DAS DEALS Marketplace
Dr. Lee DeForest
Carl Kohler: Thin Air My Foot!
Whilst reading this Carl Kohler technodrama
entitled "Thin
Air My Foot!," I happened upon this word new to me: "din," as in "It was dinned
into me." OK, maybe you already knew that, but surely I should have been aware of
its alternate meaning other than being a loud noise ("the agitated cat made quite
a din."). Fortunately, I am not subject to a household of people who refuse to put
things back in their respective places when through with them, but this tale of
woe tells what might be a familiar scenario to you. To be honest, this could have
been written about me as a boy - before the U.S. Air Force taught me a thing or
two about organization and neatness - since I continually frustrated my father by
leaving his tools (and hardware and lumber and paint) scattered in forgotten places
around the house and yard...
Free General-Purpose Scientific and Engineering Plotting Library w/Smith Chart
Dr. Scott Best, of SiberSci RF
engineering services, sent information about the FREE general purpose
DISLIN scientific
and engineering plotting software library that includes Smith Chart support.
The graphics library was initially created at the Max Planck Institute for Solar
System Research beginning in 1985 by Mr. Helmut Michels. Its continual series
of upgrades is as recent as May 2020. The DISLIN library is available for Unix,
Linux, FreeBSD, Windows, Mac OSX, and MS-DOS systems. It supports a variety of public
domain and commercial compilers for Go, Perl, Python, Java, Ruby, TCL, Julia, FreeBASIC,
Free Pascal, R, C/C++, and Fortran (77, 90, and 95). If you are a software developer,
you probably know that most development platforms are supplied with either no plotting
components or very rudimentary versions of for-purchase products. Many cost hundreds
or even thousands of dollars...
Understanding Super-Modulation
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 - is used to view the RF spectrum across
a wide band. Essentially it is a low budget spectrum analyzer...
DC Motors & Generators
Studies of motors usually begin with the
direct current (DC) type - maybe because most students have already had hands-on
experiences with
DC motors in models (cars, boats, airplanes) and/or electricity experimenter
kits. They are small, cheap, and a simple flashlight battery (the ultimate in safety)
makes them run. An alternating current (AC) motor requires either a direct connection
to the house current or use of a step-down transformer, which still carries with
it a high risk factor. This chapter of the U.S. military's Basic Navy Training Course
(NAVPERS 10622) conforms to the tradition, and follows in the next chapter with
AC motors and generators. While reading through the text, I ran across the unfamiliar
term "kickpipe" and wondered how I could have missed that after so many decades
of working with motors - both DC and AC. I didn't feel quite so dumb after looking
up the definition; after all, I was in the Air Force, not the Navy ;-)
Spectral Domain Simulation Vitally Important When Designing Complex Systems
Ed Troy, owner of Aerospace Consulting, was
kind enough to offer a few of his articles for posting on RF Cafe. With more than
30 years in the electronics communications design field, Ed has a lot of valuable
knowledge to impart to us mortals ;-) This third paper demonstrates why using a
highly capable software simulator for system design work is essential because of
its ability to predict and facilitate mitigation of system-generated problems prior
to building and testing the prototype. Case in point are
spurious spectral components generated by the local oscillator and SSB to PM
conversion created in a frequency doubler circuit. This paper was adapted from an
example circuit provided in Keysight (formerly Agilent) Genesys Spectrasys. Spectrasys
is a spectral domain block diagram simulator that allows the user to construct a
system model and quickly determine the system performance. Whether you are involved...
Mac's Service Shop: Buying and Using a Pocket Calculator
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) and performed basic math with a few simple
trigonometric and logarithmic functions. This edition of Mac's Service Shop, entitled,
"Buying
and Using a Pocket Calculator," has Mac telling sidekick Barney about the Hewlett
Packard's HP-45 calculator. According to the Wikipedia entry, the HP-45 entered
the market in 1973 at a list price of $395 ($2,084 today). That's the price of a
high-end gamer's computer these days. Its features were about equal to my $100 SR-50
a decade later. For the budget minded calculator, he also recommended the Unicom
Model 202SR...
Wired Wireless
As you might know, particularly if you are
a frequent RF Cafe visitor, amateur radio operators (Hams) were prohibited from
broadcasting during the entirety of World War II, ostensibly as a security
measure. The concern was that people might unintentionally (or intentionally) convey
information on troop positions and family names, domestic factory locations and
activities, and the general state of the nation in regards to attitude and finance.
Unlike today, that type of data was not easily gathered even by a dedicated deployment
of internal spies. In the early 1940s, the majority of amateur radio activity was
carried out in the form of Morse code, and operators were understandably concerned
about losing proficiency due to lack of use. In order to mitigate the opportunity
for "fist" atrophy, many Hams set up "wired wireless"
stations between residences and club meeting locations. This particular system was
designed to couple to the local overhead electric power lines, but there were also
private setups with dedicated lines between locations. Then, as now, one of the
biggest hurdles with conducting power-line carrier communications...
The Saga of the Vacuum Tube
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 adopted in an attempt
to report the work done in the years where there is a dearth of readily available
published material...
Calls Home from Auto by Short Wave
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? If
not, it really doesn't matter at this point since there is probably some statute
of limitations that absolves him from prosecution...
Bell Telephone Laboratories Solar Battery
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...
Ponderings on Power Measurements
Joe Cahak, owner of Sunshine Design Engineering
Services, has submitted another fine article for posting here. Joe has many years
of automated RF testing experience to leverage when writing this paper on the basics
of power measurement. Joe has published many articles here on RF Cafe. This
Ponderings on Power Measurements article begins: "A power measurement is a scalar
quantity and is a measure of power detected. These measurements can be made a variety
of ways. Most of us are familiar with the notion that voltage (volts) multiplied
by current (amps) is power (watts) and power multiplied by time is energy. At DC
or low frequencies these power measurements from the current or voltage is relatively
easy and not very complicated. As we get to higher frequencies the typical means
of measuring voltage or current breakdown and are not accurate..."
Fundamentals of Color TV: The NTSC System
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...
A Logic Named Joe
Somebody get Al Gore on the phone - preferably
using Skype. It appears that maybe he did not invent the Internet after all. Sci-fi
writer William F. Jenkins, who went by the pen name "Murray Leinster," wrote
a short story entitled
A Logic
Named Joe, that appeared in March 1946 issue of Astounding Science Fiction.
In the story, an amazingly prescient description of the modern Internet is laid
out. The works is copyrighted so I will not replicate the entire thing here, but
these are a few excerpts that sound a lot like Mr. Leinster was in cahoots with
DARPA during the development*. Before I forget, thanks to RF Cafe visitor Terry
W. for sending the link. My comments look like...
Amateur Radio Crossword Puzzle for June 7
Each week, for the
sake of all avid cruciverbalists amongst us, I create a new
technology-themed
crossword puzzle using only words from my custom-created lexicon 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 Lamarr or the Bikini Atoll, respectively. Enjoy!
Electronics-Themed Comics, 1954 Radio & Television News
Today has been a busy day, so a couple
electronics-themed comics from issues of vintage Radio & Television
News magazines help to relieve the stress a bit. I could never figure out why
these comics were buried deep inside most issues at the ends of article continuations.
These two were on pages 88 and 93. The top one is meant to demonstrate just how
obsessed the public was with the relatively new television phenomenon - just look
at what they chose to ignore on the display TV in order to get a peek at the inside
workings of a television set. The other comic, while clever in its intent, would
never pass editorial muster in today's world because of the great hazard it represents.
Enjoy.
