Featured Product Archive
The inventions and products featured on these pages were chosen either for their
uniqueness in the RF engineering realm, or are simply awesome (or ridiculous) enough
to warrant an appearance.
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After decades of using various outdoor
thermometers that used a bimetal coil, mercury, or alcohol, I finally decided
after the latest one failed that it was time to get an electronic one. Not
wanting a wireless type that would require batteries, I found a vintage
thermometer on eBay that had a remote alcohol bulb connected to the indoor
display by a thin copper tube. When it arrived, I discovered that the bulb had
burst long ago, and the escaped red dye in the alcohol was evident on the
packaging. At that point I figured maybe an electronic thermometer using remote
thermocouple sensors would be a good option, since being directly wired to the
indoor display unit, no batteries would be required. My first choice for a
vintage electronic thermometer was one of the Heathkit models, preferably
unbuilt, but a pre-built version would be acceptable. After about a week of
keeping a watch out for one, none became available, so I looked for something
CompuTemp 5 electronic thermometer was offered by a few different eBay
sellers. The one I selected appeared to be never used and it had the original
Continuing its tradition of creating wall
calendars with a test equipment theme, Axiom Test Equipment just announced the availability
of their year
Equipment Museum" calendar. In the past, Axiom's calendars juxtaposed an unrelated
topic with various types of test equipment to result in a clever melding of the
two. The 2022 "Top Hits" calendar used historic rock music bands. "Traveling Through
Time," in 2023, references notable historical eras. This "Test Equipment Museum"
calendar presents both a modern piece of test equipment next to a vintage version
of the same type. For example the month of January has both a circa 1948 Associated
Research Hypot Junior 412 instrument and a modern Associated Research 7804 Hypot
model. That represents more than half a century technology evolution by the same
company. Both were/are used to test the ability of electronic assemblies to withstand
high voltage potentials without breaking down. Another example of a company's extensive
history with the same product type is the April page with a 1964 era HP 851A Spectrum
Analyzer and a modern Keysight N9020B Spectrum Analyzer. Axiom really reached back
for the June exhibit by showing a 1920s-30s B-Battery Eliminator RT−40 high voltage
direct current power supply. "B" batteries had a nominal output at 45 volts...
Solid-State Voltmeter kit showed up on eBay. Although I only own a couple
Heathkit items, I have been saving the images of many unbuilt kits in order to
preserve the history. They regularly appear and disappear on eBay all the time -
some models more than others. One of the earliest instances of the IM−104
Solid-State Voltmeter being offered for sale was in the Spring 1976 Heathkit
catalog (p54), at a cost of $94.95 ($504.55 in 2023 money per the BLS) in kit
format, or $149.00 full built and tested. That was/is a lot of cash to lay down
for a multimeter that measures AC/DC voltage and current, and resistance.
However, the alternative if you needed a high input impedance instrument, this
was still cheaper than buying a vacuum tube voltmeter (VTVM), and it is much
smaller, lighter weight, and portable due to being powered by batteries (a D
cell and four AA cells). An article like "The Case for the Transistorized
Multimeter" was evidently deemed necessary in the 1968 issue of Popular
Electronics magazine to convince the VTVM faithful that the newfangled DMM
would make their lives better...
This vintage Heathkit HW−5400 HF SSB
Transceiver kit showed up on eBay. I have been saving the images of these
unbuilt kits in order to preserve the history. The constantly growing list is at
the lower right. The HW−5400 covers the 80− through 10−meter bands as well as
the 10 MHz WWV frequency reference signal and the WARC bands. A video tour is
posted below. A Web search on the Heathkit HW−5400 HF SSB Transceiver shows
mixed reviews. Some people loved it, and others thought it was the worst
transceiver Heathkit ever put out. Of course that's the way it is with most
things. In the case of kits, a lot depends on the skill of the builder, because
even the most proficient operator and assembler of system level parts is not
necessarily a great builder and/or tuner.
Just as vinyl
records have made a comeback in the last decade, so, too, have
vacuum tube amplifiers and
radios. Many vintage vinyl albums from the pre-CD (compact disc) era, as well as
from groups in the 1990s and early 2000s, are being pressed again. In fact,
companies are having a hard time keeping up with demand. Melanie and I have a
respectable collection of original 45 rpm Singles and 33−1/3 rpm LPs records
from groups in the 1960s through early 1980s, that is to say, up through our
tweens and early twenties ... but I digress. With 3.5mm AUX input and 3.5mm
headphone jack output, can be used as a headphone amp and a stereo preamp,
compatible with most audio source such as MP3, iPod, phone, tablet, computer, CD
player etc. and output can connect headphone, amplifier, active speaker etc. to
greatly improve the sound quality. Adopting classic 6N3 vacuum tube to
effectively eliminate the harsh digital sound, providing HiFi clear, soft and
smooth, warm and sweet tube sound. The sound field is wide, especially suitable
for vocals, strings, light music, classical music, etc. Adopting solid state
design, preamp part uses vacuum tube for amplification to make the input audio
signal more natural with high dynamic range, and amp part uses NE5532P op amp to
ensure the speed and power of audio signal transmission...
Website visitor R. Carson Vizina, owner
and chief miracle worker of
Riddim Restoration, recently wrote to inquire
whether I had a resource for repairing or replacing a damaged glass radio dial
bezel for a Packard Bell AM/FM radio he is working on. Unfortunately, I do not
know of anyone who can make a new dial plate, 'thou surely there is someone out
there who does custom silkscreen printing, but the cost would probably be
prohibitive. I suggested that he might try an automotive window repair kit. I
have used the Rain-X method on two windshields and it does an amazing job of
"disappearing" the crack. Use a hair dryer after injecting it onto the surface
facilitates it flowing into the narrowest parts of the crack. Please contact
Carson if you have a suggestion. Zenith Chair Side Record Player Vacuum Tube
Stereo Ventura 65amps Magnavox Portable Record Player After perusing his RiddimRestoration.Rocks website and seeing the amazing audio components he has
restored, I offered to post a description of it on RF Cafe. As the old saying
goes, a picture is worth a thousand words, so rather than me attempt to do
Carson's handiwork justice with a written description, feast your eyes on about
7k worth of words to the right. When asked to provide a short blurb on Riddim
Restoration, he responded thusly...
There seems to be no such thing anymore
as a simple formula for the physical implementation of an electronic component.
Back in the early days of electronics discovery, frequencies were low and the
precision needed for predicting the performance of circuits was equally low. As
techniques for component construction and circuit analysis improved, more
complete formulas were required to have theory match reality. Simple equations
like Wheeler's for a single layer coil was good enough. Now, the more complete
Wheeler model of is often more useful (it is the one that produces the result
shown in the screen shot above). Be sure to conform to proper units.
Fortunately, some kind souls have seen to it that software is available free of
charge that removes the laborious task of typing long equations into a
spreadsheet or into a hand-held calculator. In this case,
Coil64 (or the Coil32,
32-bit version) is available from Valery Kustarev...
The creative juices
were flowing once again at Axiom Test Equipment as evidenced by this year's
(next year's, actually) calendar. Their 2022 calendar had a "Top Hits" theme,
with a clever juxtaposition of various types of test equipment with vintage
(mostly) rock and roll groups. This time the theme is "Traveling
Through Time." Whereas last year had "AC/DC Loads" and "Transient Generator
Orchestra," for 2023 the artists at Axiom Test Equipment take a trip across the
ages beginning in January with the Cretaceous Period where dinosaurs deal with
perilous volcanic ejecta in the form of a spectrum analyzer. Maybe the display
peak is at the cosmic background radiation (CBR) wavelength centered at 150 GHz
(0.2 cm)? February finds cave dwellers exploiting a temperature test chamber for
use with their newly discovered fire. Fast forward to May and you'll see a Load
Bank situated in an Old West town setting. Look closely at the July soda
fountain scene from the 1950's and you'll see amongst the "stars" displayed on
walls and shelves the "Top Hits" calendar (how's that for Madison Avenue-quality
product placement?). The August motif is of course my favorite...
Sometime in the mid 1970's while working
as an electrician, I bought this
Square D /
Wigginton (aka the "Wiggy") Model 5008 Voltage Tester. It was probably considered
high tech in the day. It uses a simple solenoid to drive the indicator needle. The
scale begins at 120 volts and ends at 600 volts on the alternating current (A.C.)
side, and 120 through 400 volts on the direct current (D.C.) side. Surprisingly
little information on the 5008 is available on the Web. Close-up of the business
area of the Square D model 5008 Voltage Tester. Information sheet for the 5008.
Direct current (D.C.) polarity indicator. Example of measuring house voltage with
the Square D model 5008 Voltage Tester. The highest voltage I ever measured with
it was 480 VAC (3-phase), supplying a concrete block forming machine in Annapolis,
Maryland. It was kind of a spooky experience. I'm comfortable around 240 VAC, but
above that level I worry about compromised insulation, especially in damp environments.
Even with the availability of much more sophisticated analog and digital multimeters,
this is still my instrument of choice when working on house circuits. It is still
in very nice condition and gets used on a regular basis - as recently as a couple
days ago when adding a couple circuits to my daughter's horse barn...
RF Cafe visitor Dmitriy recently wrote to
let me know about the extensive suite of electronics circuit design apps he created
for Android smartphones. There is the
app with 170+ circuits for design, 50+ electronics calculators, 20+ application
notes, and a logic solver. The Power Stage Design Tool is for switch mode power
supplies. Filter Designer handles multi-stage analog active filters, and there is
a stand-alone Resistors app. He even has a Cost, Please! app for tracking travel-related
costs. I could be wrong, but it appears most of the capability of the other two
design apps is included in Circuit Calculator. All apps work offline without an
Internet connection. Files sizes are significantly smaller than similar apps. Does
the world need yet another circuit design app when so many already exist, you might
ask? According to Dmitriy: "There is a list of well-known electronics design tools
for Android which can be found in every review for the last 10 years: 'Electrodoc,'
'Every Circuit,' 'Droid Tesla,' 'Electronics Toolbox,' 'RF & Microwave Toolbox,'
and so on. Also, there is a lot of trash on the market that turns finding a good
tool into a quest..."
3D printing of antenna and waveguide components
has been advancing rapidly in the past few years. Early research used plastic that
was then coated with a conductive substance. Once 3D printing using a metallic filament
was developed to the point that the structure could withstand heat cycling, vibration,
and shock associated with aerospace environments, the creation of complex, compound
shapes never deemed possible with traditional machining became reality. Using proprietary
additive manufacturing techniques developed in-house, virtually any form of waveguide
and/or antenna can now be fabricated by companies like
based in Switzerland. As can be seen in the included images from the
Swissto12 website, the surfaces are not perfectly
Whilst doing some research on vacuum tubes,
I ran across the Western Electric website, showing that they are still building
tubes today. In particular, their historic
vacuum tube, available newly manufactured at Western Electric's Rossville Works
plant, for $699 apiece, or $1,499 as a matched pair (they are typically used in
a push-pull configuration). A fair amount of vintage amplifier gear used by musicians
is still in service, and many use the 300B amplifier tube. You might ask why anyone
would spend $700 on a vacuum tube when he could simply buy one on eBay. A search
of recently sold (don't judge by unsold listing prices) 300B tube shows even the
old new stock tubes are selling for $1,500 and up. At those prices, Western Electric
is doing equipment owners a favor by providing brand new tubes using modern materials
and production techniques for about half the cost. You might also wonder why Western
Electric is manufacturing 300B vacuum tubes today. The answer is that they are used
in Western Electric 91E audio amplifiers also being produced, it being the
modern version of their famous predecessor, the WE 91A. "A never before realized
level of performance has been achieved with a completely new approach to SE amplifier
Thanks once again to RF Cafe visitor Michael Maguire
for providing yet another useful spreadsheet†, this one for calculating errors (Error Analysis)
in various sorts of combinations of numbers. It also handily includes an ability
to calculate errors when converting between linear and decibel values - which is
useful when performing cascade analysis. As you might recall from your statistics
and probabilities or error analysis class, errors propagate through a system according
to how serial and parallel elements are combined from input to output. Calculation
can be as simple as linear addition or individual elemental errors to more complex
calculations when multiplication, division, and exponentiation are involved. If
I recall correctly, my introduction to formal error analysis was in a math course
of that name in the Fall semester of my sophomore year of engineering school. It
was a prerequisite to taking Physics II, Chemistry II, and Statistics
and Dynamics classes because laboratory write-ups required that error analysis be
performed on all our projects from that point forward. That was sometime around
1985. The textbook was the one shown in the thumbnail here, and is quite memorable
because of the cover image of a train having broken through the wall of a roundhouse...
Many thanks to RF Cafe visitor Michael M.
for sending me a note about a very handy RF propagation software tool provided free
of charge by the French organization Centre National d'Études Spatiales (CNES, National
Centre for Space Studies). The PROPAGATION
dynamic link library (DLL) contains functions to compute propagation losses
according to ITU−R P.† recommendations. Versions are available for both 32-
and 64-bit Windows and Linux operating systems, as well as for the C and Visual
Basic programming languages. Very conveniently, the DLL functions can be referenced
from within an Excel spreadsheet as well*, and a demo (demoprop.xls - see screen
shot at right) is provided for reference. To access the DLL contents, add the "Propa"
module to your VBA (Visual Basic for Applications) code and call away. A full list
of the functions is given below, including ones for gaseous, cloud and rain attenuation
that factors in temperature, precipitation intensity, and atmospheric noise, as
well as for inputting geographic location (latitude, longitude, and elevation) and
This item from Tarek Mealy showed up on
my LinkedIn feed. He created a nifty software app called "SymMos" that allows you to use
a drag-and-drop interface to create a schematic using MOSFETs, resistors, inductors,
capacitors, bias voltages, and signal sources. Then, click on the appropriate button
to get the transfer function equation for input impedance, gain, transconductance,
or noise figure. SymMos is a work in progress and is available as a free download.
After unzipping the file, you need to change the SymMos.txt file extension to .exe.
Launch the executable and then you'll need to wait many seconds while the program
loads (a black screen is displayed while waiting). BTW, Norton flagged the file
as dangerous since it is new and hasn't seen it before, but I allowed it to run
anyway with no problems. I recreated the example shown in the YouTube video and
it works as advertised...
As of this writing, AR RF/Microwave Instrumentation
is now offering a few wall posters designs at no charge. Among the themes are "RF and EMC Formulas and Charts,"
"Mathematical Tools of the Trade," and "Radiated And Conducted Immunity Test Requirements &
Solutions." Posters by AR RF/Microwave Instrumentation Wall posters used to be a
common sight decorating engineering labs and engineers' and technicians' cubicles,
but since the smartphone boom began, fewer and fewer of them have been made available.
Even with apps for just about every imaginable topic available literally at your
fingertips, sometimes it is handy to look at a large size printed chart for quick
reference. If you would like one of these posters you had better put in your request
now because they could be gone at any time...
Whilst perusing engineering and science
websites for the latest news and reviews, I ran across this "RF Toolbox"
computer software which incorporates a large variety of calculators. As one who
rarely uses a smartphone (I am home most of the time), it is nice to find something
like this meant to be used on a computer and not on a smartphone. Overall, RF Toolbox
is a handy addition to your arsenal of calculators, and I did not discover any calculation
errors while perusing the various screens. A few user interface anomalies were encountered
which should be addressed, as outlined below. Holland Shielding Systems says they
have a periodic update schedule so hopefully some of them will be addressed with
the next release. RF Toolbox v188.8.131.52, as this opening screen shows, has 12
categories of calculators including EMC and shielding (Holland Shielding Systems'
specialty), antennas, radar, filters, mixer spurs, attenuators, and unit conversions...
RF Cafe visitor Bob D. sent me information
on this interesting device that allows owners of vintage
AM radios to receive FM stations
while using the original tuning dial to cover the entire 88-108 MHz band. Monsieur David
Winter, of France, is the designer and seller of this FM Converter for Vintage Radios.
Installation and calibration is not for the faint of heart, since it involves tapping
directly into the circuitry and disconnecting some of the sections where the device
inserts the signal into the audio frequency (AF) section, totally bypassing the
RF and IF sections. A direct connection to the tuning capacitor is used to tune
the module throughout the FM band, which is a primary feature of scheme. However,
it requires the capacitor to be disconnected from all other circuitry to prevent
normal voltages and impedances from adjacent connected components from entering
the integrated circuit (IC). Retaining the AM reception (and possibly shortwave
reception) function requires the installer to devise a custom switching scheme.
It uses the 6.3 VAC vacuum tube (valve) heater supply. In older radios you
need to be sure to locate a "real" ground (common) point to assure the voltage is
properly referenced. The price is €29.90 ($32.83), which is currently the cost of
7-8 gallons of gasoline...
As you might know if you have been visiting
the RF Cafe website for a while, my specialty while in the U.S. Air Force was
Air Traffic Control Radar Repairman (AFSC 303x1). Technical school at Keesler
Air Force Base in Biloxi, Mississippi, included training on the USAF's primary fixed
and mobile radar systems at the time (late 1970s). After graduation, I was assigned
to the 5th Combat Communications Group at Robins AFB, Georgia. There, I worked on
AN/MPN−14 mobile radar system (2 to 3, depending on how many we happened to have
at the time). The AN/MPN−14 was essentially a modified AN/MPN−13 (utility and operations
trailers) with the addition of a large mobile RAPCON trailer. I have attempted over
the years to get hold of the schematics and troubleshooting and alignment technical
orders (TOs), but with no luck. If you happen to have copies of any of them, please
let me know and I will pay to have them mailed to me for scanning, then returned
Many companies (particularly those which
are not publically traded on the stock market and answer to trouble-maker stockholders)
still send "real" Christmas cards to clients. Axiom Test Equipment, a long-time
RF Cafe sponsor, is one of those companies. This year, along with a very nice Christmas
card, the great folks there sent me undoubtedly the coolest custom-designed calendar
I have ever seen - the
Test Equipment 2022 Top Hits Calendar. As you can see in the images below, the
"Top Hits" theme borrowed on some well-known Top 40 type bands whose names
lend themselves to slight alteration for matching with some the gear handled by
Axiom Test Equipment. I particularly like the "AC/DC Loads" meme (AC/DC) for the
January calendar page, and also the December page featuring the Transient Generator
Orchestra (Trans−Siberian Orchestra). A couple of the months' bands are admittedly
not as familiar to me...
Crystal Receiver kit is one the latest unbuilt Heathkit kits which appeared
on eBay, and can still be found there occasionally both in kit form and fully built
sets. I have been saving the images in order to preserve the history. The constantly
growing list is at the lower right. A PDF version of the Heathkit CR-1 Crystal Receiver
Manual can be found here, but I captured the pages (below) in case it disappears
someday. Note the information included on the operation of detectors and oscillators.
The copyright on the manual is 1956, and it appears in the 1958 Heathkit catalog
for $7.95 ($75.10 in 2021 money per the BLS). From the catalog page: "This crystal
radio is just the ticket for construction by young people interested in radio or
electronics - yet it is definitely not a toy. Employs high-quality standard components
throughout. It is even usable as an AM tuner in high fidelity applications. Covering
from 540 to 1600 kc...
Heathkit SA−5010 μMatic Memory
Keyer kit is one the latest unbuilt Heathkit kits which appeared on eBay. I
have been saving the images in order to preserve the history. The constantly growing
list is at the lower right. The first instance I could find for SA−5010 being offered
for sale was in the Christmas 1982 Heathkit catalog, at a cost of $99.95 ($250.40
in 2021 money per the BLS). It went to model number SA−5010A sometime around 1985.
Zenith bought Heathkit in 1979 (and kept the Heathkit name), so that explains whey
their name appears on the errata sheet in the photo. Heathkit SA−5010 μMatic Memory
Keyers can still be found on eBay fairly often, both in unassembled kit form and
Heathkit HD−1481 Remote Coax
Switch kit is one the latest unbuilt Heathkit kits which appeared on eBay.
I have been saving the images in order to preserve the history. The constantly growing
list is at the lower right. The first instance I could find for HD−1481 being offered
for sale was in the Fall 1984 Heathkit catalog, at a cost of $89.95 ($230.61 in
2021 money per the BLS). A comparable remote coaxial switch today is the Ameritron
RCS-4 at $199.95, so the price has remained fairly constant. Use a single feedline
to select from up to four antennas. The Heathkit HD−1481 Remote Coaxial Switch is
a tower or mast-mounted RF coaxial switch that you can conveniently control from
inside your house. the Switch consists of a remote unit - outdoor switching network
- and an indoor control unit...
IM−2400, 512 MHz Handheld Frequency Counter kit is one the latest unbuilt
Heathkit kits which appeared on eBay. I have been saving the images in order to
preserve the history. The constantly growing list is at the lower right. The first
instance I could find for IM−2400 being offered for sale was in the Winter 1981
Heathkit catalog, at a cost of $139.95 ($429.59 in 2021 money per the BLS) as a
kit or $179.95($552.37 in 2021) assembled and tested. A comparable handheld frequency
counter today is the TTi PFM3000 3 GHz Hand-Held Counter, at a cost just south
Heathkit GR−48 AM/FM Table Radio
kit just showed up on eBay, and will be on auction until Monday, April 19th,
2021 (in case you would like to bid). The listing states it is of 1969 vintage,
but the GR−36 shows up in the 1969 Heathkit catalog; the GR−48 first appears in
1970. Photos of the kit are from the current GR−48 listing noted above, and photos
of the fully built kit are from an expired GR−48 listing. In the interest of preserving
the memory of Heathkit's great legacy in the electronics realm, I have been looking
for examples of unbuilt kits on eBay and posting some of the photos here on RF Cafe.
Heathkit products were well known for the completeness of its instruction manuals,
with clearly illustrated instructions. During the writing and editing process, Heathkit
employees were given pre-production kits to take home and build, while annotating
any difficulties or errors encountered. Doing so helped minimize the situation where
the writer inadvertently assumes his own familiarity with the process is shared
by the customer...
Occasionally an unbuilt vintage Heathkit
item appears on eBay with really nice photos of the contents. In fact, I have a
Saved Search that sends me an e-mail whenever one shows up. This morning, a
Heathkit DG−140 Two-Station
Intercom kit appeared on auction. The instruction booklet has a publish date
of 1972, so I looked for a copy of it on the WWW but the only thing I could find
was a PDF for purchase. Despite the 1972 date, it appears it was 1973 when the DG−140
was first available. The 1971 catalog still shows the previous version, the DG−141
(which you might understandably think would be the newer model number). There is
a big difference in the chassis configuration from the DG−141 to the DG−140. Per
the 1973 Heathkit catalog, the DG−140 was priced at $29.95 ($184.91 in 2021 money
- a whopping 6.2x factor in 48 years). Heathkit products were well known for the
completeness of its instruction manuals, with clearly illustrated instructions...
It's not quite as monumental a find as discovering
the Dead Sea Scrolls in a cave, or an original showroom-new Ford Model T sitting
in a barn, but what Martin H. came upon in the attic of a old house in Gorlitz,
Germany, definitely rates an "amazing!" response. Sitting on the Polish border,
previously owned by an east German policeman, the domicile contained one each of
the following pieces of vintage Rhode & Schwarz test equipment in brand new
condition: • R&S Resonance Frequency Meter, Type WAM, BN 4312/2
(ca 1968) • R&S Phase Meter, Type PZN, BN 1941 (ca 1965)
• R&S Power Signal Generator, Type SMLM, BM 4105 (ca 1974). Martin
is looking for a buyer for all three of these magnificently preserved pieces of
electronics history. The photos show no sign of damage, contamination or fading...
For the past few months, this full-page
BridgeCom advertisement has been running in the American Radio Relay League (ARRL)
magazine QST. When I first saw it I though it might be one of those research
laboratory hydraulic apparatuses for generating the kind of pressure found at the
center of the Earth. Scientists use such devices to synthesize diamonds by compacting
coal. In actuality, the four cylinders are part of the
BCD-144250 Rack Mount VHF Duplexer. Per their website: BridgeCom Systems' BCD-144250
Duplexer for amateur and commercial applications. The BCD-144250 utilizes four high-quality
cavities that results in uncompromising duplex isolation. It will handle up to 250W
continuously for the most demanding applications...
It has been a long time since I've had a
citizens band (CB) radio in my car. Back in the 1970s when the
CB craze was at its peak, with songs like C.W. McCall's "Convoy"* topping Casey
Kasem's American Top 40 (AT40) charts, my high school compadres were all installing
23-channel CBs (standard at the time) in their cars and pickups. I joined in with
a Radio Shack unit (don't recall the model number). In those days the FCC required
operators to register and mail a check for a few bucks - same with radio control
(R/C) systems for model airplanes also operating in the same 26-27 MHz radio
band - in return for a "Citizens Radio Station License" document to carry in your
wallet. Most CB channels were spaced at 10 kHz, but the R/C frequencies were
in−between some CB channels spaced at 20 kHz. For instance, my 3-channel OS
Digitron R/C system was at 27.195 MHz, which resided between CB channels 19
(27.185 MHz) and 20 (27.205 MHz). Some electronically savvy CBers would
illegally modify their radios to include operation on those in−between frequencies
(e.g. Ch 19A at 27.195 MHz), thereby creating a scenario where merely keying
up the transmitter could "shoot down" a model airplane if close enough...
Dr. Scott Best, of SiberSci RF
engineering services, sent information about the FREE general purpose
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...
NI (National Instruments) has made their
LabVIEW Student Edition software product available as a free download for students
needing it for school projects. The license is good for 6 months. You can always
download a trial of standard LabVIEW, but it only has a 30-day license. The LabVIEW
Student edition includes most of the same features as the full LabVIEW suite but
adds a watermark on the front panel and block diagram. The download screen requires
some personal information if you do not already have a NI account set up, but that
is not unusual or unreasonable when a company is offering you trials software. I
did the download and was going to set it up and get some screen shots, but after
15 minutes or so it was still installing (and that's on a solid state hard drive,
SSHD), so I killed the process and figured I'd find a video that someone else had
done. If I had a use for the program I would have let it go ahead and complete the
installation, but otherwise I didn't want that much new stuff on my SSHD. Even though
it is called Student Edition, there is no requirement that you prove that you are
As this is written, we in the U.S. are nearing
the end (hopefully) of the virtual house arrest period most of the country has had
imposed upon us by overzealous politicians. Part of the "comeback" plan being bandied
about by governors is requiring subjects/citizens to don
face masks when in public places where the arbitrarily conjured up six-foot
"social distancing" rule cannot be easily maintained. There is no foreseeable end
to this "new normal" imposed upon most of the world. Contrary to what many people
believe, the mask's purpose is not to prevent the wearer from inhaling COVID-19
(aka Wuhan Virus, China Virus - pick your favorite) particles, but to arrest the
body fluids emanating from the wearer's mouth and nose from being spewed into the
air and/or onto surfaces. In response to the shortage of N95 type masks that are
supposed to stop up to 95% of virus particles, many private citizens - mostly women
- worked with health care personnel to design cloth masks that are comfortable to
wear for long periods of time and are reusable by washing them...
Phil Salas, AD5X, published an extensive
review of the NanoVNA vector network analyzer in the May 2020 issue of the ARRL's
QST magazine. Unfortunately, the article is not available to non-members,
but if you are a member or know someone who is, it would be worth reading. He compared
measurements by the NanoVNA with those obtained using an Array Solutions VNAuhf,
which yielded very favorable results. There are many knock-offs of the NanoVNA available,
which is typical since most of these low-cost, high-performance electronics devices
are built using widely available block-level components that make replication relatively
easy. Variations in the quality of coaxial connectors, internal batteries, switches,
etc., can and often does make a big difference in the quality and ruggedness of
the equipment you buy. Firmware and support software can vary significantly as well.
It's a roll of the dice to some extent...
Randy Rogers*, AD7ZU, mentioned in the May
2020 issue of QST magazine the Smith Chart software called "SimSmith,"
by Ward Harriman, AE6TY. SimSmith first appeared around 2011. Being written in Java,
it will run on any operating system that supports Java (Win64, Win32, Apple Mac
OS X, Solaris, and Linux). If you are using Win64 as I am, you will want to download
the "windows64-with-JRE.exe" file. Windows security will try to block it, but it
is safe to run after your antivirus program scans it and gives a green light. AE6TY
recommends using the installation files rather than just downloading the "SimSmith.jar"
file even if you already have a version of Java installed. When launching the program,
the window might not be very large, so grab a corner and stretch it out so the components
are easier to see. After playing around with SimSmith for a while, you might want
to click on the "SimSmith->preferences" menu selection...
RF Cafe visitor Mike M. reminded me
of "Madman Muntz," who
was a widely known television commercial personality on the West Coast from the
1950s through the 1970s. Earl William "Madman" Muntz's zany live and animated commercials
were used highly successfully in selling cars, including one he himself designed
and manufactured called the Muntz Jet. Along with being a master salesman, Madman
Muntz was also a self-taught electronics engineer of sorts. He is credited with
developing the first 4-track stereo tape deck for cars, which was a precursor to
the 8-track tape deck. What Mike mentioned specifically was the line of Muntz television
sets. Not satisfied to merely manufacture TV sets, Muntz created an entire service
shop and fleet of mobile television trucks. It was kind of an early version of the
Nerd Herd. Based on the Madman's trademark method of minimizing the number of components
used in his products...
Dr. Michael Steer, Lampe Distinguished Professor
of Electrical and computer Engineering at the NC State University, has released
half a dozen of his books on RF system and circuit design in the form of OpenAccess
eBooks, and are downloadable at no cost on the NC State website. Dr. Steer
is a prolific author whose books are chock full of highly useful illustrations and
photographs. The first five "Microwave and RF Design" books, volumes 1 through 5, cover a wide
swath of ground with concentrations in radio systems, transmission lines, networks,
modules, and amplifiers and oscillators. The final book, "Fundamentals of Microwave
and RF Design," is a summary of the first five that will prove useful to newcomers
in the field. Excerpts of the books' contents are quoted ...
Fellow amateur radio enthusiast Russ Keller
(KM4RHK), of Wake Forest, North Carolina, has designed and is selling his
DMMCheck Plus test
device for verifying the accuracy of digital multimeters, oscilloscopes, or other
instruments which measure the provided parameters. This compact (2.5" x 2.2"), inexpensive
board is battery powered and can be used to verify the accuracy of seven primary
DMM functions. A very complete description of each function is provided on the DMMCheck Plus
website. A certificate of measured values for each function is provided with the
DMMCheck Plus. Re-measurement, if desired, is free for the first two years ...
While company branding and the user interface
have changed over the years since AppCAD
first appeared on the Hewlett Packard (HP) website, it is still as handy a desktop
tool as ever. The most recent incarnation was provided by Avago Technologies, which
bought Broadcom in 2015 and then adopted its name. You can now download a free copy
of AppCAD from the Broadcom website. Rather than do en extensive write-up about
all the calculation screens in AppCAD, I've posted a sampling of screen shots. Amongst
them are a Smith chart s-parameter plotter, a lumped element balun designer, a microstrip
calculator, a mixer spurious product calculator, and thermal dissipation calculator.
Since according to a popular saying a picture reportedly paints a thousand words ...
Those of us whose were around in the RF industry
in the 1990s and remember a very fine magazine entitled "Applied
Microwave & Wireless." It was published by Noble Publishing Group. The Archive.org
(aka the Wayback Machine, a la from Sherman and Mr. Peabody cartoon) website
has an archive of 410 published articles (as of this writing) on a variety of topics
including antennas, oscillators, filter design and tuning, direct conversion receivers,
microstrip and stripline, RF link calculations, shielding, co-channel interference,
power amplifiers, lightning protection, SAW devices, GPS, dielectric measurement,
circuit and system computer simulation, transistor biasing, RF transformers ...
If you visited the good folks at the
booth at the IMS show in Boston this year (2019), you were probably offered one
of the T-shirts shown here. As you might expect from a company of engineers and
scientists, the design on the T-shirt includes a thinking exercise. Rumor has it
that this is the first question put to interviewees. Can you decode the license
plate message? I asked Ms. Carol Clasby, who probably handed you your T-shirt
at IMS2019 (if you got one), whether someone at QuinStar actually has the license
plate and she responded not yet, but maybe in the near future. I went to the California
Department of Transportation website to see what such a license plate might look
like. It allowed me to reserve the plate, although of course ...
It seems impossible that you can buy
Visio Professional 2019 and Microsoft Office Professional Plus
2019 for less than $10 each, but according to the research I did the offers seems
to be legitimate. Evidently, sellers buy corporate subscriptions and then are licensed
to distribute copies to it agents (we, the buyers). This is nothing new because
I have seen it done for many years. After purchasing a product, you are provided
with a hyperlink for downloading the software directly from the Microsoft.com website,
and also an activation key. Heeding te old saying about if something seems too good
to be true, it probably isn't, I decided to test the system. Back in March, I purchased
one copy each of Visio Professional 2019 and Microsoft Office Professional Plus
2019 for $5.99 and $9.99 ...
My daughter, Sally, in addition to owning
and operating a very successful horse riding school named Equine Kingdom Riding
Academy, has a rather large eBay store she uses as a venue for selling items purchased
at the local Goodwill "Bins" store. She often buys vintage toys with electronics
features - sometimes working and sometimes not. A properly functioning vintage toy,
be it a stuffed animal or a game of some sort, can make a huge difference in the
resale price. When that is the case, she sends them home with me to attempt a repair.
Many times the problem is corroded contacts from leaky batteries. A dental pick
and some isopropyl alcohol usually solves the problem. When that doesn't work, it's
time to open 'er up for a deeper look. Over the years I have found problems ranging ...
There's a new online interactive Smith chart
s-parameter plotter in town, and it goes by the name of
QuickSmith. Justin Coulston, designer of QuickSmith, sent me an
e-mail asking that I take a look at it. I did, and I like what he has done. Assuming
that anybody reading this is already at least somewhat familiar with the Smith chart,
this report will concentrate on the features of QuickSmith. Keep in mind while checking
out QuickSmith for yourself that it is still in Beta phase, so your feedback to
Justin will be appreciated ...
Coilcraft has been around
as long as I can recall since beginning my electronics career in the 1970s. In fact,
Coilcraft was founded in 1945 near Chicago to make custom coils for television sets.
They began manufacturing a line of standard products in the 1970s - no doubt with
supporting my budding career in mind ;-) Inductors and magnetics are their
primary focus. Coilcraft has been an industry leader in surface mount components,
and was one of the first to provide packaging that could be used by pick-and-place
automatic PCB assembly ...
A couple days ago I posted an update on the
Watkins-Johnson databook page that had an unauthorized gag graph titled, "WJ-G1/SMG1
Phase vs. VCTL vs. Frequency vs. Phase of the Moon." When RF Cafe visitor and sometimes
contributor Dr. Marek Klemes* read
that, he sent me a note about remembering this "Delayed
Light Turn-Off" circuit from the Signetics 555/556 Timer Databook. It took a
bit of creative Googling, but he managed to find the datasheet (to the right). The
text was a bit washed out from the original low resolution scan, so I reproduced
the labels (green). This Rube Goldberg-ish contraption works thusly: After a delay
determined by the values selected for R1 and C1, the output
of the NE555 timer goes high and causes resistor RL to heat up enough
to ignite match M1. M1 subsequently lights the fuse on firecracker
FC1, which has tied to its body a string that wraps around a pulley and
holds a rock (which weighs precisely 2π pounds ...
Longtime RF Cafe visitor, electrical engineer, and occasional contributor Alan
Dewey sent me a note yesterday saying a book for which he helped provide a large
amount of research data has been published by authors Iain Dey and Douglas Buck.
Files: How the Inventor of the Microchip Put Himself in the KGB's Sights," is
an extensive delve into the background of Dr. Dudley Allen Buck, whose son,
Douglas, conducted an extensive investigation into his father's mysterious death
that happened to coincide with the death of his colleague and two other scientists
just days after being visited by Soviet computer experts. Dr. Buck was a superconductivity
researcher during his short, highly productive life. A cryotron, BTW, is a superconducting
switch that would make for very low power supercomputers if it could be made practical
in IC form ...
An advertisement for Mini-Circuits' DIY
Network Analyzer Kit appeared in the October issue of Microwaves & RF
magazine. It is evidently the first of a planned series of University Projects.
Billed as an attempt to "Bridge the gap between textbook theory and real-world measurement,"
Project No. 1-UVNA-63 targets college laboratories as low-cost means of procuring
a high performance vector network analyzer (VNA) at a reasonable cost ($2,495.00).
The frequency range is 100 MHz to 6 GHz. Having the student build the
1-UVNA-63 provides a familiarity with a block diagram level understanding of 2-port
VNAs and gives hands-on experience with assembling RF components. Included are filters,
directional couplers, a transceiver PCB (made by Vayyar) ...
Take a look at this
ARRA (Antenna & Radome Research
Associates) attenuator advertisement that appeared in the September 2018 issue of
Microwaves & RF magazine a tell me if it reminds you of something
you might have seen in the 1960's through 1980's. That might not have been the intention,
but seeing it sure triggered my nostalgia mechanism. Even the tag line, "When it
comes to attenuators, nobody - but nobody - can fill our shoes," idiom, being somewhat
dated, conjures up memories of vintage company slogans. Of course the black and
white format feeds the perception. Maybe I'm wrong, but if it appeals to me for
any reason, the ad designers have done their job ...
Rohde & Schwarz has been publishing a
series of good old-fashioned printed (aka hard copy) Pocket Guides on RF test and
measurement topics. This latest one titled, "Key Characteristics of Signal Generators and Modulation Methods: Pocket
Guide," arrived in my mailbox (the physical one at the curb, not Outlook). There
are 116 pages chock full of an amazing amount of descriptions, equations, tables,
and graphs. The main topic areas are analog, vector, and arbitrary (ARB) waveform
generators, and analog and digital modulation methods. It also reviews associated
topics like phase noise, VSWR, intercept points, etc. A sampling of them are reproduced
below. You can get your own free copy by filling out the form on the R&S website ...
Sitting in the waiting room in the local Jeep
dealership, waiting for the technicians to do the annual inspection on the 2011
Patriot, I noticed a 12 volt car battery sitting on a table. At first I assumed
it was just a sales pitch for a new battery, but then I noticed a bunch of small
cables coming from its bottom edge. As you can see in the photo I took of it, those
cables are mobile device charging cords with mating connectors for Apple, USB, and
miniUSB ports. An Internet search did not turn up any of these things, so maybe
Mopar engineers came up with it. Times sure have changed from when ...
Rohde & Schwarz is offering at no cost
a variety of reference charts (posters) for hanging on your lab or office wall,
and some handy-dandy Pocket Guides. In the current age of (seemingly) paperless offices
and laboratories, opening a cardboard package from R&S containing the pictured
items caused me to wax nostalgic over the days when sales reps handed out such materials
during workplace meetings and at trade shows. Wall charts are still fairly easily
obtained, but the spiral-bound pocket guides are more rare. Maybe soon we'll be
seeing the resurrection of cardboard slide rule calculators ...
Mr. Oleg Sakharov, Director of the Center
of Telecom. Technologies, LLC, recently sent me information on the
MLinkPlanner software for performing microwave communications
link design. Judging only from the provided screenshots and the online documentation,
MLinkPlanner looks to be very user friendly and loaded with features. I downloaded
the 7-day free trial and did a quick fictitious link between my house in Erie, PA,
and the WBEN AM radio station in Buffalo, NY. My route is mostly over Lake Erie,
so there was not much in the way of obstructions, other than the curvature of the
Hyperlinks all around the Internet pointing
to Hittite's infamous Mixer Spurious Product Calculator broke suddenly when Analog
Devices swallowed up Hittite in 2014. The good news is that if you still want to
use it, you can find it as the ADI Mixer-Spur Graphical Representation tool on the
ADI website. However, Marki Microwave now has a much nicer
Spur Calculator that you will want to consider. It provides both
a Spur Web format and a Spectrum Analyzer format for presenting mixer spurious products.
The interface is very user friendly both for the input and the output specification.
The Spur Web screen uses a format pioneered ...
QuickSmith, a creation of Nathan Iyer, has
been around for a long time. It is without a doubt one of the most feature-filled
examples of RF design software around. Nathan recently released a Web-based version
of QuickSmith on a GitHub server, which means it works on any platform with a browser
- desktop or mobile. Access is free, and you can save and reload your design files
rather than losing your work once you leave the website. Being online also means
that the latest version is always available. The screenshot to the right illustrates
where to place series and parallel components, and where to access the sweep ...
You might think the world doesn't need another
RF basics book, but the fact is there are so many new people coming into the field
that there is always room for one more - particular a well-done edition like "RF Basics Handbook" from Rigol Technologies. The PDF download
is free, but you do need to fill out a submission form. A replication of the table
of contents give you an idea of all the topics covered. The photos and drawings
are very good quality. Of course the equipment used in the publication are representative
of Rigol's product line, but that's to be expected ...
Amateur radio operators take note: Heathkit,
which in years past was a prime supplier of homebuilt ham radio gear, has just announced
plans to manufacture its first piece of test equipment in three decades. "Now there's
the Heathkit® HM-1002: Intuitive, intelligent, affordable, accurate measurement.
Heathkit® HM-1002 Precision RF Meter™ picks up where
our venerable SWR / wattmeters of yesteryear -- and everyone else's -- stopped.
Incredible new features, yet simple for beginners to assemble and understand. And
you can build and maintain it yourself." ...
Dr. Andrei Muller, progenitor of the
world's first 3D Smith
Chart software program, has teamed with a handful of able colleagues to release
this commercial version of this paradigm-changing design and analysis tool. 3D Smith
Chart enables you to visualize S-parameter data in ways not possible from the Flatland
dweller's perspective that is the traditional 2D Smith chart. Flatland existed
in a plane, and from an observer's perspective a 3-dimensional object entering the
plane from along the Z-axis seemed to appear out of nowhere ...
This back-page advertisement by
Model Rectifier Corporation (aka MRC)
appeared in the January 1972 issue of American Aircraft Modeler magazine.
Note the cool collection of [now] vintage test equipment
shown in support of testing the R/C system. The advertisement shows a rhombic antenna,
the Dana 8015 RF frequency counter, Tektronix 7904 oscilloscope, HP spectrum analyzer,
RF communications synthesizer RF generator, Anritsu precision field strength meter.
I was 13 years old at the time, and anxiously watched for in the mailbox each month ...
RF Cafe visitor Tony C., who is an engineer
working for on of America's great, longtime manufacturers of green farm equipment,
sent me a link to this unique memory IC released by Signetics on April 1, 1973.
Being April 1, 2017, it seems to be an appropriate day to post the Signetics 25120
Fully Encoded, 9046 x N, Random access Write-Only Memory datasheet that per Wikipedia,
"...was created 'as a lark' by Signetics engineer John G 'Jack' Curtis and was inspired
by a fictitious and humorous vacuum tube datasheet from ..."
April 1, 2017
How many times have you dug through a drawer
of coaxial connector adapters
and found what seemed like every possible combination of TNCs, Ns, SMAs, TNCs, UHFs,
SMBs, and <fill in the blank>s except the one
you really need? Sometimes the reason is simply because all on hand are being used
for something else and cannot be 'borrowed' for your use. Other times it is because
the need never existed before. Usually, a quick search on the Internet will turn
up exactly want you want, but for decent a quality adapter you will pay a stiff
price - especially if it is a rare combination of connector types. The truth is,
not often is a combination like QMA-Male-Right-Angle-to-TNC-Female-Bulkhead adapter
Just as the paperless office, predicted to
quickly become a reality when personal computers were beginning to dominate the
workplace and home in the 1980s, has yet to occur, neither has desktop software
for high-end applications totally replaced online equivalents. Microsoft has made
good progress in the last few years in moving part of their Office suite online,
you still need a local copy of Visio, Project, and even their Visual Studio software
development tools if you want to use them. Graphics and video editing software cannot
be used efficiently online. The problem is mostly due to time latency between user
input and software display response. Speed on the host server end is addressable
with pumped up computing power and extra