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 Those of you who are not particularly interested
in
vintage electronic equipment will please indulge those of us who
are. I post these articles occasionally to remind people of from whence we have
come. Whether you are an amateur radio operator or just a cellphone user, appreciation
is due to the pioneers who took the metaphorical arrows for us so that we may enjoy
the micro-size, low cost, high quality communications available today. The full-height
equipment racks in the photos were standard fare in the 1930s for long distance
(DX) shortwave operators - often only for CW (Morse code). "User serviceable parts
inside' was the rule rather than the exception. As much as I like waxing...
 Anritsu announced the launch of its new
Tensor Vector Network Analyzer (VNA) at IMS 2026. The Tensor VNA represents
a major advancement in RF and microwave network analysis, delivering modern, scalable
architecture designed to support the most complete and demanding measurements like
amplifiers, filters, frequency convertors, and other advanced VNA measurements.
Tensor VNA sets a new benchmark in vector network analysis with its revolutionary
source-per-port architecture, integrated AI intelligence, and exceptional power
handling. Engineered to meet the evolving requirements for aerospace and defense,
semiconductor, active and passive device measurements, signal integrity, research
and development, and millimeter wave / waveguide...
 Here
is a reprint of an article I had published in Wireless Design & Development
magazine in 1995. Some of the references are a bit dated, but the info is all still
very useful. Waypoint Software is now RF Cafe, and TxRx Designer is now Shareware
by the name of RF Workbench. With the advent of high speed personal computers, a
very insightful graphical method of determining inband mixer spurious products has
been largely forgotten. The
Spur Web™
(my name trademark, but used widely w/o attribution) chart rapidly identifies both
inband and out-of-band spurs, affording a pictorial view of where conversion system
frequencies lie with respect to all spur products. A comparison...
 The neighborhood where I grew up in the
1960s and 1970s was about 25 to 30 miles from the "big three" network television
broadcast stations (ABC, CBS, NBC) in Baltimore and Washington, D.C. That is considered
a fairly long distance in the over-the-air TV realm. Knowing what I know now, I
am somewhat surprised that those in our area were able to receive programs as well
as we did when all the homes I recall had just a single, standard multi-element
antenna on the roof. If anyone had stacked, phased array setups like this
Finco Co-Lateral TV Antenna installed, I certainly do not remember
any. Most of the antennas in Holly Hill Harbor and the surrounding communities did
not even have an antenna rotator, yet evidently were pulling in signals satisfactorily
- and without needing to be mounted on a tall...
 In this Radio & Television News
magazine article, author Jack Gallagher derives a formula for the number of turns
of wire to wind on a form of given dimensions for a parallel
constant-resistance network. He argues that although commonly
used formulas like that of Wheeler provide the number of turns needed to achieve
a desired value of inductance, it does not predict the size of cross-sectional shape
of a coil form that results in an optimal configuration. His work applies to audio
frequency divider networks like those used for speakers to steer specific frequency
ranges to a woofer, midrange, and tweeter trio; hence the need for "constant resistance"
(e.g., for standard 8 Ω or 16 Ω speakers)...
 Satellite direct-to-device (D2D) networks
represent the next frontier in mobile connectivity, promising to eliminate dead
zones by linking ordinary cellphones directly to orbiting satellites. Companies
like SpaceX with its Starlink system, AST SpaceMobile, and others are racing to
deploy constellations that can serve standard smartphones without specialized hardware.
The technology relies on large phased-array antennas in space, advanced beamforming,
and new spectrum-sharing arrangements with terrestrial carriers. Proponents argue
D2D will bring emergency communications and basic connectivity to remote areas worldwide.
Critics raise serious concerns...
 During my electronics technician days at
the Westinghouse Electric Company's Oceanic Division in Annapolis,
Maryland, I spent the first couple years building printed circuit boards, wiring
harnesses, and system-level assemblies for U.S. Navy sonar systems. We had some
really slick stuff like towed vehicles with transducer arrays along the sides, nose
cones for smart torpedoes, flow sensors, proximity fuse elements, etc. Exposure
to all that, and the super-smart people that designed it, fuelled my desire to go
to the trouble of earning an engineering degree. One of my tasks for a while was
to build the transducer arrays, which entailed building the hundreds of tiny transducer
elements. One of the phased...
 With the extreme volatility of today's
stock market, I thought this might be a good time to re-post an article I wrote
back in 2012 entitled "Arbitrage
via Microwaves." The ±200 point daily swings of a mere 8 years ago seem
paltry compared to ±1,000 of late. The original page on the IEEE Spectrum
magazine website is dead now, so I had to change the hyperlink to an archived page
on The Wayback Machine - a
great resource for you to remember if you ever need to retrieve a webpage that has
been disappeared [sic]. My piece begins: "If you have wondered why the world's
stock markets behave the way they do, why the DJIA falls 150 points on one day on
news of Greece leaving the euro...
 You wouldn't know it from the lineup
of
Crosley Corporation radios and turntables appearing in department
stores, but the company also manufactures dishwashers, ranges and freezers, clothes
washers and dryers, and air conditioners. That is still a small chunk of what Crosley,
based in Cincinnati, Ohio, made back in the middle of the last century, including
cars and trucks, a small private airplane (the Moonbeam), television sets and even
had a television broadcast station, as well as other items that were part of the
mainstream of American life. Take a look at their About Crosley webpage for more
insight. Amazingly, along with the extensive line of retro radios and turntables,
they still also...
 What got my attention in this 1955 Radio &
Television News magazine article was the "picture-on-the-wall" concept being predicted by General Electric
(G-E) engineers, based on its light-amplifying phosphor invention. Determining exactly
how the device works is difficult based on the information given, but it appears
that the ultraviolet light source which is being amplified is projected onto the
surface of the amplifying substrate, and then an exact duplicate of the image is
reemitted toward the viewer. The conceptual drawing of a large screen hanging on
the wall is most likely driven by a UV projector located near the ceiling, akin
to how the large screen home theaters popular in the early...
 When most people are asked to name
prolific inventors, people like Thomas Edison and George Westinghouse,
with 1084 and 361 each, respectively, come to mind - at least for the United States.
As of this writing, Kangguo Cheng of IBM holds the record with 2039 U.S. patents
assigned. Nikola Tesla had about 300 patents. Lee de Forest, the subject of
this 1937 Radio-Craft article, had a little over 180 patents. That still
qualifies as prolific by my estimation. However, there is more to ranking a person's
inventive worth than the number of patents awarded - like how profoundly his or
her invention(s) impacted the world. For instance, Alexander Graham Bell had a mere
18 patents...
 Development of the
cavity magnetron during World War II helped change the destiny
of Allied forces through using high frequency radar with enough power to detect
distant targets while using frequencies which were out of the normal detection bands
of Axis forces' receivers. Most equipment at the time could not operate efficiently
(or at all) above a few hundred MHz. It was considered a top-level secret with great
concern that the technology not fall into the hands of German and Japanese scientists.
According to this early post-war advertisement in a 1945 issue of Radio News,
Bell Labs was totally consumed by the development of magnetrons, and was relieved
to finally be able to boast of its...
 Exodus Advanced Communications presents
the
AMP20162, a high-power, solid-state amplifier designed for low frequency applications,
including radiated susceptibility (RS103), EMI/RFI lab and general broadband testing.
Covering 10 kHz to 250 MHz, this wideband system ensures signal integrity
and flat response, making it a reliable choice for demanding environments. The AMP20162
provides between 2500 and 3000 W, typical, across the frequency range and boasts
a P1dB of 1700 W. Utilizing a Class A/AB design, the AMP20162 supports all
modulation types and 64 dB gain while maintaining harmonic performance around...
 While
FM broadcasting (frequency modulation) began in the United States
in the late 1930s, it was not until after World War II and even the Korean
War, in the 1950s, that the major shift to FM took place. It took even longer for
FM to get a foothold in Europe mainly due to the emphasis on rebuilding essential
infrastructure and manufacturing destroyed by the war. As this article points out,
the newer FM radio features allowed it to thwart some of the propaganda efforts
of the Soviets in East Germany who would be stuck in technologies that lag two or
more decades behind the free world even to this day (ain't Communism / Socialism
great?). The "medium-wave band" referenced...
 Welcome to the RF Cafe
Frequency Mixers
Quiz, a technical assessment focused on the critical non-linear components that
enable frequency translation in transceivers and test equipment. Whether you are
designing heterodyne receivers, analyzing local oscillator (LO) leakage, or striving
to minimize spurious intermodulation products in your signal chain, a deep understanding
of mixer dynamics is indispensable for high-performance RF design. This quiz covers
the core principles of frequency conversion, exploring topics such as conversion
loss, isolation, port-to-port feedthrough, and the generation of mixing products.
By testing your grasp of these essential concepts, you refine your ability to optimize
your system's dynamic range...
 Way back in the 1980s while working at Westinghouse
Oceanic Davison in Annapolis, Maryland, an engineer who knew I had recently obtained
a 1941 Crosley Model 03CB console style radio generously gave me his
B&K Dyna-Quik Model 650 Vacuum Tube Tester. It is a very comprehensive
portable tester used by many professional radio and television servicemen. My tester
also had the Model 510 Accessory Socket Panel that added an ability to test 50%
more tube types. One indication that it is one of the later model tube testers is
the inclusion of a transistor testing socket. Unlike testing vacuum tubes, all of
which plugged into sockets to make them easily replaceable, testing a transistor...
 Punch cards have been used in computer systems
since the very early days of digital programming. They were probably the first form
of read-only memory (ROM), come to think of it. I hate to have to admit it, but
the meager computer used in my high school computer lab (circa early-mid 1970s)
used
punched cards. I never took the class, but stories abounded of
how pranksters would shuffle a stack of punch cards while the student programmer
wasn't watching and then get a good laugh when nothing worked. There are also
plenty of cases where a stack was inadvertently knocked onto the floor and had to
be laboriously re-ordered. IBM is the brand that comes to most people's minds
when thinking...
 As with my hundreds of previous
science and engineering-themed crossword puzzles, this one contains
only clues and terms associated with engineering, science, physical, astronomy,
mathematics, chemistry, etc., which I have built up over nearly two decades. Many
new words and company names have been added that had not even been created when
I started in the year 2002. You will never find a word taxing your knowledge of
a numbnut soap opera star or the name of some obscure village in the Andes mountains.
You might, however, encounter the name of a movie star like Hedy Lamarr or a geographical
location like Tunguska, Russia, for...
 Despite all the prefabricated, relatively
inexpensive products available these days, there are still many people who like
to build their own projects. Whether electrical or mechanical - or both - some sort
of
enclosure is usually involved. Often, you can cannibalize an existing,
retired project to use its chassis or find a product at Walmart or a home improvement
store that does not cost too much that you can buy just to get its enclosure. Buying
a pre-formed chassis for your project can get expensive, so there are times when
the best option is to obtain a piece of sheet metal (which can also be expensive)
and bend it yourself. If you have never attempted such an endeavor, believe me it
can be...
 Einstein's theories of relativity revolutionized
our understanding of space, time, and gravity. Special Relativity (1905) rests on
two postulates: the laws of physics are the same in all inertial frames, and the
speed of light in vacuum is constant for all observers. From these flow time dilation,
length contraction, relativistic mass, and the famous equation E=mc². General Relativity
(1915) extends these ideas to include acceleration and gravity by treating gravity
not as a force but as the curvature of spacetime caused by mass and energy. The
equivalence principle - that gravitational acceleration is locally indistinguishable
from inertial acceleration - is its cornerstone. Importantly, General Relativity
fully subsumes Special Relativity: in regions where gravity is negligible (flat
spacetime)...
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Loading history...
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.
 Engineers are entirely comfortable with numbers
multiplied by very large powers of 10; that is, with many trailing (or leading if
a decimal) zeros after the significant figures. A terahertz is 1 x 1012,
or 1 followed by twelve zeros, or
1,000,000,000,000 Hz. A picosecond is 1 x 10-12 s, or eleven
zeros between the decimal point and the one, or 0.000000000001 s. The mass
of the sun is approximately 1.9885×1030 kg, or 1,988,500,000,000,000,000,000,000,000,000 kg. The mass of an electron is approximately 9.10938×10-31 kg,
or 0.000000000000000000000000000000910938 kg. We don't even break a sweat when
punching those kinds of numbers into a calculator...
 This
passive
limiter is a simple combination of cascaded "T" type resistive attenuators that
are switched in and out of the circuit based on the power level in the line. The
design takes a bit of thinking due to needing to retain a reasonable impedance match
at the input and output throughout various stages' conduction states. Arriving at
an optimal value for resistors would require a circuit simulator with a mathematically
based optimizer, but, especially for amateur radio work, close is good enough. That
is not to say Hams are a bunch of slackers - they're not - it's just that component
and software resources are not as readily available (aka "prohibitively expensive")
for doing the analysis...
 Believe it or not, many countries did - and
some still do - charge people wanting to receive over-the-air (not cable or satellite)
commercial radio and/or television programming a
wireless license fee for the privilege. Yes, this is for receiving, not transmitting,
signals. If you dared to tune in a BBC program without a license, a fee could be
expected upon detection (pun intended). The Monthly Review feature in this 1946
issue of Radio-Craft magazine reported an increase in cost to the equivalent
of $29 in 2021 money (per the BLS Inflation Calculator). Also highlighted was a
method for printing radio circuits made with conductive inks on ceramic sheets -
known today as thick-film printing...
 By 1962, John T. Frye's techie troubleshooting
teenagers
Carl and Jerry had graduated from high school and were attending Parvoo University
(PU?) as electrical engineering students. It was a natural progression. Unlike many
of the company names and products - like the Delco DN278 transistor mentioned here
- that appeared in the Popular Science series, the college's name is fictional.
Maybe author Frye had a connection to Porvoo, Finland, and Anglicized the name.
Per RF Cafe visitor Jim P., "The stadium in the story is Moss-Ade stadium.
The stadium at Purdue University is Ross-Ade stadium. I would guess that Parvoo
comes from Purdue." According to a search I did to determine whether..."
 As mentioned in the past, most things you
might want to find from the present or past can be found eventually on eBay. Such
is the case with the Webster Electric Model 205 Tape Recorder mentioned in this
Mac's Radio Service Shop episode which appeared in a1954 issue of Radio &
Television News magazine. Here, Mac McGregor schools sidekick electronics technician
Barney Jameson on the workings of a high quality tape recorder, including some of
the ingenious methods devised for test and alignment. I especially like the magnetic
tape specifically prepared for head alignment by the Toogood Recording Company of
Chicago (yes, it was a real company, named after Mr. Louis S. Toogood)...
 Here is an advertisement for
Hytron Corporation that I scanned from page 83 of my copy of the June 1944
QST magazine. Hytron was a manufacturer of electron tubes. "So Many Owe
So Much To So Few," reds the title line. That is a paraphrase of Winston Churchill's
famous statement during World War II, "Never in the field of human conflict
was so much owed by so many to so few." That was in August 21, 1940, more than a
year before the U.S. entered the war. Perhaps of greater interest to RF Cafe visitors
are the next lines: "In peace, the Nation's debt to the radio amateur was great.
During hurricanes, floods, and other disasters, he sprang forward with emergency
communications. His endless...
 This 1952-era promotion for Bell Telephone
Laboratories describes what is essentially an early
Supervisory Control and Data Acquisition (SCADA) system; it's just that the
term had not been coined yet. SCADA systems uses sensors of various types to monitor
the status of critical parameters and report it back to a remote location via telephone,
cable, or radio links. It reduces or eliminates the need for personnel to be present
unless immediate human interaction is required to handle an adverse situation. Electrical
distribution stations, gas and oil lines, telephone switching installations, etc.
SCADA systems are typically monitored by computers and in most cases log events
and initiate required actions...
 As with on my Airplane and Rockets
hobby website, a big part of my motivation for scanning and posting these vintage
electronics magazine articles has been two-fold. The primary purpose is to provide
access to historical documents for research and educational reasons. The second
reason is to have the names of people and places published in text format (everything
OCRed) so that someone doing a Web search for himself, a relative, or a friend,
might run across it here. I receive e-mails occasionally from readers who are
thrilled to find those names in an old article, especially when the person
discovered has passed on and it serves as a fond remembrance. Features such
as...
 This
Technology Theme Crossword Puzzle for April 25th has many 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!
 Judging by some of the letters written to
magazines by their readers,
obtaining parts referenced in many construction articles proved difficult or
impossible to procure. Ziff-Davis, a major publisher in 1940 as well as today, ran
this notice in a 1940 issue of its Radio News magazine offering advice
as to how one might go about getting everything needed. Unlike nowadays where nearly
every available source worldwide can be found on the World Wide Web, back then searching
could be - and too often was - a long, slow process. Just finding a phone number
or mailing address for a potential supplier presented a major obstacle to anyone
without a collection of catalogs and magazines - or at least...
 Electronic mail did not start out as we know
it today, whereby anyone with access to an Internet-connected device can compose
and send a typed message to a similarly equipped receiver. The first electronic
mail message was sent (and received) on November 1, 1960, between post offices in
Washington, D.C., and Chicago, Illinois. This article from Popular Electronics
magazine takes you on a step-by-step tour of how the
Speed Mail system worked, including its dedicated shortwave radio links between
participating cities. Great care was taken in an attempt to assure message confidentiality
by having the letter opened and scanned automatically inside a sealed machine on
the transmit end ...
 After having read many articles about Dr. Lee
de Forest, it seems the poor guy was besieged his entire life by envious and/or
belligerent electronic communications compatriots who sought to defame him and/or
deny him of monetary rewards. This January 1947 issue of Radio-Craft
magazine includes a dozen or so pieces written by friends and colleagues who
recognized the momentous struggles and achievements of Dr. de Forest. Such
burdens of fame are borne by many - if not all - persons of similar celebrity.
Dogged persistence is the order of the day for experimenters and
breakers-through of assumedly impenetrable walls. Guys like de Forest lived by
the old adage recommending that "if at first you don't succeed...
 Here is a little electronics hobbyist humor
in the form a comic series titled "Hobnobbing with Harbaugh," compliments of
Popular Electronics magazine. Dave Harbaugh drew many comics for technical
magazines. For the non-Ham, QSL is the Q-code for "'I confirm that I received your
transmission." You don't need to be an amateur radio operator to appreciate these
comic strips, though. Note that with it being 1963, the husband and wife are shown
sleeping in separate beds - just like in the TV shows of the era like The Dick Van
Dyke Show and I Love Lucy. BTW, the kid in the crib is spelling out -..(d) .-(a)
-..(d) -..(d) -.--(y).
 It was a lot of work, but I finally finished
a version of the "RF &
Electronics Schematic & Block Diagram Symbols"" that works well with
Microsoft Office™ programs Word™, Excel™, and Power Point™. This is an
equivalent of the extensive set of amplifier, mixer, filter, switch, connector,
waveguide, digital, analog, antenna, and other commonly used symbols for system
block diagrams and schematics created for Visio™. Each of the 1,000+ symbols was
exported individually from Visio in the EMF file format, then imported into Word
on a Drawing Canvas. The EMF format allows an image to be scaled up or down
without becoming pixelated, so all the shapes can be resized in a document...
 Here are a couple more
electronics-themed comics from a 1940-era issue of Radio News magazine.
The scenarios depicted in these old comics are often based on the real-life experiences
of radio and electronics servicemen. No doubt many guys got clobbered by high voltage
or deafening audio when a customer decided to power up a television or radio while
being worked on in the home. When this comic with the police car radio appeared
in 1940, it had only been a decade since the first 2-way radios were being installed
in patrol cars (see "A New Arm of the Law"). A huge list of technology-themed comics
is listed at the bottom of the page. Enjoy! |
