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 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...
 Robert Taylor, along with inventing the
concept of "super-modulation," also coined the new communications term "Intelligence Transmission Efficiency." It refers in part to the
ratio of power in the intended sideband relative to power in the at least partially
suppressed other sideband and carrier. Admittedly, I have not read this material
enough to fully comprehend the concept of super-modulation, but at least based on
the Fig. 1 waveform, there seems to be an element that adds a DC bias to the
detected signal due to a nonsymmetrical (about 0 Vdc) transmitter modulation by
pumping more power into the positive peaks. I'm happy to be corrected by any
knowledgeable reader. For that matter...
 Robert Taylor claims - without contention
from what I can find - to have invented the concept of "super-modulation," whereby the normal "splatter" created by greater
than 100% amplitude modulation (AM) can be mitigated through use of specialized
circuits. As with many paradigm-changing discoveries, much was made of super-modulation
in the late 1940s through early 1950s, and then it pretty much dropped off the charts.
The cause might have been that the sophistication of circuitry needed to keep everything
tuned and tracking properly to prevent harmonic and sideband was deemed not worth
the trouble once frequency modulation (FM) came on the scene. FM quickly gained...
 It would be more than a decade after the
publishing of this article before the first
direct-to-home satellite television broadcasts would be a reality,
so it shows how long plans were being made for such systems. Rural landscapes are
still peppered with the large vestigial C-band (~4 GHz) satellite dishes, many
with faded eyeballs and other clever (and ugly) artwork on them. Before coaxial
cable was strung beyond suburbs, country dwellers who either could not pull in over-the-air
broadcasts from downtown locations or just wanted more viewing options paid dearly
for satellite service. Equipment and installation costs on early systems could run
into the $30k realm. Today's satellite TV systems use...
 At least in the U.S., laws regarding the
recording of telephone conversations seem to be constantly changing
and vary from state to state. Violation penalties - including imprisonment - can
be severe in both cases. Some states require that all parties in the conversation
be apprised of the recording, while others only require that at least one party
(obviously the one doing the recording) be aware of it. As mentioned in this 1954
"Macs Radio Service Shop" story, some areas require that an audible "beep" be sounded
at regular intervals while recording is occurring. With the ubiquitous use of smartphones
featuring built-in recording capabilities, opportunities for recording and being
recorded are constant...
 Here is an advertisement for Electro-Voice
Manufacturing Company
microphones that I scanned from page 101 of my copy of the February
1943 QST magazine. As with many companies during the World War II
era, this one's theme is the service their products are providing to America's
servicemen. Per the ad: If you were receiving radio messages from men in the midst
of earsplitting battle noises, you'd hear crisp speech undistorted by background
sound effects. Electro-Voice Microphones, in military service, are helping to make
it possible. Similar microphones, designed to achieve such results, will be available
for specific commercial applications ... after our wartime job is done...
 Voltage standing wave ratio (VSWR), often
shortened to SWR in radio work, is a measure of how well a load impedance is matched
to a transmission line. It is defined as the ratio of the maximum RF voltage to
the minimum RF voltage along a transmission line when forward and reflected waves
interfere: VSWR = Vmax / Vmin = (1 + |Γ|) / (1 - |Γ|),
where Γ, the reflection coefficient, is the complex ratio of reflected
voltage wave to incident voltage wave. A perfect match has Γ = 0 and VSWR = 1:1.
An open circuit or short circuit has |Γ| = 1 and VSWR is infinite. In practical
RF systems, VSWR is a convenient scalar indication of mismatch, but it does not
by itself show...
 Who says engineers and scientists have no
sense of humor? This is not an April Fools joke or an attempt to punk you into reading
the story. An Internet browser with strict parental control settings enabled might
even prevent this page from even being displayed. In actuality, the term "G-String Transmission Line" was so dubbed by its inventor, Dr. George
Goubau, as a tribute to his own name - both first and last. Out of an abundance
of caution, I reference the Library of Congress' "G-String" entry for the good
doctor and the device's legitimacy. A drawing similar to Fig. 1 in this
1951 issue of Radio-Electronics magazine can be seen on the chalkboard
behind Dr. Goubau in the LoC...
 Usually, when I read about yet another launching
of rockets from Gaza into Israel, what comes to mind is the barrage of
V1 Buzz Bombs and ultimately the V2 rockets that Germany terrorized
London with during World War II. Although overall not very effective individually,
they did cause brief spells of horror for the localized group of people that were
affected through maiming, killing, or property destruction. The difference between
the Nazi's weapons and Hamas' weapons is that the Germans didn't depend
on other terrorist entities to supply them with their weapons of destruction; they
were brilliant people who had evil intentions of world domination. Hugo Gernsback
writes...
 The 20th Century American electronics industry
produced some of the most influential companies in technological history, from the
laboratories that invented the transistor to the factories that put televisions
in every American home. Yet by the end of the century, many of these
iconic names had passed into foreign ownership through a series of acquisitions
driven by globalization, shifting competitive dynamics, and changing corporate strategies.
Finnish, South Korean, French, Dutch, German, Chinese, Japanese, and other international
buyers acquired what had once been pillars of American innovation. Bell Laboratories,
RCA, Zenith, Magnavox, Sylvania, IBM's PC division...
 Sangamo Electric Company was a "heap" big
name in capacitors in the realm in the middle of the last century. The company always
featured an American Indian in its electronics magazine advertisements, and usually
also included some form of "indian-ese" statements as part of the sales pitch. Of
course such marketing schemes would be vehemently raided and those responsible figuratively
"scalped," if you will pardon the gratuitous expressions. As with using names like
the Washington Redskins, the Atlanta Braves, the Chicago Blackhawks, and the Cleveland
Indians to appropriate and celebrate the bravery and might of the named peoples,
Sangamo implied quality, durability, and reliability...
 Phased
vertical stacks of two or more antennas were fairly common in
the television realm - especially once color broadcasts became more dominant in
the 1950s. Up to 3 dB per additional antenna is possible, but due to various
non-ideal physical parameters (summed phase angle, imperfect antenna geometry, etc.),
realized gain is typically in the 2.5 to 2.8 dB range. Higher signal to noise
ratios were needed to guarantee good color separation with the National Television
System Committee (NTSC) and stereo channel audio separation with the advent of Multichannel
Television Sound (MTS). As you might expect, companies appeared claiming to have
invented physics-defying antennas...
 We take a lot for granted these days with
the seemingly unlimited availability of cheap stuff of all kinds - some of it complete
junk and other of it pretty darn good. That goes for electronics components and
complete products and test equipment, tools, automobiles, appliances, and utensils,
clothing, medical equipment - you name it. Something as simple as a
pistol-type soldering gun can be purchased at just about any hardware
or home store, and at a price that when adjusted back to equivalent money in the
1940s would be amazingly cheap even then. For instance a Weller Soldering Gun kit
from Lowes sells for $39.48 today (less when on sale), which would have been $3.44
in 1947
 In its continuing effort to provide RF engineers
the tools needed to perform their jobs, everything RF website has just added an online
S-Parameters
Viewer. Upload your Touchstone files (.s1p, .s2p, .s3p or .s4p) - or a .zip
containing many of them - to instantly visualize S-parameters on an interactive
Smith chart alongside magnitude, phase,
 VSWR and return/insertion loss plots. Compare
multiple parts, temperatures, or production lots side by side, right in your browser.
No software to install and no account required. To the right is an example of a
.s3p diplexer filter file set uploaded as a .zip file.
 Spurious frequency intermodulation products,
often called mixer spurs, are unwanted output frequencies generated by the nonlinear
action of a frequency mixer. In a diode mixer, the same nonlinear diode behavior
that makes frequency conversion possible also generates many additional frequencies
besides the desired conversion product. Mixer spurs matter because they can fall
inside the desired IF, RF output, receiver passband, adjacent channel, image band,
ADC Nyquist zone, or regulatory measurement bandwidth. The practical industry method
for estimating mixer spurs is to use a manufacturer-supplied m x n spur
suppression table which list the suppression, in dBc, of each mRF ± nLO...
 Syzygy is a great word for a Scrabble game.
If you use it on a Triple Word Score (TWS) space where the "Z" sits on a Double
Letter Score (DLS) space, it will net you 105 points. About the only way to do better
is to use all 7 letters on a TWS play, where you earn 50 bonus points added to your
word score (I've done it twice in the last year).
Syzygy is an astronomical term referring to an alignment of three
or more celestial bodies - not necessarily in exact alignment, but within a few
degrees. Astrologers (not to be confused with astronomers) have since their knuckles
no longer dragged on the ground exploited such scenarios to predict various events
both good and bad. That was even before they...
 As with my hundreds of previous
engineering and science-themed crossword puzzles, this one for
May 3, 2020, 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...
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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.
 Farmers must be a lot smarter than we tend to
give them credit for being. These
math and
logic puzzles that appeared in the 1961 Old Farmer's Almanac are not a duffer's task
to complete. Be careful to consider units of measure based on the venues. Puzzle I is
a relatively simple trigonometry problem, although the wording of the problem statement
is very confusing; it took some head scratching to figure out what was meant. Puzzle
III required me to opt for a graphical solution since I could not come up with enough
independent equations for the number of unknowns. If you look at the OFA page scan...
 I wondered while reading this adventure of Mac's
Service Shop whether author John Frye held stock in the Allen Bradley (now Rockwell)
company (you''ll understand why). This might be one of the earliest instances of literary
product placement in a techno-drama. That A-B resistor is part of the "grasshopper" theme
of this saga, which as always is part fiction and part tutorial. Also discussed is the
increasing level of difficulty in servicing modern electronics as the transition from
all point-to-point wiring to use of printed circuit boards progressed. If Mac and Barney
thought PCBs and leaded transistors caused headaches, they would be having brain aneurysms
with today's integrated circuits sporting ultra fine BGA's, some with more than 500 contacts...
 Here is another article from a vintage issue of
Popular Electronics magazine that I am posting for the benefit of Hams who happen
to be searching for information on
Swiss quad antennas. As with most topics, there are many sources on the Worldwide
Web (when's the last time you heard the Internet referred to as the WWW?) covering how
to build and tune Swiss quad antennas, but this one might have just the right slant on
things that the reader is looking for. It probably is not of great interest to most visitors,
but having it appear on the RF Cafe homepage guarantees that Google, Bing, and other
major search engines will pick it up within hours. Thanks for your indulgence...
 Lightning season is upon us once again. The National
Weather Service says June, July, and August, are the most active lightning months in
the U.S., which is probably true in all of the northern hemisphere, and then December,
January, and February in the southern hemisphere. According to the National Safety Council,
the average American has a 1:114,195 chance of being
killed by lightning in a lifetime (which ends abruptly upon being
killed). That's much less than your chance of dying due to cancer (1:7) or being killed
in a car accident (1:102), but is sucks if you're that one in 114,195. Not all lightning
strikes are fatal, but many cause personal and property damage. Mitigating the chance
of being harmed requires taking some simple actions to not expose...
 TGIF, and that means
tech-themed comics from vintage electronics magazines if I happen to have
any. You'll really appreciate the comic on page 96 of the 1965 issue of
Popular Electronics magazine. In a way, the drawing's concept was very
prescient regarding the future of flexible, bendable circuits. A big part of the
electronics world at the time centered around servicing all the newfangled
circuits and test equipment for troubleshooting and aligning them. As is still
true today, technology changed quickly and there was always a newer model
television, radio, tape recorder, stereo system, video recorder, etc. Customer
interactions and repair shop experiences provided plenty of amusing fodder for
magazine articles and comics. I took the liberty of coloring them...
 John T. Frye first created his
high-tech
Carl and Jerry saga series, a duo of teenage
sleuths, in 1954, for the premier issue of Popular Electronics
magazine. More than 100
adventures carried Carl and Jerry from high school through college. Their practical jokes,
crime solving, and mystery investigations incorporated microphones, timers, cameras,
Ham radio, transformers, metal detectors, remote controllers, home brew circuits, photodetectors,
and a host of other gadgets that could be pulled from a stash of parts in Carl's or Jerry's
basement workshop, or borrowed from a friend. In this story, Carl and Jerry, now students
at Parvoo University in Indiana, have an unexpected confrontation with a radio operator
while exploring a campus...
 "Who needs another
color code chart?," you might be asking. Well, as is always the case there are new
people coming into the electronics field all the time and they are looking for resources
just as we were lo those many years ago when we were first smitten by the science. For
that matter, a lot of seasoned electronics professionals and hobbyists decide to take
on the task of refurbishing or repairing vintage equipment and need a quick reference
for interpreting the colored dots and stripes on resistors, capacitors, and inductors,
as well as the colors of transformer lead wires...
 Withwave's
T-Probe is coaxial probe that offers one signal pin on center and several fixed
pitch ground contact with low inductance. This probe provides excellent electrical performance
for applications having test point with adjacent grounds. They have various pitch ranges
of 0.8, 1.5, 2.5 mm from signal to ground contacts and are produced by precision
manufacturing process. The
T-probe
is available for signal probing test in these applications such as RF module signal insertion/output
measurement , high speed digital & high frequency circuit board analysis...
 Nothing has change in the design and application
of
resistive attenuator pads since this article appeared in a 1959 issue of Electronics
World. It could be legitimately reproduced verbatim in the August 2018 issue of
any magazine. When you crank through the equations you will arrive at resistor values
slightly different from those presented here because the author chose the nearest standard
5% tolerance resistor values. For instance the 10 dB, T-type attenuator for 75 Ω
terminations shown in Figure 7 gives series branch resistors of 33 Ω and a parallel
branch resistor value of 51 Ω. The result is an attenuator that does not present
exactly the desired input and output impedances or the exact attenuation value. More
precise values are 39.0 Ω and 52.7...
 A while back ago I posted a write-up on the vintage
Alliance Model U-100 Tenna-Rotor that I installed in the garage attic with a
Channel Master CM5020 VHF / UHF / FM antenna atop it. There are not many television
antenna manufacturers around anymore; their numbers have been decreasing continually
due first to the advent of cable-delivered TV and now with Internet-delivered TV. The
"cord-cutter" movement is helping to give over-the-air television broadcasting a rebirth
due to the outrageous cost of subscription programming. Anyone contemplating installing
a television antenna today has the same concerns as those back in 1959 when this Channel
Master advertisement appeared in Electronics World magazine - gain, directivity,
bandwidth, ruggedness...
 Electric shock, depending on severity, can range
in damage from mere discomfort to body organ damage to instant death. If you have experience
an
electric shock, you know that avoiding another incident is top priority when working
around high voltages. My worse electric shock was either the time when I got hit with
a 3-phase 440 VAC supply on an industrial air compressor motor, or the B+ vacuum
tube plate supply on the air traffic control radar systems I worked on in the USAF. Both
were, thankfully, from finger to finger or finger to forearm (no vital organs in the
current path). I've been zapped a few other times, but nothing severe enough to require
being resuscitated. Neither have I ever witnessed anyone else being shocked to the point
of needing resuscitation. There are probably some gruesome...
 As one born in 1958, it's hard to accept that
1960 news is nearly six decades old. I still find myself thinking of the 1970s and 80s
as just a few years ago. The first integrated semiconductor circuits were still being
developed in corporate and university laboratories in 1960. Fairchild announced a year
after this Electronics World article appeared their first commercial IC series,
named "Micrologic." Until then, an integrated circuit meant something like the compact
module of interconnected ceramic substrates with printed thick film resistors and miniature
discrete components. In other news, Raytheon was ready to deploy their giant ICBM tracking
radar system to deal with the emerging global nuclear war threat...
 Do you have an FM radio in your cellphone? If
so, its antenna is the headphone or ear bud wires. You can buy an external FM antenna
that plus into the headphone jack. Do you remember the type of
line cord antenna described here? It was actually not a bad idea in many situations.
Although the appliance might look a bit scary, there is no direct physical contact between
the antenna wires and the house AC supply. Either a capacitor with low impedance in the
radio and/or television band was connected to the plug blade or a capacitively coupled
plate was placed around the AC wires to pick up signals. 60 (or 50) cycle content on
the antenna would be minimal and rejected by the receiver front end filtering. Many of
the problems people had with this or any twin-lead transmission cable were due...
 In my nearly 60 years of building model aircraft,
cars, boats, and rockets, working on cars, maintaining houses and yards, working with
electrical and electronic apparati[sic], and many other activities, I have inhaled and
had skin contact with
many types of chemicals (all legal, BTW). You probably have, too, if you are near
my age. At least by the 1960s the public was becoming aware of the dangers of exposure
to common household and workplace substances, but viewing older pictures and films showing
people working with no eye, ear, or skin protection explains the all-too-common common
sight of crippled and disfigured people back in the days. In the early and mid 1970s
I worked regularly with MEK until it was removed due to being labeled as a suspected
carcinogen...
 The
stacked halo antenna is a compact configuration for obtaining a nearly omnidirectional
radiation pattern with nearly 8 dB of gain. An ideal half-wave dipole antenna provides
2.15 dB, so adding 5 to 6 more decibels by merely stacking two halo antennas (which
are essentially curved half-waves) might seem like getting more than the sum of the parts.
That extra gain is obtained by concentrating the vertical radiation pattern lower to
the horizon as compared to a straight half-wave, even though the horizontal pattern loses
a bit of gain contribution from the translation to a nearly omnidirectional nature. There
is nowadays a plethora of information available on the Internet regarding stacked halo
antennas, but in 1965, this Popular Electronics article... |
