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 Do you remember your first calculator -
electronic, that is (slide rules and abacuses don't count - actually they do,
right?)? Mine was acquired sometime in the fall of 1976 during my first attempt
at secondary education at Anne Arundel Community College in Maryland, where
eventually, in 1987, I was awarded an Associate's degree in Engineering (which
constituted the first two years of my eventual BSEE at UVM in 1989, on whose
notable alumni list I am not). My name is not in AACC's list of notable alumni,
either. But I digress. My calculator was a Texas Instruments model SR-50 that
had a small red LED display. It cost about $100 ($445 in today's inflated money...
 You genius types might not be able to relate
to the rest of us who read articles like this one entitled "Fundamentals of Color TV: The NTSC System" and are in awe of minds
that conjure such things as the NTSC System and then build, refine, and perfect
working hardware. Making the system backward-compatible with existing black and
white (B&W) signals added to the complexity and cleverness of the solution -
akin but more sophisticated than compatibility of stereo with original mono radio
transmissions. When catchy marketing slogans like the familiar (to old folks) RCA
television advertisement claim of "Before you see the color ... Your ColorTrak System
grabs it, aligns it, defines it, sharpens it, tones it ... and locks the color on
track," what it actually means is that a very smart bunch of engineers and scientists
spent a lot of time and money designing...
 San Francisco Circuits, a leading
printed circuit board fabrication and assembly supplier serving commercial and
defense markets, describes how
Military-grade printed circuit boards (PCBs) are designed for environments
where failure is not an option. Standards like MIL-PRF-31032, MIL-PRF-55110, and
MIL-PRF-50884 define stringent requirements for materials, fabrication, testing,
and traceability, ensuring boards perform reliably in extreme conditions. These
specifications guide engineers and manufacturers in creating PCBs that withstand
temperature extremes, vibration, shock, and humidity far beyond commercial
standards. MIL-PRF-31032 serves as the modern umbrella specification, covering
rigid, flexible...
 Welcome to the
RF Coaxial Connectors
Quiz, an essential module for any engineer or radio hobbyist focused on maintaining
interconnect integrity across their signal chain. Whether you are standardizing
your station hardware, troubleshooting high-frequency signal leakage, or verifying
the physical port interfaces for your test bench equipment, a thorough understanding
of coaxial connector characteristics - from the rugged reliability of the Type N
to the precision of the SMA - is vital. This assessment challenges your proficiency
in connector selection, exploring the differences in mating mechanisms, cutoff frequencies,
constant-impedance geometries, and the practical environmental...
 This could be one of the earliest reports
of
mobile communications between a private automobile and a home
base station. Using a personally designed and installed 5-meter transceiver both
at home and in his car, Mr. Wallace is able to talk to his 12-year-old son
on the way from work. My guess is that in 1935 there were not too many traffic jams,
even in Long Beach, California, so it is doubtful that was the cause for his announced
expected later-than-normal arrival home. The article states the automobile power
supply needed to produce 300 mA of current at 525 V, which is ~160 W
per Ohm's law, which seems unlikely considering car batteries were 6 V
at the time, and that would work out to ~26 A. My question is whether little
Billy possessed a license permitting him to talk back to dear old dad from the home
station...
 Prior to the International Geophysical Year
(aka IGY, which ended up running for a year and a half), spanning from July 1, 1957,
through December 31, 1958, not a lot was known about the upper atmosphere. May 1946,
when this article appeared in Popular Science magazine, was less than a
year after the end of World War II. During the war a lot was learned about
long distance wireless (radio) communications between and across continents and
ship to shore. Scientists theorized about the phenomenon of
charged particles at high altitudes which, being electrically conductive, could
reflect electromagnetic signals so that over the horizon signals could be exchanged.
Coincidence with sunspot activity and aurorae had already been established, but
more knowledge was needed. Rocket...
 This photo of Bell Telephone Labs' three
scientists, G.L. Pearson, D.M. Chapin, and C.S. Fuller, inventors
of the "Bell Solar Battery," reminds me of the very familiar shot of John
Bardeen, Walter Brattain, and William Shockley huddled over their point contact
transistor in December of 1948. The "battery" terminology is an interesting
choice since we normally think of a battery as a charge storage device, but in fact
a battery is fundamentally a charge creation device. A secondary battery may be
recharged by reversing the depleted chemical (or other) process that generated the
initial charge, but it first created the potential via a basic charge separation
process. What we today refer to as a solar cell is a form of primary battery that
is not rechargeable. Just as some chemical batteries (cells) are reactivated by
replenishing the electrolyte, the solar cell is replenished by photons giving up
their energy to the semiconductor substrate...
 Here is the final installation of a 22 part
series entitled "The Saga of the Vacuum Tube," by Gerald Tyne, that appeared in
Radio News magazine in 1946. Part 1 was printed in March 1943. The collective
contents, which covered the development of the vacuum tube from its conception to
the end of World War I, could have been published as a stand-alone book. Author
Gerald F. J. Tyne presented the series to trace the development which
took place up to the end of World War I along a particular branch of the network
of roads which led to the modern radio tube. He traced the evolution from studies
of the interactions between heat and electricity as pursued by the early philosophers
and by the physicists who followed them (Lee de Forest, et al). These limitations
have been...
 There are many online
Fresnel Zone calculators.
Most do the basic calculation for the maximum radius of the Fresnel Zone for a given
frequency and separation between antennas. Some allow you to enter an obstacle's
distance from one of the antennas, and its height, then lets you know if the obstacle
falls within the Fresnel Zone. Very few plot the shape of the Fresnel Zone, and
even less include an obstacle positioned on the plot. Most rare are calculators
which take the curvature of the Earth into account. RF Cafe's new online Fresnel
Zone calculator handles all those parameters. Check it out...
 A few weeks ago I posted a two-part article
on the Taylor
super-modulation principle published in Radio & Television
News magazine in 1948. It was a newly announced technology at the time and
was written by its inventor, Robert Taylor. This piece entitled "Understanding Super-Modulation"
appeared a couple years later by another author, John McCord, where he describes
how it works , how to tune super-modulation circuits, and how it compares to other
modulation methods - all conveniently in "Ham language." Super-modulation is a form
of amplitude modulation (AM) that makes use of carrier and/or sideband suppression
to achieve greater efficiency. A panadaptor - aka pan-adapter, aka panadapter, aka
radio spectrum scope, aka panoramic adapter...
 It has been a long time since I heard this
saying: "Well, they always say that if you want to find out the best and easiest
way of doing something, just put a lazy man at the job." Mac McGregor offered that
line to his service shop technician Barney - in jest of course - when Barney explains
his million dollar invention idea for a
fool-proof vacuum tube tester that can be used by just about anyone.
Mac's Radio Service Shop creator John Frye often used the monthly techno-drama
to introduce some good ideas for new inventions and/or new methods for troubleshooting
problems. Somewhere along the line I think I have seen an advertisement for a tube
tester that used the automation concept dreamed up by Barney...
 I tend to be a traditionalist for most things,
but do not go out of my way to make trouble for other people who don't appreciate
the way things are and have been... as long as, per Thomas Jefferson, "It neither
picks my pocket nor breaks my leg." In other words, if your actions cause me no
financial or physical harm, I'm not likely to oppose your actions - unless they're
illegal. Many older Hams are greatly offended at the FCC for having removed the
Morse code requirement in 2005 for obtaining an amateur radio
operator's license. They see it as a way to separate the wheat from the chaff,
so to speak; that is to say, to maintain a barrier that keeps non-serious aspirants
from gaining entry into the ranks of the elite group...
 For more than a decade, I have been posting
these
Radio Service Data Sheets for radios and various other audio and
visual electronics sets that appeared in vintage electronics magazines. This one
for the Atwater Kent Model 649 all-wave, 9 metal tube, superheterodyne console radio
set was published in the November 1935 issue of Radio Craft. "All-Wave"
radios were popular at the time because they provided access to shortwave bands
so listeners could tune in foreign broadband stations - often with the rudimentary
built-in antenna. Short Wave Listening was actually a worldwide sport that had its
own cadre of enthusiastic participants, including a dedicated magazine entitled
Short Wave Listener...
 We read a lot about the
early
radar system that was in operation at Pearl Harbor in December 1941 when the
surprise attack by Japanese naval airplanes decimated the fleet with a 3-hour-long
raid beginning at around 8:00 on that sleepy Sunday morning. According to "The Untold
Pearl Harbor Radar Story," by C.P. West, the SCR-270B (Signal Corps radio #270,
rev B) radar system had a range of 250 miles at an altitude of 50,000 feet. Westinghouse
built the system in 1940 following a development contract issued by the Army Signal
Corps in 1936. Historical documents report of the three systems on the island, two
had been shut down and that with the remaining system, operators Joseph Lockard
and George Elliot detected a formation of aircraft about 137 miles out to sea. They
were told it was a squadron of B-17s and to not worry about it...
 This news bit from a 1951 issue of Radio-Electronics
magazine reports on the FCC's declaration of illegality the practice by some
FM broadcasting stations of providing a means for
blanking out commercials and station identification to entities
willing to pay for the special receivers and pay for a subscription. Nobody I have
ever known looks forward to enduring commercials on television or radio (or Internet
these days). The only way most of us could listen to music without interruption
was to by a record, tape, or CD. VHS tapes and DVDs provide some relief from commercials,
although even though you pay for them there are typically promotions for other movies
at the beginning. Commercials on radio and television (and now the Internet) have
consumed a larger part of each hour of programming with each passing year. The DVD
collections we have of 1960s and 1970s Prime Time TV shows average run times of
about 54-55 minutes...
 This is another example of a multi-part
article of which I happen to have discovered only one of installments - Part 9.
As is often the case, each article is pretty much stand-alone and does not require
that you have already seen the previous sections. In 1951, computers were still
mostly analog; digital circuits were just beginning to get serious research thanks
to the recent advent of solid state devices. Boolean algebra, truth tables, and
combinational logic were just beginning to be taught in engineering courses.
ENIAC (Electronic Numerical Integrator and Computer), first used
in 1945 at the end of World War II, was the world's first general purpose
digital computer, and its active elements were vacuum tubes - about 20,000 of them.
As you might expect, there was a lot of excitement in the electronics, scientific,
and finance world about digital computers that would be inexpensive enough that
individual corporations...
 Werbel Microwave, who since 2014 has designed and produced high
performance radio frequency components for defense, commercial, test and measurement
applications, is seeking an experienced manufacturers' representative firm to cover
the New England territory (CT, MA, ME, NH, RI, VT). Click thumbnail image for more
detail.
We're looking for a rep firm with:
- Established relationships in defense, aerospace, and commercial electronics
OEMs in the region.
- Complementary, non-competing RF/microwave lines.
- A motivated, technically knowledgeable sales team.
If your firm is the right fit, we'd love to connect. Reach out via DM or email
us at
sales@werbelmicrowave.com
 Moods are sometimes understandably less
than jovial and nerves might be shot after a challenging day at work. These
electronics-themed comics from a couple vintage Radio &
Television News magazines might help assuage your anxieties. The same goes
for those who are in Southern California and managed to arrive safely from a commute
on the notoriously unfriendly highways there. As with many of these old comics,
you have to be privy to the mindset of the day to fully appreciate the topic. TV
repair was big business and people were fascinated with the boob tube innovation
rapidly consuming the attention of domestic dwellers...
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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.
 As with so many topics in electronics, nomenclature
has changed since the time when commercializable solar cells first came on the scene.
Vintage magazines usually referred to them as "solar
batteries," which was really a misnomer since they do not actually store energy
like a battery. In this 1954 edition of Popular Electronics magazine (the
premier issue), solar-to-electricity conversion efficiency rates of 6% are heralded
as wonderful, enough to cause the author to claim "...a wafer-thin slab of crystal,
4 ft. x 15 ft., either resting on or built into the roof of a house, could supply
enough current to operate all the lights, stove, refrigerator, and other appliances
in the house - 24 hours a day." Even with today's efficiencies in the 20-25% realm,
you couldn't power much of a house on a 4x15 foot array. Maybe they meant the number
would be useful if you had gas-powered lights, refrigerator (yes, they exist), and
stove...
 This week's crossword puzzle for November
6th sports a
radar and radio theme. All RF Cafe crossword puzzles are custom made by me,
Kirt Blattenberger, and have only words and clues related to RF, microwave, and
mm-wave engineering, optics, mathematics, chemistry, physics, and other technical
subjects. As always, this crossword contains no names of politicians, mountain ranges,
exotic foods or plants, movie stars, or anything of the sort unless it/he/she is
related to this puzzle's technology theme (e.g., Reginald Denny or the Tunguska
event in Siberia). The technically inclined cruciverbalists amongst us will appreciate
the effort. Enjoy!
 Aside from vacuum tubes occasionally going
bad,
capacitors were undoubtedly the most frequently failing components in television
and radio sets. All electronics of the era (and earlier) of this 1954 issue of Radio &
Television News magazine had chassis full of high voltages and high temperatures
which really strained the integrity of capacitors, especially electrolytic types
used in power supplies and plate circuit decoupling circuits. As if a couple hundred
volts wasn't challenging enough, TV cathode ray tubes (CRTs) often had bias voltages
over 10 kilovolts. Most of us over 60 years old recall at least one instance
of a sizzle followed by a loud pop, followed by the television going dark when a
capacitor failed. It always seemed to happen at the most intense point of a program.
Of course when that kind of failure occurred you knew the set would be out of service
for a while since Dad wouldn't be able to fix it by pulling out all the tubes and
taking to the hardware to test them all on the automated machine. In our very low
income house with five kids, everyone scrambled looking for change in pants pockets
and under sofa cushions to help fund a rapid repair...
 Did you know that the examinations for
Amateur Radio Operator licenses were originally conducted by the Commerce Department,
and not the Federal Communications Commission (FCC)? The FCC was established with
passage of the Communications Act of 1934, which abolished the Federal Radio Commission
(FRC) and replaced it with the FCC. The "Act" combined and organized federal regulation
of telephone, telegraph, and radio communications. That's right, bureaucracies were
renaming and reorganizing themselves even back then in order to expand and increase
control and regulatory power. After all, the more segments of society you command,
the more opportunities there are for accepting graft, payola, bribes, contributions
to political campaigns, etc. But, I digress. When I first wrote this (2016), I was
in the process of studying for the Amateur Extra license and am immersed in review
of electronics principles, regulations, procedures, band plans, etc. Unlike in 1931,
today you can buy a manual that has the entire pool of 700 verbatim exam questions
that are used for the test, so in theory, if you can memorize all potential questions
and answer...
 This
Electronic Crosswords puzzle appeared in the October 1963 edition of Electronics
World magazine. About half the words used are related directly in some way
to electronics or physics. It's a fairly small puzzle so it shouldn't take you too
long to complete. My RF Cafe crosswords, by the way, have 100% of the words directly
related to the sciences, from a custom lexicon I have created over 20 years of making
puzzles. Enjoy...
 Author Maurice Johnson does a pretty
nice job sizing up the
evolution of communications receivers in his multi-part series in Electronics
World magazine. He begins with the pre-World War II radio sets and
works up through contemporary models. A major step in the evolution was going from
simple heterodyne to superheterodyne frequency conversion; that was actually a WWI
innovation. Heterodyne sets usually went from the radio frequency (RF) frequency
directly to audio frequency (AF). Superheterodyne included an intermediate frequency
(IF) prior to final conversion to audio, which permitted a fixed frequency filtering
and amplification stage independent of the received frequency. Also addressed is
the superregenerative circuit which greatly improved signal sensitivity. A shift
from Morse code (digital) to audio communications drove improvement in detector
technology, where the crude coherer type device was of no use...
 Being a big appreciator of good humor, and
especially
technology-related humor, I made sure to scan these tech-themed comics from
the pages of vintage Radio-Electronics magazines. Some of the same themes
from half a century ago are still applicable today - like inventing a device that
will block television commercials (see the page 132 comic). There are a couple huge
differences between then and now, though. For one thing, the percentage of each
hour consumed by commercials has doubled or tripled since 1958. A Prime Time TV
show in 1958 like The Untouchables ran 54 out of 60 minutes (90% show / 10% commercials).
Big Bang Theory, a 2014 show, had a run time of 22 out of 30 minutes (73% show /
36% commercials)...
 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 the form a chain takes when suspended at both ends and
allowed to hang freely in a gravitational field. The hyperbolic cosine function
describes it mathematically. It is also the root of the word "concatenate," meaning
to string together...
 I like the title: "Put
PEP in Your Antenna Tuner." For those not familiar with transmitter lingo, PEP
is Peak Envelope Power, but of course the word "pep," as in energy, is a clever
double entendre. This tuner is for the receive side of operations, so it is not
a high power circuit for blasting out signals for DX'ers to hear on the other side
of the world. If you aren't averse to building a vacuum tube circuit and happen
have a 6AG5 in your parts box, then here's a simple antenna tuner circuit for you.
Otherwise, I'm guessing there are many modern, transistorized tuners you can build
instead. It appeared in a 1958 issue of Popular Electronics magazine...
 Sixty years ago when this "Evolution
in Electronics: Integrated Circuits" article appeared in Electronics World magazine,
commercially manufactured (as opposed to in laboratories and small volume production)
ICs were at the very beginning of their evolutionary lifetime. It was only 14 years
earlier that the transistor's invention first been announced at Bell Labs. Jack
Kilby, of Texas Instruments, is credited with having built the first practical integrated
circuit in 1958. The Darlington transistor IC was a relatively simple achievement
since there were no passive components on the die. A 2-stage amplifier, as shown
in figures 2 and 4, with on-chip resistors and capacitors was a big deal at the
time...
 This installment of Mac's Radio Service
Shop, entitled "A.C.-D.C.
Bread and Butter," could stand alone as a chapter in a troubleshooting manual
for vacuum tube radios. John Frye's (or a trusty consultant's) knowledge of circuit
operation is abundantly clear here. Recall that Mr. Frye later authored the
Carl & Jerry teenage techno-sleuth series in the next decade. A couple
things stood out to me. The first is the heretofore unfamiliar phrase "play hob
with," which means to cause trouble for. The second is mention of a metal tuning
dial indicator needle making contact with a part of the metal faceplate and thereby
affecting the tuning of the radio. What that means is the needle had some level
of voltage on it that could short to the chassis. It was not unusual to have very
high voltages on the dial and button shafts of user-accessible controls, with only
a plastic or phenolic knob or button separating the user from a potentially lethal
shock. Safety grounds were not part of the supply line cord, further increasing
the danger...
 Are you old enough to remember - or have
you ever heard about - the "cat's
eye" on old tube radios that was used for fine tuning of stations? The "eye"
was generated by a special type of electron-ray vacuum tube like this 6E5 from RCA.
A fluorescent disk at the top of the tube was caused to glow in accordance with
the level of control voltage, as shown in figure 2. The electron-ray tube had to
be mounted horizontally in the chassis so that the "eye" was visible from the front
of the chassis. This article from the January 1955 edition of Popular Electronics
magazine also describes how the electron-ray tube can be used as a voltmeter. As
with most things, RCA 6E5 vacuum tubes can be found for sale on eBay. The original
1930's "Coke bottle" variety like the one in figure 3 usually cost a bit more
than the newer versions with the constant diameter glass envelope...
 Author Lon Edwards provided a good introductory
lesson on the subject of
white noise. Since digital communications was not yet a major technology when
the piece appeared in a 1962 issue of Electronics World magazine, pink
noise, a pseudorandom version of the truly random nature of white, was not a concept
well known in the electronics realm. White noise in the audio spectrum is the focus
here, but the general principles apply at all frequencies. Interestingly, he states,
"The word 'white' has been borrowed (inaccurately) from optics and is used to mean
the long-time average energy distribution of the electrical voltages over a specified
frequency spectrum." Solitron Devices (still in business), where Mr. Edwards
was employed, manufactured a noise diode they called the Sounvister SD1-W, a double-diffused,
silicon junction diode. An Internet search did not turn up a single instance of
a surviving Sounvistor...
 Incredibly, author Ray Larson saw this post
and wrote in with a little background on his motivation for the
7031 kHz article!
Back in 2011 when I first posted it, I wrote, "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."
Well, turns out Al is "out there..."
 This schematic and parts list for the
Belmont Model 5P19 vintage radio appeared in a 1947 issue of Radio News magazine.
No functional description or tuning instructions were included. I have scanned and
posted more than 250 of these for the benefit of the many people who restore and
service these vintage radios, and often it can be difficult or impossible to find
schematics and/or tuning information. The Belmont 5P19 is a "suitcase" portable
radio that runs on batteries or house current. Two, 45 volt "B" batteries are
needed to supply 90 volts for the plate bias. A running list of all data sheets
is posted at the page bottom to facilitate a search for other radio models... |
