the networks in hardware requires
a random number generator to store the probability distributions, i.e. synaptic
weights. "Our paper presents, for the first time, a complete hardware implementation
of a Bayesian neural network utilizing the
intrinsic variability of memristors to store these probability distributions,"
said Elisa Vianello, CEA-Leti chief scientist. "We exploited the intrinsic variability
of memristors to store these probability distributions, instead of using random
number generators." A team comprising CEA-Leti, CEA-List and two CNRS laboratories...
 Hughes Aerospace has many openings for qualified
design engineers in Culver City, California. High power airborne transmitters, low
noise receivers using parametric amplifiers, solid state maser component development,
radar processing systems, crystal oscillators, telemetering, and high efficiency
spaceborne power supplies are among the kinds of specialties needed by Hughes to
support military and civilian projects. If you have been looking for just such an
opportunity, then the wait is finally over... provided you happened to see this
advertisement in Electronics magazine back in the fall of 1965. Quiz question:
What is the difference between a geosynchronous orbit and a geostationary orbit?
 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 280,000
per year (in eight locations on each page, with >17,000 pages). That's pretty
good exposure for $300 per month. Some companies have expressed an interest in being
able to manage their advertising accounts themselves a la the Google AdSense program...
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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