|
 Both my father and grandfather were
stamp collectors - philatelists is the technical word - who dabbled
in a recreational way with commemoratives from foreign countries. Nearly all were
canceled (used) stamps that today, as back in their
day, have no real value other than to someone interested in history. Of course none
are the rare types. I now possess many of those stamps in an album that was painstakingly
hand-illustrated and assembled to arrange each stamp according to its country and
issue date. At one time I, too, dabbled in the hobby, having collected many plate
blocks and special issue U.S. stamps in the 1970s and 1980s, along with purchasing
a few designs of special purpose such as those with aerospace and communications
themes...
 Exodus Advanced Communications offers a
scalable portfolio of
high-power solid-state RF amplifiers designed for electronic warfare, GPS/GNSS denial,
and counter-drone applications. These systems are engineered to support high-power
RF denial architectures capable of disrupting control, navigation, and payload links
across multiple frequency bands. Integrated into mobile, fixed, and expeditionary
platforms, Exodus amplifiers enable reliable, long-range electronic attack performance
in complex and evolving threat environments. These solutions are deployed within
high-power RF denial systems across mobile and fixed counter-UAS platforms, as illustrated...
 "Measuring low-frequency electric fields
with high precision remains a significant challenge. Existing sensing technologies
often cannot deliver traceability, compact design, and the ability to detect field
direction all in one system.
Rydberg atoms are gaining attention in electric-field quantum metrology because
they have large electric dipole moments and their behavior can be tied to well-defined
atomic properties. Most current methods for detecting low-frequency or DC electric
fields using Rydberg atoms rely on vapor-cell electromagnetically induced transparency
(EIT) spectroscopy. However, this technique is limited..."
 Here are the
Majestic Chassis Models 380 A.C. T.R.F., and 400 A.C.-D.C. Superheterodyne
and
Delco 32-Volt Radio Receiver Chassis Radio Service Data Sheets
as featured in a 1933 edition of
Radio-Craft magazine. As mentioned many times in the past,
I post these online for the benefit of hobbyists looking for information to assist
in repairing or restoring vintage communication equipment. Even with the availability
of SAMS Photofacts, there are some models that cannot be found anywhere other than
in these vintage magazines...
 For the sake of avid cruciverbalists amongst
us, each week I create a new
crossword
puzzle that has a theme related to engineering, mathematics, chemistry, physics,
and other technical words. You will never be asked the name of a movie star unless
he/she was involved in a technical endeavor (e.g., Hedy Lamar). Clues in this week's
puzzle with an asterisk (*) are directly from this week's "High Tech News" column
on the RF Cafe homepage (see the Headline Archives page if necessary)...
 Please take a few moments to visit the
everythingRF website to see how they can assist you with your
project. everythingRF is a product discovery platform for RF and microwave products
and services. They currently have 354,801 products from more than 2478 companies
across 485 categories in their database and enable engineers to search for them
using their customized parametric search tool. Amplifiers, test equipment, power
couplers and dividers, coaxial connectors, waveguide, antennas, filters, mixers,
power supplies, and everything else. Please visit everythingRF today to see how
they can help you.
 In 1961, when these
tech-themed comics appeared in Electronics Illustrated magazine, the
"Space Race" was in full swing. That, along with home hi-fi stereo equipment, newfangled
color televisions, and - gasp - transistors, filled the headlines. They were also
the subject of many forms of humor. These four comics touch on many of those aspects,
all centered on the Space Race. Of course, everything is noticeably dated. "Flunking
the code test" means not much to Amateur radio licensees who earned their first
license (like me, in 2010) after the 5 WPM Morse code requirement was removed. Building
something in "kit form" was a good way to save some money and learn something...
 In our present "No user serviceable parts
inside" world of electronic products, it is easy to understand why very few people
have an appreciation for the technical prowess needed to troubleshoot and repair
them. When reading through these episodes of "Mac's Radio Service Shop" that appeared in mid last century editions
of Radio & Television News magazine, I am inspired to envy the skills
that small electronics repair shop owners had for working on the old vacuum tube
based radio and television sets. Digital electronics has its own unique set of quirks
and special knowledge requirements to troubleshoot, but when everything is analog
rather than merely being required to be a "0" or a "1"...
 "The U.S. Federal Communications Commission
(FCC) has announced that it is once again accepting applications for its
Honors Engineer Program. Initiated in 2018, the one-year development program
gives selected candidates an opportunity to work with FCC personnel on innovative
issues in the communications and high-tech arenas, including 5G communications technology,
the national deployment of broadband services, and communications technologies intended
to improve access to those with disabilities. Those selected to participate in the
Honors Engineer Program will be eligible for continued employment at the agency.
Application to the FCC's Honors Engineer Program is open to recent college graduates
with an engineering degree..."
 This week's crossword puzzle theme is
Amateur Radio. 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, amateur radio, 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...
 Submarines first proved their deadly capabilities
during World War II when Adolph Hitler's navy used them to torpedo not just
military ships but merchant ships in commercial trade routes between the Americas
and Europe. Hideki Tojo's navy used subs to conduct surveillance prior to the deadly
surprise attack on Pearl Harbor. Their naturally stealthy environment - underwater
- proved to be a difficult realm both for detection and for attack. Fortunately,
sensor technology developed quickly during the war, and soon a combination of air
and sea based methods were in use and proved very effective. Submariners no longer
sailed in relative security from being treated to a violent, icy burial at sea...
 The leading website for the PCB industry.
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.
 As
the Soviet army closed in on the Peenemünde rocket base in March 1945, German engineers
led by
Wernher von Braun initiated a desperate evacuation of their revolutionary research.
Tasked by von Braun, engineer Dieter Huzel organized the transport of tons of top-secret
blueprints and records to avoid capture by the advancing Red Army. Amidst the chaos
of collapsing lines and aerial warfare, Huzel successfully secured the documents
in an abandoned, ironclad mine near Goslar, shielding them from Soviet hands. After
dynamiting the entrance to seal the cache, Huzel and fellow scientists fled westward
to surrender to American forces. Following their successful arrival in U.S. lines,
the location was revealed...
 Sending telegraph messages, whether by wire
or wireless means, has always been expensive, particularly considering charges are
determined by the character (letter, number, symbol). Accordingly, the Shakespearean
line from Hamlet declaring that "brevity is the soul of wit" can be reworked to
"brevity is the soul of economy." A telegraph wire, unlike a telephone call, is
a legally binding communiqué, as is of course a written letter, but a telegram is
immediate transmission of information for time-critical messaging. A series of "commercial codes" were developed enabling senders to save often
significant money by sending multi-character codes that represented entire phrases
and/or sentences. What struck me about this article that appeared in a 1948 issue
of The Saturday Evening Post magazine...
 "With all the many pressures you have as
a product designer, does
electromagnetic
compliance (EMC) always seem like a stumbling block to delaying product sales?
Is your product exhibiting one of the top three failures: radiated emissions, electrostatic
discharge, or radiated immunity? Are you continually cycling between design/fixing
- running to the compliance test lab - failing again - and back to shot-gunning
more fixes? Wondering how to attack these issues earlier in the design cycle? Would
you like to learn how to characterize and troubleshoot simple design issues right
on your workbench? Then, this monthly column is for you..."
 In 1938, the designers at Sears, Roebuck &
Company's, Silvertone radio division were truly thinking "outside the box" when
they came up with this "Rocket" model
Models 6110. It is an ultra compact tabletop design with a unique
rounded top and a huge tuning dial that comprised one entire end of the Bakelite
cabinet, along with a set of six pushbuttons for station recall. Also published
were datasheets on the
Allied Radio Knight Model E10913, the
General Electric Model GD-52,, and the
Zenith Models 6D302, 6D311, 6D326, 6D336, 6D360. An ever-growing
list of models is at the bottom of every page...
 What drew my attention with this
P.R. Mallory & Company advertisement was not an actual
electronic component that they are most noted for - potentiometers, capacitors,
switches, metal alloys, and of course batteries (later renamed Duracell). Philip
Rogers Mallory began his company manufacturing tungsten wire for lamps. Rather what
interested me was the huge variety of standard potentiometer and rotary switch extension
shafts. Unlike modern electronics where pots and switches are typically mounted
to the enclosure with wires running to the circuit assembly, many...
 The failure to recognize
Nathan B. Stubblefield as the primary inventor of radio is a classic example
of how institutional power, financial interests, and the legal machinery of the
telecommunications industry tend to favor those with corporate backing over solitary,
unconventional inventors. Stubblefield's technology, which he demonstrated as early
as 1892, utilized induction and conduction through the earth and water rather than
the electromagnetic wave propagation (Hertzian waves) that ultimately became the
standard for modern radio. Because his method was effective only over relatively
short distances and functioned on different physical principles, it was eclipsed
by the work of Guglielmo Marconi. Marconi was the superior marketing force. He was
backed by a massive corporate infrastructure and was savvy in securing international
patents...
 Author T.A. Gadwa employs a
standing wave mechanism analogy that I don't recall having read
before - that of a dam on a river. The river is the transmission line with a lake
as the source and then he imagines a dam load. The dam standing waves, per his description,
have phase and amplitude characteristics that depend on how tall the dam wall is
relative to the surface height of the dammed river. An extensive array of graphs
is provided showing how the current of the dam standing waves react to the dam transmission
line termination impedance...
 Here are a couple more
electronics-themed comics, this time ones that appeared in the October 1951
edition of Radio & Television News magazine. When is the last time
you saw a comic in a technical magazine? Note the AC power cord attached to the
"portable" television. Television was a big deal in the day (I assume the "His"
on the guy's towel implies that "Hers" is at the other end of the power cord). Color
TV was not commercially available until a few years later. Nowadays, a person would
have a smartphone, tablet, or notebook computer while on the can. There is a huge
list of other comics at the bottom of the page...
 "Once upon a time in Europe, television
remote controls had a magic
teletext
button. Years before the internet stole into homes, pressing that button brought
up teletext digital information services with hundreds of constantly updated pages.
Living in Ireland in the 1980s and '90s, my family accessed the national teletext
service - Aertel - multiple times a day for weather and news bulletins, as well
as things like TV program guides and updates on airport flight arrivals. It was
an elegant system: fast, low bandwidth, unaffected by user load, and delivering
readable text even on analog television screens. So when I recently saw it was the
40th anniversary of Aertel's test transmissions, it reactivated a thought that had
been rolling around in my head for years..."
 I have a confession to make regarding the
puzzle titles. While all
RF Cafe crosswords do in fact use only my hand-entered dictionary
of terms and clues (literally thousands accumulated over the years) that pertain
exclusively to science, engineering, chemistry, physics, mathematics, astronomy,
etc., the choice for a particular title is to help attract search engines to the
page. There is nothing deceptive going on, just an attempt to exploit the nature
of search engine algorithms that rank pages based on meta tags coinciding with relevant...
 Sam Benzacar, of Anatech Electronics, an
RF and microwave filter company, has published his
April 2026 Newsletter that, along with timely news items, features his short
op-ed titled "Bell Labs in Murray Hill Celebrates." Sam, whose company is located
not far from Murray Hill, extolls the many discoveries and inventions that took
place there since its founding in 1925 as Bell Telephone Laboratories. It was originally
a subsidiary of AT&T and Western Electric, later becoming part of Lucent Technologies
and Alcatel-Lucent before Nokia's acquisition in 2016. Sam reports on the facilities'
recent 100th anniversary celebration. The list of accomplishments would will volumes...
 The transformative role of ferrites - crystalline
structures composed of iron oxide and metallic additives - in advancing modern electronics,
is reported in this 1961 Electronics Illustrated magazine article. Ferrites
uniquely combine magnetic properties with electrical insulation, enabling high efficiency
at frequencies where standard iron cores fail due to eddy current losses. This "electronic
wonder material" proved critical for television development, allowing for larger
picture tubes through efficient flyback transformers and deflection yokes. Furthermore,
ferrites revolutionized computing by providing reliable, compact memory cells, replacing
failure-prone vacuum tubes in machines like the Whirlwind I. Beyond these core
applications, the material facilitates innovations such as ultrasonic ...
 "In 1627, a year after the death of the
philosopher and statesman Francis Bacon, a short, evocative tale of his was published.
The New Atlantis describes how a ship blown off course arrives at an unknown island
called Bensalem. At its heart stands Salomon's House, an institution devoted to
'the knowledge
of causes, and secret motions of things' and to 'the effecting of all things
possible.' The novel captured Bacon's vision of a science built on skepticism and
empiricism and his belief that understanding and creating were one and the same
pursuit. No mere scholar's study filled with curiosities, Salomon's House had deep-sunk
caves for refrigeration, towering structures for astronomy, sound-houses for acoustics,
engine-houses..."
 Werbel's new
WM2PD-1.5-20.5-S-ECO, 2-way power divider covers 1.5 to 20.5 GHz and is
designed for engineers who need wideband performance in a compact, cost-efficient
package. Optimized for size, bandwidth, and manufacturability, it is well suited
for high-volume applications, lab use, and general-purpose signal distribution where
extreme port match is not required. Designed, assembled, and tested in the USA.
"No Worries with Werbel!"
 The radar system I worked on in the USAF
used two early memory types described in this 1956 Popular Electronics
magazine article. In fact, the radar was designed during that era, so it is no surprise.
Our IFF secondary radar had a whopping 1 kilobyte of
magnetic core memory in its processor circuitry. It consisted of 1024 tiny toroids
mounted in a square matrix with four hair-width enamel coated wires running through
them as x and y magnetization current lines, sense, and inhibit functions. If my
memory serves me (pun intended) after three decades away from it, the TTL circuitry
(no microprocessor) stored range values to calculate speed and direction from sample
to sample. The other memory type was a mercury acoustic delay line contraption having
a piezoelectric transducer at one end to launch an electrical pulse along its length
and another transducer at the other end to convert back to an electrical pulse...
|
 • European
Electronics Distribution Gains Momentum
• UK
Secure Quantum Communications Boost
• 2026
PC Sales down 11.3%, Tablets down 7.9%
• Starlink
Becoming Mainstream Option
• U.S.
Engineering
Ph.D. Programs Losing Students?
 The
RF Cafe Homepage Archive
is a comprehensive collection of every item appearing daily on this website since
2008 - and many from earlier years. Many thousands of pages of unique content have
been added since then.
 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 225,000 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...
 Here is another example of how enthusiastically
both manufacturers and consumers were met news of the impending end of World War II.
Amateur radio operators were amongst those most affected
during the war years because of the FCC having issued a moratorium against
transmissions, for security purposes. The same thing happened during World
War I, in fact*. Back in the day when citizens were fiercely patriotic and
appreciative of their freedoms, many Hams of service age answered a call to
donate certain kinds of equipment (panel meters, tuning capacitors,
transformers, etc.) for use in repair and retrofitting of field gear. They also
enlisted by the tens of thousands to lend their radio skills in the service of
their country. To the government's credit, the sacrifices were repaid
handsomely...
 Windfreak Technologies is proud to announces
the availability of our
FT108, an innovative
programmable bidirectional filter bank spanning a frequency range of 5 MHz
to 8 GHz in 15 bands. Band selection can be controlled through USB, UART or
at high speeds through powerful triggering modes. Each unit is factory tested via
network analyzer with unique data stored in the device to help with its use. Crossover
frequencies are stored so the user can send a frequency command and the FT108 will
utilizes Intelligent Band Selection logic to automatically toggle the optimal
filter path based on minimum insertion loss. Readback of FT108 insertion loss at
any frequency between crossover points allows for easy amplitude leveling...
 This custom
Wireless Engineering themed Crossword Puzzle for September 11th, 2022, is brought
to you by 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 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!
 Most people know that World War II marked
the point at which a large percentage of American women made a major move from the
role of homemaker to the roles of factory and trades workers. The societal shift
was made necessary because a large percentage of American men were off fighting
the war in Europe and the South Pacific, and therefore were not available to do
those tasks. This article appeared in the September 1942 edition of Radio Retailing
Today magazine less than a year into America's involvement in the War. Even
a militant feminist would probably conclude that, given the state of the world at
the time, it is a very fair assessment and generally exceedingly complimentary.
Note this observation regarding use of women for manufacturing, "Women have made more radio tubes and radio sets than men ever will."
I thought about that while preparing for the restoration of my 1941 Crosley Model
03CB console radio...
 Life for the blind has always been fraught
with obstacles that we who can see will never be able to fully appreciate. Society
has come a long way in accommodating the special needs of those with no or severely
reduced eyesight. Recent news stories report of experiments with electronic implants
that use implants set into the eye and couple somehow with the retina to send image
information to the person's brain. While in no way close to being able to be called
sight, it has at least allowed the guy or girl with training to detect and avoid
obstacles based on changes in scenery shading. We are probably a century away from
true bionic vision. Incremental improvements will thankfully improve the lives of
our thusly challenged brethren. This article from a 1947 edition of Radio News
magazine reports on efforts made by the
New York Institute for the Educations of the Blind to make amateur radio accessible
to interested students. It is no small accomplishment to learn the material and
apply electronics and communications principles with your eyesight, so I have a
great admiration for those who master the science with a handicap. Can you imagine
learning to solder by "touch?" The American Amateur Radio League (ARRL) has a collection
of resources for sight impaired enthusiasts...
 If you think government bureaucracies meddling
in the affairs of private business is a relatively new phenomenon, think again.
Elected and unelected persons and agencies have since the inception of control over
the populace made it their business to dictate which pursuits of technology are
sanctioned and which are not. Often, the motivation lies in who within those bureaucracies
stands to benefit monetarily from the decision. In this story lamenting the painfully
and, in the author's opinion, unnecessarily long time experienced in bringing commercial
broadcast television to the marketplace - in 1935. One of the primary stumbling
blocks was the Federal Communications Commission (FCC) preventing companies from
televising paid commercials during programs because, in the FCC's view, picture
quality was not good enough to serve advertisers' interests. In the process...
 I have never seen study-at-home audio-visual
(AV) physics courses offered by Albert Einstein or AV courses on chemistry promoted
by Ernest Rutherford, but I can now say I have seen study-at-home AV courses offered
by electronics pioneer Lee de Forest. This full-page advertisement for the de Forest's
Training, Inc., company of Chicago, Illinois, appeared in a 1945 edition of
Radio-Craft magazine. The vaunted (at least by the company)
"Syncro-Graphic" training was an early attempt at the paperless classroom. The
student watched films reels of instruction rather than "frequent flipping of pages
to refer back or ahead to illustrations mentioned in text." It would be another
50 years before useful computer-based-training (CBT) courses became available for
home use, but you have to give the "Father of Radio" credit for being ahead of his
time in instruction techniques...
 Being the old guy I am, seeing the tag line
"No
Sweater Girls, Please" in this 1944 National Union Radio and Tubes company advertisement
in Radio News magazine reminded me of a comedian's bit about Sweater Girls.
The reference could be interpreted as a slight to women of certain physical attributes,
but in this case it was a play on a popular theme in Hollywood. The actual message
pertained to how contaminant-free National Union kept its vacuum tube assembly areas.
Radio News, being by default a men's magazine since in the day most electronics
professional and hobbyists were male, and seeing what would today be considered
sexist or misogynistic was not uncommon. Take a look at some of the comics that
appeared to see what I mean. Most of the jokes were on men though; that kind of
humor was also OK back then. Now jokes about men (dare I also specify White men?)
are the only socially acceptable...
 This quiz is based on the information presented
in Introduction to Antenna Analysis Using
EM Simulation, by Hiroaki Kogure, Yoshie Kogure, and James C. Rautio, published
by Artech House. It is written for novice engineers and engineering students. This
easy-to-comprehend resource offers readers thorough introductory-level treatment
of antenna analysis using electromagnetic (EM) simulators. This richly-illustrated
book shows how to use EM software to analyze and tune wireless antennas to meet
specific requirements. Readers learn important wireless antenna design terminology
and gain a detailed understanding of how antennas work. Moreover, the book offers
guidance in troubleshooting problems with wireless antenna designs...
 It had been only a little over a decade since
the transistor was invented when this article appeared in the August 1959 edition
of Popular Electronics. Transistors were still a mystery to most people,
including engineers, technicians, and hobbyists. Author James Butterfield takes
a unique approach in presenting the material by writing it as a dialog between an
instructor and a student. If you are also
new to transistors, this will be worth your while to read. The
basics will never change. As an aside (and mentioned in the article), while still
a technician I had a manager one time who actually told an engineer working for
him that a transistor could be made by soldering two diodes together and using the
center node as the base connection...
 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 225,000k per
year (in eight locations on each page, with >17k pages)...
 The eleventh hour of the eleventh day of
the eleventh month - November 11th, at 11:00 am - that is when the armistice (cease
fire) began in 1918, unofficially ending World War I. This music video
Veteran's Day tribute is by Canadian citizen
Terry Kelly. It was written after an experience he had on Veterans Day in 1999.
Terry went blind at an early age, but has excelled as an athlete and a musician.
"A Pittance of Time" is done in the finest Celtic tradition. Per the U.S. Department
of Veteran Affairs website: "World War I – known at the time as 'The Great War'
- officially ended when the Treaty of Versailles was signed on June 28, 1919, in
the Palace of Versailles outside the town of Versailles, France. However, fighting
ceased seven months earlier when an armistice, or temporary cessation of hostilities,
between the Allied nations and Germany went into effect on the eleventh hour of
the eleventh day of the eleventh month. For that reason, November 11, 1918, is generally
regarded as the end of 'the war to end all wars...'"
 This week's crossword puzzle will keep you
busy for a while. Since 2000, I have been creating
custom engineering- and science-themed crossword puzzles for the brain-exercising
benefit and pleasure of RF Cafe visitors who are fellow cruciverbalists. The jury
is out on whether or not this type of mental challenge helps keep your gray matter
from atrophying in old age, but it certainly helps maintain your vocabulary and
cognitive skills at all ages. A database of thousands of words has been built up
over the years and contains only clues and terms associated with engineering, science,
physical, astronomy, mathematics, chemistry, etc. You will never find a word taxing
your knowledge of a numbnut soap opera star or the name of some obscure...
 British engineer John Sargrove was to the
production of radios what Henry Ford was to automobiles. At the time this "Robot
Makes Radios" article appeared in a 1947 issue of Radio-Craft magazine, Sargrove
had recently put his
Electronic Circuit Making Equipment (ECME) fully automated assembly line into
operation. Applying knowledge from two decades of developing methods of crating
inductors, capacitors, resistors, and interconnecting conductors using controlled
deposition of various materials on flat substrates, he was able to build 2-tube
AC/DC radios at a rate of up to three per minute, with only two ECME operators -
one at the input and one at the output. The only manual assembly required was the
installation of a potentiometer-switch, a transformer, speaker...
 James Kilton Clapp in 1948 first published
details on an oscillator that used positive feedback obtained from an LC (capacitive &
inductive) voltage divider to initiate and sustain oscillations. Thus was born the
now familiar Clapp oscillator. It had an advantage over both the Colpitts and Hartley
oscillators because the feedback, not being dependent on a simple capacitive or
inductive voltage division, respectively, made it more reliable as a variable frequency
oscillator (VFO). This article does a nice job of explaining the operation of the
Clapp oscillator. Just as the Colpitts and Hartley oscillators handily provide an
easy mnemonic for being based on voltage dividers of capacitance with the Colpitts
oscillator and inductance (Henries) with the Hartley oscillator, the Clapp oscillator...
 According to this 1972 article in Popular
Electronics, there were as many as 50,000 computers in the world at the time using
magnetic core memories. Among them was the Apollo Guidance Computer that was onboard
the Apollo 11 Lunar Module that Neil Armstrong used in July 1969 to land on the
moon*. Semiconductor memories were being manufactured in 1972, but believe it or not
they were not as fast as the magnetic core memories. Machinery was not available with
enough precision and repeatability to thread the read, write, sense, and inhibit wires...
 Cruciverbalists rejoice! Here is another
tech-related crossword puzzle to try your technical prowess. Unlike the weekly
RF Cafe crossword puzzle that contains only engineering, science, mathematics and
other tech words, this one from Electronics World does have a few unrelated
words. The big difference between making crosswords then and now is Mrs. Le Fevre
had to construct the grid of words manually, whereas I just create a huge file of
words and definitions, draw the grid outline, and then click a button to have software
put it all together. I'm guessing it took a couple hours to make this puzzle...
 Homepage
Archives for January 2023. Items on the RF Cafe homepage come and go at a pretty
fast rate. In order to facilitate fast page loading, I keep the size reasonable - under a megabyte (ebay, Amazon, NY Times, etc., are multiple
megabytes). New items are added at the top of the content area, and within a few
days they shift off the bottom. If you recall seeing something on the homepage
but now it is gone, fret not because many years I have maintained
Homepage Archives. |
