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 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...
 These are the schematics and parts list
for vintage vacuum tube radios
Westinghouse Model H-133;
Arvin Models 150TC, 151TC; and
Admiral Model 7C63, Chassis 7C1 as they appeared in the December
1947 issue of Radio News magazine. I scan and post these for the benefit
of hobbyists and historians seeking such information. As time goes by, there is
less and less likelihood that records of these relics from yesteryear's archives
will be made available. As with all historical information, it takes someone with
a personal interest in preserving the memories in order to fulfill the mission...
 KR Electronics has been designing and manufacturing custom filters
for military and commercial radio, radar, medical, and communications since 1973.
KR Electronics' line of filters includes lowpass, highpass, bandpass, bandstop,
equalizer, duplexer, diplexer, and individually synthesized filters for special
applications - both commercial and military. State-of-the-art computer synthesis,
analysis, and test methods are used to meet the most challenging specifications.
All common connector types and package form factors are available. Designed and
manufactured in the USA. Please visit NIC today
to see how we might be of assistance.
 Here is another electronics quiz for you
to try. Intuition from experience goes a long way here, but if all else fails you
can work out the details of the rectifier circuits to determine
which lamp received the most current. Keep in mind that the diode
symbols are not LEDs; it is the "A," "B," and "C" symbols inside circles
that are the lamps whose brightnesses are being considered. LEDs did exist at the
time this quiz was created in 1969, but the circuits would perform differently if
in fact LEDs were used for double duty of rectification and illumination...
 The more things change, the more they stay
the same. That saying applies to many recreational activities. Pick up a copy of
QST magazine that was published in the last year and look at
reader comments and you will find laments about the dwindling
participation of youngsters, an increased degree of incivility and rule breaking
during engagement, the high cost of getting into the hobby, yadda yadda yadda. I
witness it regularly in the model aircraft world, too. That is not to say the issues
are not true or irrelevant, just that they are persistent. Each generation, it has
been said, tends to think...
 I have long-maintained that the vast majority
of electrical problems on consumer products can be attributed to bad connector or
switch contacts. Just yesterday, I restored a 1970's-era TI talking kids' toy to
working order just by cleaning the plug-in program module and mating motherboard
contacts. RF Cafe website visitor / contributor Bob Davis sent this suggestion for
curing intermittent or non-responsive front panel buttons on test equipment and
other electronic gear like radios, remote keypads, games, tools, vehicles, keyboards,
locks, etc. His problem was with a R&S spectrum analyzer. He found a solution
from ButtonWorx, who manufactures replacement
pressure contacts for a large range of products. Some are entire arrays to replace
original parts, and others are individual switches for custom requirements.
 You wouldn't know it from the schematic,
but this
Coronet
Model C-2 tabletop radio has a very unique feature: The tuning scale/pointer,
and volume and tuning knobs are on the top of the case, that is, the face of the
radio points upward when properly displayed. When searching for photos of the Coronet
C2, I found a few examples where the radio was sitting on a surface with the face
situated vertically like a standard model, but the feet are clearly on the side
opposite the face. The schematic and parts list for the Coronet C2 radio appeared
in the February 1947 issue of Radio News magazine. There are still many
people who restore and service these vintage radios, and often it can be difficult
or impossible to find schematics and/or tuning information. I keep a running list
of all data sheets to facilitate a search...
 Have you noticed that every time a shooting
or other attack event occurs - especially pertaining to "R" targets - the quality
of the video looks like something from the 1970s, or of a UFO sighting? Most private
surveillance cameras in homes, cars, and businesses - even traffic cams - have resolution
and full color so good you can distinguish faces and even identify brands of clothing,
weapons, etc. This is a frame from the attempted assassination attempt this weekend
at the White House Correspondents Dinner. The perp, a celebrated "Teacher of the
Month" from California, rushed the security point with multiple weapons. Conceal
carry, do training, and watch your six.
 In the early 1950s, the U.S. Navy built
what was at the time the world's largest and most powerful radio broadcast transmitter
station at the
Jim Creek Naval Station on Wheeler Mountain in Washington state.
Its 1.2 MW, 24.8-to-35 kHz VLF transmitter (call sign NLK) can reach anywhere
in the world, even to submarines. A half wavelength at 24.8 kHz is 19,830 feet.
Photos indicate that the transmitter is located in the middle of a dipole arrangement.
"Catenary cables," if you are unfamiliar with the term, refers to the sagging shape
assumed by both the antenna cables and the tower support cables. "Catenary" stems
from the word "chain" since it is in the form...
 Carbon tetrachloride (CCl4) was
a common cleaning agent used commercially through about the early 1950s when it
began receiving a lot of bad press due to a linkage to severe kidney damage from
exposure even in vapor form. I notice that Mac mentions having read an article about
the potential danger of "carbon-tet" in an edition of Radio & Television
News magazine, not coincidentally the publication where the "Mac's Radio Service Shop" series appears. He also mentions a publication
called International Projectionist, which included instructions for cleaning
movie film with carbon tetrachloride, and had...
 It is amazing to me how many times I read
an article, whether in a vintage magazine like this 1947 issue of Radio News,
or a current edition of QST, how when discussing maximum power transfer
from a source to a load, the author states merely that the load impedance must equal
the source impedance. The fact of the matter is that the source and load impedances
must be the
complex conjugates of each other in order for maximum power transfer
to occur. That is to say that if the source has a complex impedance of R + jX, then
the load must have a complex impedance of R - jX (and vice versa)...
 Unlike today when resources of all types
seem to be endlessly available, during World War II countries needed to collect
and recycle much in the way of metal, rubber, cloth, and other basic materials for
re-purposing into products used in fighting the enemy. Media coverage of bottle,
metal, and tire drives showed children pulling Radio Flyer wagons loaded to overflowing
with such items gathered from trash piles and soliciting neighborhood residents
for anything that could be spared. Raw materials were not the only type of items
needed, however. "Use
it up, Wear it out, Make it do, or Do without" was the slogan. Finished goods
like electronic components - vacuum tubes, transmissions cable, transmitters and
receivers, tuning capacitors, d'Arsonval meter movements, and other parts -
were sorely needed by manufacturers both for building new equipment and for servicing
damaged gear. After the war was won, the War Assets Administration...
 Around the time when this "The
Great QSL Quarrel" appeared in a 1960 issue of Electronics Illustrated
magazine, there was a long-standing friction between amateur radio operators and
shortwave listeners regarding the exchange of QSL confirmation cards. Far from mere
paper, many hams view their custom-designed cards as valuable reflections of their
personal rigs and efforts. Consequently, they often discard subpar listener cards
that are illegible, aesthetically dull, or lacking meaningful data. To ensure their
reports are actually welcomed, shortwave listeners are urged to adopt higher standards:
utilizing professional printing or clear handwriting...
 A momentous development that changed the
field of radio communications warranted merely a half-page announcement in 1935
when
frequency modulation inventor Edwin Armstrong had his article
published in Radio-Craft magazine. It indisputably changed the world while causing
poor Mr. Armstrong much grief while defending his right to the invention. Spread
spectrum modulation / demodulation would be the next big communications advance
that began with the frequency hopping (FHSS) scheme dreamed up by Hollywood actress
Hedy Lamarr and pianist Antheil George during World War II. Direct sequence
spread spectrum (DSSS) followed in the digital age, and since then I do not know
of any fundamentally new communications technology in that time...
 Since 2005, San Francisco Circuits has been
a trusted U.S. provider of advanced PCB manufacturing and assembly solutions for
R&D innovators, prime contractors, and integration experts.
Flying Probe Testing (FPT) has long been a reliable method for validating PCB
designs, particularly for prototypes and low volume production. Unlike traditional
in circuit testing (ICT), which relies on custom built fixtures, flying probe systems
use movable probes to test electrical connections directly, eliminating the need
for dedicated hardware. Flying probe testing uses multiple programmable probes to
contact pads...
 The February 1947 issue of Radio News
only had two
electronics-themed comics. Many months have up to half a dozen
comics. Maybe the winter blues had set in with the magazine's illustrators. The
first comic is a tad bit prescient in that it depicts a robber running past a television
store and seeing a TV in the front display window showing a real-time video of the
cop chasing him. That was way before there was a video surveillance camera on every
street corner. I haven't discovered a vintage magazine yet with someone taking a
"selfie." There is a growing list...
 These are the schematics and parts list
for vintage
Emerson vacuum tube radio models 501, 502, and 504;
Crosley model 56TD-W; and
Arvin model 140P as they appeared in the November 1947 issue of
Radio News magazine. I scan and post these for the benefit of hobbyists
and historians seeking such information. As time goes by, there is less and less
likelihood that records of these relics from yesteryear's archives will be made
available. As with all historical information, it takes someone with a personal
interest in preserving the memories in order to fulfill the mission...
 John Comstock created many crossword puzzles
for Radio & TV News magazine, and a couple others, in the 1950s and
1960s. This one titled "Test
Equipment Teaser," appeared in the March 1959 issue. It is not a densely populated
grid with complex intersections of crossing words (unlike the RF Cafe crossword
puzzles, which do have them), but at least with this kind, all of the words and
clues are directly related to electronics and technology (like RF Cafe crosswords).
Anyway, it shouldn't take you too long to zip through this one. The only clue/word
that might give you trouble is 32 Across. Enjoy...
 Exodus Advanced Communications' representatives,
in discussions during last month's EMV (Elektromagnetische Verträglichkeit) show
in Cologne, had many attendees express interest in receiving an Exodus brochure
covering our RF amplifier solutions for
drone (UAS) applications. Exodus supports defense contractors with a family
of RF amplifier modules optimized for UAV, drone, mobile, and fixed Counter-UAS
platforms. At the center of this portfolio is the
AMP10008, an ultra-lightweight solid-state RF amplifier module
that demonstrates what is possible when SWaP is treated as a primary design driver
rather than a compromise...
 The cover of this month's Radio &
Television News magazine is part of the issue's story on performance testing
of resistors. The author was an engineer for
International Resistance Company (IRC), which is still in business
as part of TT Electronics. The massive ovens were used for load-life testing to
certify resistor products for both military and commercial uses. When required,
humidity enclosures subjected resistors to increased levels to test for insulation
breakdown at high voltage. As the article observes, since a 10-cent resistor can
take down a multi-thousand system, it is important to guarantee every component's
integrity...
 Werbel Microwave is a manufacturer of RF
directional and bidirectional couplers (6 dB to 50 dB) and RF power dividers
/ combiners (2- to 16-way) with select models operating up to 26.5 GHz and
100 W of CW power (3 kW peak). All are RoHS and REACH compliant and are
designed and manufactured in our Whippany, NJ, location. Custom products and private
label service available. Please take a couple minutes to visit their website and
see how Werbel Microwave can help you today.
 RF Cafe's spreadsheet-based engineering
and science calculator,
Espresso
Engineering Workbook™, is a collection of electrical engineering and physics
calculators for commonly needed design and problem solving work. The filter calculators
do not just amplitude, but also phase and group delay (hard to get outside of a
big $$$ simulator). It is an excellent tool for engineers, technicians, hobbyists,
and students. Equally excellent is that Espresso Engineering Workbook™ is provided
at no cost, compliments of my generous sponsors. 49 worksheets to date...
 Although the Japanese attack on Pearl Harbor
on December 7, 1941, was a complete surprise and shock to the nation, that fact
that the United States would eventually be drawn officially into World War II
was well known. The amateur radio community had begun talking about the potential
impact on radio communications hobbyists earlier in the year, as evidenced by articles
printed in QST and other magazines. Within a couple weeks of Congress declaring
war, all unauthorized transmissions from Ham stations were terminated in order to
prevent both intentionally and unintentionally conveyance of information that could
proves useful by the enemy. Along with being a patriotic bunch that were eager to
help defeat Axis powers, they also...
|
 • U.S.
Engineering
Ph.D. Programs Losing Students?
• What
Hormuz Exposed About Semi Supply Chain
• Broadband
Equipment Market Set for 2026 Rebound
• Foundry
Revenues to Grow 24.8% YoY
• U.S.
Manufacturing Sector Flexes Its Muscles
 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.
 While this article is directed at amateur
radio operators who want to explore working in the microwave bands, it is good fodder
for anyone who wants a fundamental introduction to
waveguides, resonant cavities, distributed elements, and atmospheric propagation.
If that describes you, and particularly if you have formulaphobia, then start reading.
Even though the article appeared in a 1952 issue of Radio & Television News,
the list of frequency band allocations are not much different than today so the
information is useful. Unknown to many is that in the early part of the last century
Amateurs pioneered the use of microwave bands when the Federal Communications Commission
(FCC) allocated the spectrum to them since many "experts" considered it unusable...
 At least 10 clues with an asterisk (*)
in this
technology-themed crossword puzzle are pulled from this past week's (6/18 - 6/22)
"Tech Industry Headlines" column on the RF Cafe homepage. For the sake of all the avid
cruciverbalists amongst us, each week I create a new technology-themed crossword puzzle
using only words from my custom-created related to engineering, science, mathematics,
chemistry, physics, astronomy, etc. You will never find among the words names of politicians,
mountain ranges, exotic foods or plants, movie stars, or anything of the sort. You might,
however, see someone or something in the exclusion list who or that is directly related
to this puzzle's theme, such as Hedy Lamar or the Bikini Atoll, respectively. Enjoy...
 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...
 Remember when the first manned spacecraft transported
astronauts to Mars and then back to Earth in the 1970s - a 13-month round trip? In
the mid-1960s, Electronics magazine reported on the preparations being made
by NASA for Mars travel at the same time they were busy preparing the Apollo mission
to the moon. The world's first manned orbit (Apollo 8) of the moon didn't happen
until in December 1968, a mere seven months before the historic July 1969 Apollo 11
moon landing*, but NASA was wasting no time planning for the next big thing. Of course
you know to date we never have made it to Mars with a manned spacecraft, but the headlines
are still filled with "any day now" projections by SpaceX's Elon Musk (whom I
like) and his contemporaries. Sure, I would love to be alive to witness a manned
mission to Mars, but I'd settle...
 This second in a series of
International Geophysical Year (IGY) articles that appeared in Radio-Electronics
magazine in 1958. The author covers basics of satellite configuration, launching,
and tracking based on knowledge of the era. Keep in mind, though, that the U.S.
had not actually launched its first satellite at the time. In fact, the two satellite
models shown possess antennas suggesting active radio circuits within, but Echo,
our first passive earth-orbiting satellite, was just a metallized plastic sphere
that reflected radio signals back to Earth. The Russian Sputnik, by comparison,
did have electronic circuitry onboard for transmitting but not receiving a signal.
SCORE, launched in December of 1958, was America's first transponder satellite...
 If you had $4,000 to spend on a
desktop computer today, your money would get you a top-end 8-core microprocessor
with at least 32 GBytes of super-fast RAM, a couple TBytes of solid state hard drive
space, and at least a 32" high definition screen monitor. It would be a top-of-the-line
machine any serious gamer would envy. In 1982, the same cash would also get you
a top-of-the-line computer, but it would have a 1-core processor, a whopping 768
KBytes of sub-MHz RAM, a 10 MByte hard disk drive, and a 12" monochrome display.
That describes the IBM PC, Tandy's TRS-80, as well as the Zenith Z-100 PC shown
here from the Heathkit 1982 Christmas catalog. If you were around back then...
 Sitting in the waiting room in the local Jeep dealership,
waiting for the technicians to do the annual inspection on the 2011 Patriot, I noticed
a 12 volt car battery sitting on a table. At first I assumed it was just a sales pitch
for a new battery, but then I noticed a bunch of small cables coming from its bottom
edge. As you can see in the photo I took of it, those cables are mobile device charging
cords with mating connectors for Apple, USB, and miniUSB ports. An Internet search did
not turn up any of these things, so maybe Mopar engineers came up with it. Times sure
have changed from when...
 Major Edwin Armstrong, whose first name
is Edwin but is often assumed to be Major (which used to be a not-so-rare man's
first name), was endowed with many awards, patents, titles, and honorary distinctions
during his amazing career. He served in the Signal Corps during World War I,
where he attained the rank of Major. Having already achieved notoriety for his work
prior to being commissioned, he entered as military service as a Captain (RCA's
David Sarnoff was initially commissioned as a General during World War II).
Being highly patriotic, Armstrong granted the U.S. government free use of his patented
material during both wars. As with many other renown inventors, scientists and engineers
of the era (and no doubt today as well), he suffered from personal issues that haunted
him constantly, as written about in my Kirt's Cogitations article...
 In 1957, when these
communications-themed comics appeared in Radio-Electronics magazine,
home-based entertainment electronics was a big deal. Installing a major media setup
with a stereo system and/or a television served to prove your technical prowess
and hopefully set you up as the neighborhood expert. That fad continued for a few
decades, but by now even the most sophisticated equipment is self-configuring and
requires little more effort for success than setting it where you want it in the
room. Artificial intelligent (AI) uses Bluetooth and WiFi to evaluate the surroundings
and adjust accordingly. Your typical Walmart system might not have that capability,
but if you're shopping at Walmart for your media gear, you're not really qualifying
your setup as high end. These comics do a pretty good job of conveying the mood
of the era...
 Here is a Christmas-themed "Carl & Jerry" episode from the December 1958 issue of
Popular Electronics magazine. Carl and Jerry, if you are not familiar with
them, are a couple electronics-savvy teenagers who, in the style of "The Hardy Boys,"
manage to get involved in a series of criminal investigations. With headquarters
based in their parent's basement, the two friends cobble up strategies and contraptions
for snaring bad guys, bedazzling unsuspecting neighbors and classmates, and assisting
people in need of techno-capable assistance. They have quite an impressive collection
of test equipment and radio gear at their disposal per the one drawing herein. In
this episode we are introduced to the word "osculation." If you already knew its
definition, you're one up on me...
 As a case in point about my claim with an
earlier post featuring Bob Berman's factoids on astronomy, this article from a 1956
edition of Popular Electronics illustrates how vital electronics are in
the various fields of science. It has only been fairly recently that astronomers
have been "looking" at stars and planets outside of the visible wavelengths. Renditions
of the sky in both shorter and longer wavelengths show in some regions a vastly
different universe. In 2015, a comprehensive mapping of the entire known universe
in the microwave realm revealed the largest contiguous feature ever detected - dubbed
"The Cold Spot." Such discoveries could not be made without sophisticated electronics.
The same can be said of medicine, biology, mechanics, finance, etc. Reported here
are some of the earlier detections of radio signatures from our planets...
 Back in the 1960s, Robert Balin created many
quizzes on various electronics topics for Popular Electronics magazine.
I have posted many of them (see complete list below). This one from the May 1962
issue is on the subject of
units of measure commonly found in electronics work. All are still found in
modern devices, so you don't need to be an expert on vacuum tubes and selenium rectifiers
to get a good score. I missed the one for the tape deck, but then I don't ever remember
concerning myself with the electrical and magnetic characteristics of tape decks.
Maybe you will do better.
 This is the electronics market prediction for
Russia, circa 1966. It was part of a comprehensive assessment by the editors of
Electronics magazine of the state of commercial, military, and consumer
electronics at the end of 1965. Then, as now, Russian electronics products are
not considered to be serious competition to U.S. markets. For that matter, when
is the last product of any type you bought with a "Made in Russia" stamp on it?
Even though the Soviet Iron Curtain fell in 1992, very little progress has been
made with mending fences with them. Unless you can find a news story on the
state of the industry, detailed reports must be purchased from research
companies...
 I have been scanning and posting schematics
and parts lists like this one featuring the Admiral (full name Admiral Continental
Radio & Television Co., located in Chicago, IL) models
7T06 and 7T12 in graphical format. It appeared in a 1947 issue of Radio News
magazine. Publications of the era provided this service data for the sake of both
professional repairmen and hobbyist do-it-yourselfers because the manufacturers
did not make it available to entities that were not official representatives. Sams
Photofact made more detailed documentation available for sale, but it was expensive.
There are still many people who restore and service these vintage radios, and often
it can be difficult or impossible to find schematics and/or tuning information.
I will keep a running list of all data sheets to facilitate a search. An Admiral
7T06 radio recently came up for sale on eBay...
 "QRM" is the Q-code in Ham-speak for unwelcomed
manmade inband electrical interference. Interference is not just random signals
like noise from motor brush arcing, intermittent electric distribution system connections
or inter-conductor arcing, etc. An improperly tuned or ineffectively filtered radio
transmission, or EM energy leaking from a poorly shielded electronic device is also
QRM. I distinguish such noise as unwelcomed because what might be considered as
noise by one person could be a desired signal by another. "QRN" stands for electrical
noise generated in nature such as lightning bolts, solar storms, or even, as discovered
by Drs. Arno Penzias and Robert Wilson, the 160 GHz Cosmic Microwave Background
(CMB) radiation that emanates from all regions of the sky. A mnemonic for remembering
which Q-code is which is the trailing "M" for manmade and "N" for natural...
 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 Frye ever attended
Purdue, "Remarkably enough, he never attended Purdue University..."
 RF Cafe visitor Kevin A., of Roanoke,
VA, sent me this article from the September 1972 edition of the American Radio Relay
League's QST magazine. He was motivated to send it after reading some of
the articles I posted from WWII era QSTs. We can all probably relate a
story similar to the one told here. How many "Old Al" types - the
antithesis of an "Elmer"
- are out there who knowingly or unknowingly frustrate others from participating
in an otherwise fun activity because he insists on beating up on a trivial topic
ad nauseam? You can feel the angst in the author's voice while reading. Ray, are
you out there? Is this story real or fictitious? It could easily be either...
 By 1946,
radio and television manufacturers were scurrying to supply the huge, pent-up
demand for communications and entertainment systems that accumulated during World
War II. Fortunately, the dearth of electronics components, raw materials for
chassis fabrication, and available labor was suddenly and significantly turned around
by late 1945. Wanton destruction of entire cities in Europe left citizens without
many basic creature comfort items like radios, televisions, refrigerators, vacuum
cleaners, toasters, automobiles, and other things taken for granted a decade earlier.
As with any well-executed plan, manufacturers endeavored to survey the market demand
for such products and then devised a way to satisfy that demand. Radio News
magazine published a synopsis in mid-1946 of the state of the radio and television
industry in Europe so that companies...
 In the days before just about every multimeter
had a built-in
diode and transistor tester, there was not much - if anything - available for
the hobbyist. Some of the vacuum tube test sets, like my 1961 vintage B&K Dyna-Quik
Model 650, surprisingly included diode and transistor test sockets. This article
for a "non-destructive" type - as opposed to the popular "destructive" type -
homebuilt transistor tester appeared in a 1971 issue of Popular Electronics
magazine. It can identify PNP vs. NPN, measure DC gain, and measure leakage
current. The tester will verify diode integrity as well. There's also a bonus
"Parts Talk" comic on the page at no extra cost... |
