Quadrature modulation and demodulation is as
commonplace and unremarkable today as were Space Shuttle launches before NASA cancelled
the program in 2011 (eliminating America's ability to send astronauts into space).
However, before integrated circuit implementation was available, it was a relatively
rarely employed scheme. Yes, there were many applications using analog quadrature
systems, but use with digital communications requires closely matched (amplitude
and phase) pairs of mixers and power splitters / combiners, along with close tracking
over time and temperature. The "magic" of quadrature systems is...
In today's lingo this project might
be considered a cross between the Steampunk and the Maker realms. It is more than
just a desktop conversation piece - although it would be a very fitting fixture
- in that the "Milliwatter" Morse code transceiver is fully functional, portable
(with it's steam engine power source) radio. All the parts needed to build your
own model - miniature working steam engine, DC generator (aka a Dc motor), code
keyer, and electronic components - are still available. It appears you can build
a bare-bones version for under $100, or go all out with vintage-looking components
for about $300-$400. If you undertake this project, I'll be glad to post a photo
of your masterpiece here...
"Eventually," Dr. Herwald said, "we believe
it will even be possible to automatically and continuously produce actual electronic
equipment, such as radio receivers and amplifiers, starting from a pool of molten
semiconductor materials." That was in early 1960 in an Electronics World
article titled, "Molecular Electronics." The term "molecular" references what eventually
became integrated circuits (IC), the first of which was realized in 1958 by Texas
Instruments engineer Jack Kilby. Kilby's IC incorporated one transistor, one
capacitor, and three resistors on a germanium substrate. Building on that success,
researchers envisioned single-chip semiconductors which contained hundreds, thousands,
and even millions of transistors, diodes...
Allegory is not an often seen style of prose
in the electronics writing world, and typically is not meant to be humorous; however,
there have been a few instances of it in the vintage electronics magazines I read.
One of the most famous examples of allegory is a story by Paul Bunyan titled "Pilgrim's
Progress." "She Wore a Red Germanium," by Leta Foster Ide, is a more contemporary
form of allegory that RF Cafe visitors will appreciate. Mike R. Fonic (microphonic)
is the lead character in the story who complains to his doctor, "I'm off my
feed. Got no capacity. Fact is, I'm in a breakdown." Mike's wife's Aunt
Enna (antenna) is no help, evidently. Come to think of it, the author's name,
Leta Foster Ide...
Popular Electronics magazine printed in April 1966 its
first notice of
new frequency units to be used beginning with the June edition.
The May issue included this piece titled, "Comes the Revolution - or - '40 Million
Frenchmen Can't Be Wrong'." Predictably, not everyone liked it. With the
June issue came the promised change and along with it the first in a series of reader
responses. I also found a reader's opinion from the August issue as well. Evidently,
not everyone wanted to honor Heinrich Hertz by naming the base unit of frequency
in his honor...
Any time I see an article that references
causing limb movements by poking the brain with electrical signals, I think of the
old The Far Side comic. Artist Gary Larson drew quite a few hilarious operating
room scenarios.
Electrocution is of course not a laughing matter - unless it happens
to someone else and it is not serious and no harm is done. Then - and only then
- can it be funny. I've laughed at myself many times after receiving a good
jolt due to stupidity. Sometimes after such an experience I wonder how I never killed
myself from getting zapped as the result of being too lazy to turn off a circuit
breaker before servicing a light switch or receptacle. The sad thing is that I'll
probably do it again some day...
I suppose a more appropriate title for this
chart would be "Foreign Valve Substitution Data," considering that most (if not
all) of Europeans refer(red) to vacuum tubes as "valves." As with having posted
scores of Radio Service Data Sheet pages for the benefit of hobbyists who restore
and service vintage radio equipment, I also post other hard-to-find reference resources
when I find them. Sure, the number of people looking for this information is extremely
small, but they are extremely grateful for this when in the throes of finding replacement
tubes (valves). Posting a hyperlink to this page on the RF Cafe homepage will assure
that...
Author Howard Wright takes the opportunity
here to distill the
concept of modulation down to its basic operation while dispensing
with the garbled mix of "graphs, formulas, charts, vectors, diagrams, and Greek
letters which often enter into various discussions of modulation". Wright describes
how to the uninitiated radio dial spinner, the culmination of events occurring behind
the scenes in an AM reception is akin to knowing "that, to be reproduced, the picture
[in a magazine] was broken down into its primary colors, if all we had to go by
was the original print and the magazine?" That is a very apt comparison...
At least 10 clues with an asterisk (*)
in this
technology-themed crossword puzzle are pulled from this past week's
(7/16 - 7/20) "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 list 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...
Television broadcast stations were quickly
growing in number in the post-Korean War era and the FCC needed to devise a scheme
for
accommodating more channels. There were only 13 channels (only
2-13 used) allocated in the VHF spectrum with 6 MHz-wide bands. Even though
VHF propagates primarily in a line-of-sight mode, reflections and earth-bounce can
extend the range fairly significantly, limiting density in closely spaced cities.
The military refused to yield any spectrum so a decision was made to add new channels
(14-83, also 6 MHz wide) in the UHF band. UHF presented its own problems with
more difficult equipment manufacturing issues and higher atmospheric attenuation.
It never really caught on because cable TV was being widely installed in metro areas...
You probably need to be a
Ham radio operator to fully appreciate the humor in some of these
comics. The first one, for instance, is a poke at a guy proudly pointing out his
QSL cards from distant (DX) stations "right near the city limits," "on the other
side of town," etc., basically what you can pull in with a home Citizens Band (CB)
radio base station and a rooftop antenna. In another, the "73" signoff code is from
the Western Union telegraph standard meaning "Best regards." "88" means "Love and
kisses," hence the guy's unnerved response. The others don't really require
an insider viewpoint. Let me know if you need any more help ;-)...
Dr. Linder's patented AC and DC
generators exploited alpha (proton) and beta (electron) particle emissions from
radioisotopes contained within. The device is basically a metallic sphere concentric
to an enclosed mounting platform for polonium (α
particle emitter), phosphorous (β particle emitter), or similar elements. With
just a gram of radioactive material, the charge which accumulates on the outer sphere
generates a very high voltage (~1 MV) driving a low current (~1 mA). Georg
Ohm's work tells us that is equivalent to 1 kW of power - quite a lot for
a fairly compact device. Dr. Linder envisioned multiple
atomic generators combined in series and/or parallel to obtain
the required power. No mention was made of the effective internal resistance, which
would ultimately determine the terminal voltage when connected to a load...
A 720-line HDTV display is made up of 1,280
vertical lines and 720 horizontal lines of pixels, which gives a total of 921,600
pixels. A 1080-line HDTV has 1,920 vertical lines and 1,080 horizontal lines, for
a total of 2,073,600 pixels. In 1969, a 230 vertical line by 230 horizontal line
electroluminescent (EL) flat-screen television display with 52,900
pseudo-pixels was considered a big deal - and it was since it was the starting point
for digital flat-screens of today. Interestingly, while the "pixel" distribution
was square, the actual display retained the standard 4:3 aspect ratio, meaning horizontal
element width was 33% greater than the vertical element. Since each EL element was
addressed individually, there was no ability of a picture element to be shared by
adjacent "pixels," so displaying a circle would result in a very pixelated picture...
At least 10 clues with an asterisk (*)
in this technology-themed crossword puzzle are pulled from this past
week's (6/4 - 6/8) "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...
This is a great
electronics-themed comic from a February 1972 issue of Popular
Electronics. It encompasses the essence of the stereotypical salesman ruse,
especially in that era when people were sure that electronics repair services were
out to rip them off by selling unneeded services and replacement parts. Aspiring
TV technicians who couldn't grasp the technology moved on to working as mechanics
in a garage, poking tiny holes in brake lines to scare owners into paying for complete
braking system rebuilds. I usually like to post multiple comics on each page, but
at the moment only this one is available...