Cool Product Archive - 21

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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CompuTemp 5 Electronic Indoor/Outdoor Thermometer

Vintage CompuTemp 5 Electronic Indoor/Outdoor Thermometer - RF Cafe Cool ProductAfter 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 else. This 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 packaging...

Axiom Test Equipment 2024 Calendar - "Test Equipment Museum"

Axiom Test Equipment 2024 Calendar - "Test Equipment Museum" - RF Cafe Cool ProductContinuing its tradition of creating wall calendars with a test equipment theme, Axiom Test Equipment just announced the availability of their year 2024 "Test 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...

Heathkit IM-104 Solid-State Voltmeter Kit

Vintage Heathkit IM-104 Solid-State Voltmeter Kit - RF Cafe Cool ProductThis vintage Heathkit IM−104 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...

Heathkit HW-5400 HF SSB Transceiver Kit

Vintage Heathkit HW-5400 HF SSB Transceiver Kit - RF Cafe Cool ProductThis 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.

Mini Vacuum Tube Amplifiers

Mini Vacuum Tube Amplifiers - RF Cafe Cool ProductJust 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...

Vintage Audio Electronics by Riddim Restoration

Vintage Audio Electronics by Riddim Restoration - RF Cafe Cool ProductWebsite 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...

Coil64 (Coil32) Inductance Calculator Software

Coil64 (Coil32) Inductance Calculator Software - RF Cafe Cool ProductThere 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...

Axiom 2023 Calendar - "Traveling Through Time"

Axiom Test Equipment 2023 Calendar - "Traveling Through Time" - RF CafeThe 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...

Square D Model 5008 Voltage Tester

Square D / Wigginton "Wiggy" Model 5008 Voltage Tester - RF Cafe Cool ProductSometime 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...

Circuit Calculator App for Android

Circuit Calculator App for Android - RF Cafe Cool ProductRF 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 Circuit Calculator 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..."

Cool Product: 3D-Printed Waveguide & Antennas

SWISSto12 3D-Printed Antenna Matrices - RF Cafe Cool Product3D 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 Swissto12, based in Switzerland. As can be seen in the included images from the Swissto12 website, the surfaces are not perfectly smooth...

Western Electric 300B Vacuum Tube Production

Western Electric 300B Vacuum Tube Production - RF Cafe Cool ProductWhilst 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 300B 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 design...

Error Analysis / Calculation Excel Spreadsheet

Error Analysis / Calculation Excel Spreadsheet (Michael Maguire) - RF CafeThanks 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...

CNES RF Propagation Calculations DLL

CNES RF Propagation Calculations DLL - RF Cafe Cool ProductMany 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 antenna parameters...

SymMos Transfer Function Equation Generator

SymMos Transfer Function Equation Generator - RF Cafe Cool ProductThis 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...

Wall Posters by AR RF/Microwave Instrumentation

Wall Posters by AR RF/Microwave Instrumentation - RF Cafe Cool ProductAs 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...

"RF Toolbox" by Holland Shielding Systems

RF Toolbox by Holland Shielding Systems - RF Cafe Cool ProductWhilst 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 v1.9.6.4, 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...

FM to AM Converter for Vintage Radios

FM to AM Converter for Vintage Radios - RF Cafe Cool ProductRF 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...

AN/MPN-13 & AN/MPN-14 Mobile ATC Radar Systems

AN/MPN-13 & AN/MPN-14 Mobile ATC Radar Systems - RF Cafe Cool ProductAs 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 an 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 to you...

Axiom Test Equipment 2022 "Top Hits" Calendar

Axiom Test Equipment 2022 "Top Hits" Calendar - RF CafeMany 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 Axiom 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...

Vintage Heathkit CR-1 Crystal Receiver Kit

Vintage Heathkit CR-1 Crystal Receiver Kit - RF Cafe Cool ProductThis vintage Heathkit CR-1 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

Vintage Heathkit SA-5010 μMatic Memory Keyer Kit - RF Cafe Cool ProductThis vintage 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 completed units...

Heathkit HD-1481 Remote Coax Switch Kit

Vintage HD-1481 Remote Coax Switch Kit - RF Cafe Cool ProductThis vintage 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...

Heathkit IM-2400 Handheld Frequency Counter Kit

Vintage Heathkit IM-2400 Handheld 512 MHz Frequency Counter Kit - RF Cafe Cool ProductThis vintage Heathkit 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 of $200...

Vintage Heathkit GR-48 AM/FM Table Radio Kit

Vintage Heathkit GR-48 AM/FM Table Radio - RF Cafe Cool ProductVintage Heathkit GR-48 AM/FM Table Radio Kit - RF Cafe Cool ProductThis vintage 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...

Vintage Heathkit DG-140 Two-Station Intercom Kit

Vintage Heathkit DG-140 Two-Station Intercom Kit - RF Cafe Cool ProductOccasionally 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...

Vintage NIB Rhode & Schwarz Test Equipment Found in Attic

Cool Product: Vintage NIB Rhode & Schwarz Test Equipment Found in Attic - RF CafeIt'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...

Cool Product: BridgeCom BCD-144250 Rack Mount VHF Duplexer

Cool Product: BridgeCom BCD-144250 Rack Mount (250 W) VHF Duplexer - RF Cafe 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 BridgeCom 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...

Realistic TRC-409 Portable Citizens Band Radio

Realistic TRC-409 Portable Citizens Band Radio (Radio Shack) - RF CafeIt 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...

Free General-Purpose Scientific and Engineering Plotting Library w/Smith Chart

DISLIN Scientific and Engineering Plotting Library w/Smith Chart - RF Cafe Cool ProductDr. 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...

NI / AWR LabVIEW Free Student Edition

NI / AWR LabVIEW Free Student Edition - RF CafeNI (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 a student....

Cloth Face Mask with Electronics Theme Print

Cloth Face Mask with Electronics Theme Print - RF Cafe Cool ProductAs 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 cloth 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...

NanoVNA Portable Vector Network Analyzer

NanoVNA Portable Vector Network Analyzer - RF Cafe Cool ProductPhil 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...

SimSmith Smith Chart Software

SimSmith Smith Chart Software - RF Cafe Cool ProductRandy 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...

"Madman" Muntz TVs, Cars & Zany Commercials

"Madman" Muntz TVs, Cars & Zany Commercials - RF Cafe Featured ProductRF 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...

Free Microwave & RF eBook Downloads

RF System & Circuits eBook Downloads, by Dr. Michael Steer - RF Cafe Cool ProductDr. 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 ...

DMMCheck Plus Calibrator

DMMCheck Plus Calibrator - RF Cafe Cool ProductFellow 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 ...

AppCAD - As Useful as Ever

AppCAD - As Useful as Ever - RF Cafe Cool ProductWhile 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 ...

Applied Microwave Magazine Articles Archive

Applied Microwave & Wireless Magazine Article Archive - RF CafeThose 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 ...

QuinStar Technology T-Shirt

QuinStar Technology T-Shirt - RF CafeIf you visited the good folks at the QuinStar Technology 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 ...

Microsoft Office Deep Discount - Visio, Word, Excel, Outlook, Access

Microsoft Office Deep Discount - Visio, Word, Excel, Outlook, Access - RF CafeIt 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 ...

Slingshot Flying Pig Accelerometer

Slingshot Flying Pig Accelerometer - RF CafeMy 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 ...

QuickSmith Online Interactive Smith Chart SnP Data Plotter

QuickSmith Online Interactive Smith Chart SnP Data Plotter - RF CafeThere'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 Offers Free RF Magnetics Lab Kits + Filter Design Software

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 ...

Build a Candle Snuffer Using a 555 Timer

Build a Candle Snuffer Using a 555 Timer (Delayed Light Turn-Off) - RF CafeA 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 ...

12/7/2018

The Cryotron Files: How the Inventor of the Microchip Put Himself in the KGB's Sights

The Cryotron Files: How the Inventor of the Microchip Put Himself in the KGB's Sights - RF Cafe

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. "The Cryotron 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 ...

11/20/2018

Mini-Circuits' DIY Vector Network Analyzer Kit

Mini-Circuits' DIY Vector Network Analyzer Kit - RF CafeAn advertisement for Mini-Circuits' DIY Vector 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) ...

11/1/2018

Vintage ARRA Attenuator Advertisement in Microwaves & RF Magazine

Vintage ARRA Attenuator Advertisement in Microwaves & RF MagazineTake 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 ...

10/9/2018

Rohde & Schwarz's Pocket Guide: Key Characteristics of Signal Generators and Modulation Methods

Rohde & Schwarz's Pocket Guide: Key Characteristics of Signal Generators and Modulation Methods - RF CafeRohde & 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 ...

10/8/2018

Surprise 12 Volt Battery Mobile Device Charger

12 Volt Battery Mobile Device Charger (Gary Miller Chrysler/Jeep, Erie, PA) - RF CafeSitting 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 ...

6/18/2018

Rohde & Schwarz Offers Free Charts and Pocket Guides

Rohde & Schwarz Offers Free Charts and Pocket Guides - RF CafeRohde & 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 ...

3/14/2018

MLinkPlanner Microwave Communications Link Planning Software

MLinkPlanner Microwave Communications Link Planning Software - RF CafeMr. 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 earth ...

12/18/2017

Marki Microwave Mixer Spurious Product Calculator App

Marki Microwave Mixer Spurious Product Calculator App - RF CafeHyperlinks 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 ...

12/1/2017

Cool Product: QuickSmith, by Nathan Iyer

QuickSmith, by Nathan Iyer - RF Cafe Cool ProductQuickSmith, 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 ...

8/30/2017

Rigol "RF Basics" Technology Guide

Rigol "RF Basics" Technology Guide - RF Cafe Cool ProductYou 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 ...

8/15/2017

Heathkit Introducing a Full-Featured RF Power Meter

Heathkit Introducing a Full-Featured  RF Power Meter - RF CafeAmateur 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. The next-generation 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." ...

6/26/2017

3D Smith Chart Software is Here!

3D Smith Chart v1.0 Software - RF Cafe Cool ProductDr. 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 ...

5/22/2017

Model Rectifier Corporation Advertisement

Model Rectifier Corporation (MRC) Advertisement - January 1972 American Aircraft Modeler - RF CafeThis 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 ...

4/17/2017

Signetics Fully Encoded, 9046 x N, Random access Write-Only Memory

Signetics Fully Encoded, 9046 x N, Random access Write-Only Memory - RF Cafe Cool ProductRF 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

177,000 Coaxial Connector Adapter Combinations from CoaxSol

177,000 Coaxial Connector Adapter Combinations from CoaxSol - RF CafeHow 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 or ...

7/15/2016

EasyEDA® Online Schematic Capture & PCB Layout

 - RF CafeJust 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 ...

7/7/2016