|
 Radio-Electronics magazines'
"Service Digest" column regularly reported on issues relevant to the electronics
servicemen who repaired radios, television sets, phonographs, recorders, and similar
items - often in the customers' homes. Then, as now, professionalism and courteous
behavior was often rewarded with word-of-mouth referrals to friends and relatives,
resulting in new business opportunities. An interesting topic also included was
the need to observe extreme caution when working around TV tubes (CRT's) not
just because of the lethally high voltages present, but because of the
danger of tube implosion and the resulting scattering of glass
shards. An example given is that due...
 Prior to the advent of
FET-input multimeters, obtaining a very high input impedance meter
required the use of a vacuum tube circuit that used a buffer stage to isolate the
measured signal from the loading effects of the meter movement. As most people reading
this article already know, the voltage value indicated by a non-buffered meter can
be greatly affected by the meter's loading of the device under test (DUT) if
the meter's impedance is not many times greater than the DUT's impedance.
The voltmeter is used in parallel with the circuit under test, so for example if
the impedance of the DUT is 100 kΩ and the meter's impedance is also 100 kΩ,
the meter will display a value as if the DUT...
 RF Cafe visitor Brad B. just provided
the following
Watkins-Johnson Tech Notes for the collection: v5-3, v5-4, v5-5,
v5-6, v6-2, v6-3, v6-4, v6-5, v6-6, v8-1, v8-4, v9-1, v9-2, v9-3, v9-4, v9-5, v10-2,
v10-5, v10-6. They run the gamut from Solid State Limiting Amplifiers and Antenna
Polarizations to Digital Signal Processing for Multichannel Receiving Systems. Many
old-timers consider the W-J Tech Notes to be some of the best sources of circuit
and systems design guides ever written, especially for military, defense, and aerospace
applications. Waaaaay back in the 1970s and 1980s when I was new to the electronics
design world, offices, cubicles, laboratories, company...
 I'm not sure how much
mechanical filters are used in circuit design these days due to
their somewhat large size and complexity. They typically exhibit a high "Q" with
a relatively flat passband (with some ripple) and very sharp cutoff in the skirts,
and the insertion loss is low compared to lumped element equivalents (for comparative
out-of-band cutoff). Operational frequencies were limited to a few hundred kilohertz,
so they are useful only at intermediate and baseband frequencies. This article,
appeared in a 1953 issue of Radio-Electronics magazine, describes the basics of
mechanical filter design and construction. Mechanical filters from aircraft radio
manufacturer Collins and other can be...
 Temwell is a manufacturer of 5G wireless communications filters
for aerospace, satellite communication, AIoT, 5G networking, IoV, drone, mining
transmission, IoT, medical, military, laboratory, transportation, energy, broadcasting
(CATV), and etc. An RF helical bandpass specialist since 1994, we have posted >5,000
completed spec sheets online for all kinds of RF filters including helical, cavity,
LC, and SMD. Standard highpass, lowpass, bandpass, and bandstop, as well as duplexer/diplexer,
multiplexer. Also RF combiners, splitters, power dividers, attenuators, circulators,
couplers, PA, LNA, and obsolete coil & inductor solutions.
 The most effective method for
isolating DC power traces, low-frequency analog signal traces, high-frequency analog
signal traces, and digital signal traces on a multi-layer printed circuit board
is not simply to "separate everything with gaps." The best-practice method is functional
partitioning combined with continuous, carefully assigned reference planes, controlled
return-current paths, localized power distribution, and layer stackup planning.
In practical PCB design, signals do not travel only in copper traces. Every signal
current has a corresponding return current, and at higher frequencies that return
current follows the path of lowest impedance, usually directly under...
 In this episode of John T. Frye's
"Carl & Jerry" series, the intrepid pair of teenage electronics hobbyists and
Ham radio operators are experimenting with an audio amplifier rig that uses a parabolic
dish for concentrating sound waves at a focal point where they have a microphone
mounted. Aside from picking up bird noises and a neighbor lady scolding her husband
for not properly washing the windows during a round of Spring cleaning, Carl imposes
upon Jerry for a lesson in
feedback techniques - both positive and negative - and the reasons
one is preferred over the other. The story winds up with a clever double entendre
comment referring to osculation...
 We all know that for the most part television
stinks. Back in 1951 when this article appeared in Radio-Electronics magazine,
the technology was very new and it was considered a miracle not to be wasted on
inane programming. Newscasts actually presented news and not opinion, movies and
sitcoms cast the nuclear family, law enforcement, the military, religion, and patriotism
in a positive light rather than as the purveyors of evil in the world. By the end
of the 1960s to early 1970s a lot of that had changed. Political and social agendas
weaseled their way into nearly all programming to the extent that terms like "boob
tube" and even, yes, "smellivision," became common monikers for television...
 "Are we killing the broadcasting goose, layer of many golden eggs?"
Dr. Lee de Forest asked in his inaugural address, upon his election to the presidency
of the Institute of Radio Engineers. So went the opening editorial in a 1930 edition
of Radio News magazine. It was directed at the question of whether excessive,
"gratuitous" advertising was going to be so offensive to listeners that they would
turn off the set and go back to their former silent worlds. Remember that many,
if not most, households, and certainly not automobiles, even had radios at the time.
Building an audience was essential to nurturing the new phenomenon of radio, and
to saturate the listeners with commercials would surely doom...
 Here are three more
technology-themed comics from vintage of Radio & Television
News magazines. Some issued had multiple comics, but these three had just one
apiece, so I combined them onto a single page. There is a huge list of previously
posted comics at the bottom of the page. With many of these comics, you might need
to be familiar with the mindset of the electronics world back in the day. Today
it considered hilarious today to see a video of someone walking into a street lamp
pole while staring obliviously into a smartphone. In the middle of the last century,
fun was made of wives not understanding their hubbies' hobbies, dealings with servicemen,
and and goofy things do-it-yourselfers...
 Amplifier Solutions Corporation (ASC) is
a manufacturer of amplifiers for commercial & military markets. ASC designs
and manufactures hybrid, surface mount flange, open carrier and connectorized amplifiers
for low, medium and high power applications using Gallium Nitride (GaN), Gallium
Arsenide (GaAs) and Silicon (Si) transistor technologies. ASC's thick film designs
operate in the frequency range of 300 kHz to 6 GHz. ASC offers thin film
designs that operate up to 20 GHz. ASC is located in an 8,000 sq.ft. facility
in the town of Telford, PA. We offer excellent customer support and take pride in
the ability to quickly react to evolving system design requirements.
 In the days before people were so easily
offended by light-hearted poking, it was not uncommon to find magazine articles
written by the wives of hobbyist husbands lamenting the habits and proclivities
of their matrimonial mates. Over the years I have read many such treatises in model
and full-scale airplane, electronics, and Ham radio publications. As with "A Radioman's Wife Puts in a Good Word" from a 1951 issue of
Radio-Electronics magazine, they typically start by expressing frustration
of having lost their once-doting husbands to alternative loves in the form of hobbies
(I once saw a boat named "The Other Woman"). Determined to win back the devotion
of their sweethearts, they...
 Most people who have been in the electronics
world for a while know that neon light bulbs* used to be commonly employed as a
"pert-near" voltage regulator reference of between 55 and 65 volts, depending on
the type. The familiar NE-2 has a turn-on voltage of 65 Vac (90 Vdc),
for instance, and the voltage across the terminals remains there with little change
regardless of the current through the bulb - a lot like a Zener diode. Neon bulbs
are also used as non-invasive RF power detectors. Most people probably do not know,
however, that incandescent bulbs also have properties that make them useful for
purposes other than just lighting up a dark space.
Incandescent light bulbs have...
 This newest edition to RF Cafe's *FREE*
Espresso Engineering Workbook was a major bit of work. The ABCD-,
s-, h-, T,- Y- Z- Parameter Conversions worksheet will convert a
2-port
matrix of any of those types of matrices into the equivalent of all the others.
Enter the real and imaginary parts and click the appropriate button. I do not know
of any similar FREE conversion facility. True, the vast majority of visitors will
never need to perform such conversions, but for those who do, well, here you are.
My first exploit with them was way back around 1990 when writing a DOS program to
do a cascade calculation of components whose s-parameters were known, but needed
to be converted to an ABCD matrix for simpler calculation...
 Since 2000 - that's 20 years - I have
been creating custom
technology-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 village in the Andes mountains.
You might, however, encounter the name of a movie star like Hedy Lamarr or a geographical
location like Tunguska...
 Here is Part 14 of a series entitled
"The Saga of the Vacuum Tube," by Gerlad Tyne, that appeared in
Radio News magazine in 1944. Part 1 was printed in March 1943, and Part 22,
the final chapter, was published in April 1946. It could have been a stand-alone
book. If I manage to be able to buy issues with some of the other parts, those will
be posted as well. You might be aware of the origins of the amplifying vacuum tubes,
beginning with the accomplishments of Dr. de Forest and his Audion. As with
most new technologies, progress moved very rapidly once other researchers glommed
on to the concept. Here, Mr. Tyne discusses the development of the "Kenotron,"
"Pliotron"...
 Electronics wizard, repairman, and experimenter
extraordinaire Mac McGregor, as sort of alter ego of author John T. Frye, provides
a brief lesson on electrostatics for his repair shop apprentice wing man Barney
(I don't think his last name was ever mentioned). In this 1973 Popular Electronics
magazine article, Mac had built two types of
electroscopes - one using a pair of pith balls suspended from
silk strings and another that was a cobbled-together version of a gold leaf electroscope.
His motive was two-fold. First and foremost was to accommodate his own interest
in electrostatics, and second to hopefully engender enough curiosity in Barney to
cause him to do a dive into science books...
 Citizens Band Radio (CB) in the United States
grew out of the post-World War II idea that ordinary citizens, small businesses,
farmers, contractors, hunters, motorists, and families should have access to short-range
two-way radio without the technical qualifications required for amateur radio. The
Federal Communications Commission created the Citizens Radio Service in the 1940s,
initially in the UHF region, but CB became culturally important only after the FCC
opened the 27 MHz "11-meter" band to Class D Citizens Radio in 1958. That band,
26.965 MHz to 27.405 MHz today, is what most Americans mean by "CB radio.” CB was
originally licensed. Users paid for an FCC license...
|
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.
 How RF circuits work have long been referred
to as "black magic," even sometimes by people who fully understand the theory behind
the craft. To me, the ways in which a transmission line - be it coaxial cable, microstrip,
or waveguide - can be manipulated and controlled with various combinations of lengths
and terminations is what most qualifies as "magic." Sure, I know the equations and
understand (mostly) what's happening with incident and reflected waves, etc., and
how the impedance and admittance circles of a
Smith chart graphically trace out what's happening, but you have to admit
there's something mystical about it all. Fortunately, Mr. John...
 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...
 The
G-Line (aka G-String) RF transmission system is a rather amazing invention contrived
through out-of-the-box thinking by its inventor, Dr. George Goubau (from whence
the "G" in the name derives). He determined that a sort of waveguide could be made
with a single conductor surrounded by insulation with a specific dielectric constant
that would cause the dielectric-air interface to reflect the wave in a manner similar
to atmospheric channels that facilitate long distance communications. The G-Line
is designed to efficiently transmit UHF television signals (470 - 806 MHz),
and like a waveguide exhibits a lower cutoff frequency (~300 MHz), thus acting
like a...
 While not many people are likely to build
this
R-C bridge circuit with vacuum tubes for use during design and troubleshooting,
this 1947 Radio News magazine article has a good basic description of operation
of any calibrated bridge circuit used to measure an unknown value. Interestingly,
a "magic eye" or "cat's eye" tube is used in lieu of a meter movement to give a
visual indication of an open, short, intermittence, poor power factor, and low "Q,"
as well as when the selected switch position correctly identifies the value of the
resistor or capacitor under test. Note that in that era μfd = μF and μμfd = pF...
 It
is the opinion of historians that in order to understand the present, you need to
know the past. Searching for one's roots in this world is big business. Online family
tree type websites are used by thousands of people to research their family histories,
and some services don't come cheap. You can even pay someone to dig into your past
to assimilate all available information and put it in a bound, printed volume. Here
on RF Cafe, I research and post a lot of our profession's past.
While the individual topics themselves might no bear significantly on the
present, having an insight into the people's mindsets and progression of
technology is...
 For a long time I have been scanning and
posting schematics & parts lists like this one featuring the
International Kadette Model 400 4-Tube Battery-Operated Superheterodyne radio
in graphical format. As with all the other vintage articles posted, it requires
running OCR on them to separate the textual content from the graphics. This particular
Radio Service Data Sheet came from the July 1936 issue of Radio-Craft 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 will keep a running list of all data sheets to facilitate a search...
 Often, the photo on the covers of magazines
is related to a feature article within, but in the case of the March 1954 Radio-Electronics,
only a couple paragraphs are devoted to it. Although more commonplace back in the
day, mention of a
Lecher wire for measuring VSWR values of the antenna under test caused me to
look it up. The Wikipedia entry says, "Lecher line or Lecher wires is a pair of
parallel wires or rods that were used to measure the wavelength of radio waves,
mainly at VHF, UHF and microwave frequencies. They form a short length of balanced
transmission line (a resonant stub). When attached to a source of radio-frequency
power such as a radio...
 AC alternators replaced DC generators back
in the 1940s as demand for conditioned electrical power in vehicles rose beyond
that needed for ignition and lighting. Radios are the most notable additions, and
because amplitude modulation (AM) broadcasts were the dominant method of the day
for commercial stations, noiseless electrical supplies were required. Spark-induced
noise from ignition systems was bad enough since its frequency varied with engine
RPM, but the DC generator's commutator sparking noise - much of it right smack in
the audio frequency range - was just too much for the public to endure if widespread
acceptance of radio was to be...
 In a continuing effort to provide archival
material for researchers and for anyone seeking information on a particular radio
restoration project, this Radio Service Data Sheet for the
Crosley "Chief" Model 132-1 radio from a 1933 edition of Radio-Craft is being
posted. An Internet search will show that there are many people engaging in such
activities. Restoring my Crosley Model 03BC console radio would have been more difficult
if not for others who have done similar work to assist the "community." I generally
despise the phrase "giving back" because it is usually uttered by people that really
owe nothing to anyone, but somehow feel obligated to do so or are...
 The January 2016 issue of Scientific
American ran an article by Clara Moskowitz titled "Elegant Equations" that presented
a few prints from "The Concinnitas Project" which "...is a collection of ten aquatints
produced from the contributions of ten mathematicians and physicists in response
to the prompt to transcribe their 'most beautiful mathematical expression.'" The
renowned mathematicians and scientists who contributed to the project are Michael
Atiyah, Enrico Bombieri, Simon Donaldson, Freeman Dyson, Murray Gell-Mann, Richard
Karp, Peter Lax, David Mumford, Stephen Smale, and Steven Weinberg. My personal
favorite is...
 These days it is probably rare that a person
would find the need to construct a custom
transformer for a power supply since just about anything you need can be found
on websites like eBay and Amazon. However, there are still many homebrew types out
there who enjoy the challenge (and maybe nostalgia) of creating a transformer for
a special need. For those folks, this article from a 1952 issue of Radio-Electronics
magazine will be a welcome bit of information. Author T.W. Dresser presents
the fundamental equations and design methodology needed for winding a transformer
on a laminated steel core frame. There are plenty of abandoned transformers which...
 Transistors were still relatively new when
these cartoons were published in the September 1959 issue of Popular Electronics
magazine. Most people had never seen a transistor, much less handled one.
Soldering irons used for working on the point-to-point wiring used on vacuum
tube gear could also be used for soldering the old copper guttering and
downspouts - at least the ones that got hot enough and had enough thermal
inertia to melt solder on sheet steel chassis'. Does the guy in this
General Transistor infomercial look a bit like Dilbert - or maybe I should
ask does Dilbert look a bit like this guy? BTW, are you thinking what I'm
thinking about the picture on the bottom...
 As quoted in this 1954 Radio & Television
News magazine article about
analog[ue] computers as compared to digital computers,
"Add two and two. Coming from an analogue computer, the answer would most likely
be, 3.999 or 4.001." While that is a true statement, there is one important feature
that an analog computer had over digital computers of the era: once initially set
up with a transfer function, outputs were nearly instantaneous as the input was
varied over a range of values, whereas a digital computer could take quite a bit
of time to crank through involved mathematical equations. Performing tasks such
as computing aircraft flight paths and other...
 The term "ovonic" - a fairly unfamiliar word
these days - appeared in the May edition of Radio-Electronics, in an article
entitled, "All About Ovonics," just a few months after this news item ran in the
January issue (which I posted last month).
Ovonics is a portmanteau of "Ovshinsky" (from Stanford R. Ovshinsky, the inventor)
and "electronics." Read the "All About Ovonics" article for a deeper dive into the
subject. The big deal, which turned out to be not a big enough deal, was the use
of amorphous (strangely spelled "amphorous") glassy compounds as semiconductors
rather than the standard crystalline silicon structures. Maybe someday an enterprising
genius inventor...
 The proper care and feeding of
vinyl records was - and still is - a big topic amongst audiophiles. As with
so many things, phonographs and platters have experienced a resurgence in popularity
in the couple decades as the world gets nuttier and people crave for a simpler,
saner time - imagined or otherwise. I remember back in the barracks at Robins AFB,
GA, where there was always at least one guy who would have a very extensive (pronounced
"expensive") stereo setup complete with an equipment rack, reel-to-reel tape player,
dual cassette tape deck, super-sensitive AM/FM receiver with a huge tuning knob
on the front, a turntable with a precisely... |
