RF Cafe Software
About RF Cafe
1996 - 2022
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...
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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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first saw this being pitched in a model airplane magazine for use as an inexpensive, lightweight tracker in
case the model flies away. If the case if removed, its weight can be as low as 1.25 oz. This TK-102
GPS/GPRS/GSM Personal Tracker by Sunvalleytek integrates a cellphone with a GPS receiver so that when you want
to locate the unit, you simply give it a call, and it responds with its GPS coordinates. It can also be
programmed to send out location data at regular intervals, or if the unit is transported outside a defined
area, if it exceeds a predefined speed, and other parameters. The 850, 900, 1800, and 1900 MHz bands are
available. It uses the proven SirF 3 chipset. I couldn't find info on whether a separate network subscription
is required to use the device. That is a pretty impressive resume for a device that costs less than $100.
Wireless speakers are not exactly new, but MusicLites ads a new twist (pun intended) to the technology. Simply screw a Music Lite into any light socket and you instantly have a high fidelity sound anywhere within a 50-80' range (200' LoS) from the transmitter. To sweeten the deal even more, you still get the equivalent of a 65 W light bulb (software-dimmable LEDs) along with the sound. A 20W amplifier drives MusicLite's 2.75" speaker through the full 50 Hz – 20 kHz audio range. Up to 3 separate transmitters (2.4 GHz ISM band) can address the speakers in up to 5 separate zones. You can broadcast to and control them from any USB port using a transmitter dongle or even from your iPhone. A Tx/MusicLite costs $350, and each additional MusicLite costs $250. Expected lifetime is about 5 years for the light - not sure about the speaker.
Haven't upgraded to the iPad2 yet? It's a good thing you waited. Here is one made just for you. "Encrusted with 12.5 cts of 'IF' flawless diamonds, a magnificent total of 53 individually set sparkling gems dwell beautifully in solid 24 ct Apple logo with rear section formed again in 24 ct gold weighing an immense 2 kg." If that's not enough, there are also bone shavings from a 65 Myr-old T-REX's thigh and crushed, 65-Myr-old Ammolite rock. I guess that's the "History" part of what you're paying for. But wait, there's more: A single cut 8.5 ct flawless diamond inlaid in its own platinum is surrounded with 12 outer flawless diamonds. Noooow how much would you pay? For a mere £5M ($8M), you can pick up one of these Gold History editions compliments of maker-of-expensive-toys-for-the-ultra-rich, Stuart Hughes. If that is a little out of your price range, there are many more devices with accoutrements that will set you apart at the next status meeting or Starbucks rendezvous. (warning: audio plays automatically on website)
were the best of times. They were the worst of times. These seem to be among the worst, but no matter the
condition of the world, there are always those with the means to afford high-end stuff. If it wasn't so, then
there would not be the plethora of big dollar products that perform basically the same as much cheaper
versions for much less money. Don't get me wrong, I'd love to be able to afford something like this MC275 tube
stereo amplifier by the McIntosh company. According to their website, the MC275's "extraordinary Unity Coupled
Circuit" and "lush sound that presents a powerful and detailed soundstage" was originally engineered in 1961.
The 2011 rendition has been highly polished and spiffed up with gold plated connectors and binding post and a
designer look. The 12AT7 and 12AX7 vacuum tubes on the front row cause me to wax nostalgic over my former USAF
ATC radar days. KT88 tubes drive the outputs to 75W. Pick one up today for just $6,500. I graciously accept
gifts, BTW - thanks in advance.
Simply being able to survive a dunking in the john is no longer enough to qualify as a rugged cellphone - at least as far as the Guinness Book of World Records is concerned. It now takes something like the Sonim XP3300 Force™ to make the grade, and in fact it just did. "The Sonim RPS goes far beyond MIL-SPEC ruggedness... Even wastewater 2 meters deep is no challenge for this IP-68 rated, water and dust proof handset, which can also be dropped from 2 meters onto concrete. The 2 inch high-resolution display is protected by a class leading 1.5mm thick Corning® Gorilla® Glass lens for the highest scratch and shock resistance." 2 meters might be the guaranteed drop survival height, but this phone lived through a drop onto concrete from 25 m (82'), or about 8 stories high, to qualify for the Guinness record. I rarely carry a cellphone, but I have a daughter who owns and runs a horse riding academy who beats up phones terribly. She could definitely use one.
Something old, something new, something borrowed, something blue. So goes a familiar saying about making preparations for a wedding. Vin Marshall's très cool Tube Amp iPod Dock is a perfect example of the wedding of the old and the new, with possibly something borrowed, and built from blueprints. Using 3 big honk'n transformers and 8 vacuum tubes (aka valves to the other side of the Pond), an iPod dock, an aluminum (aka aluminium) chassis, and a handful of leaded components, the Tube Amp iPod Dock is another retro accessory for modern technology. The Model 16LS, 16 W stereo tube amp is a commercially available kit that costs $250. It is built on a PCB, so no classic point-to-point wiring is necessary. There are a few wires to solder between the amp and front panel volume control and power switch. Fitting the assembly into a nice wooden case would really be the pièce de résistance! Complete building instructions and plans are available. I'm not sure whether feeding digitized music into a tube amp can restore that unique sound quality that, so swear audiophiles, only tubes can provide.
you trust your cycling well being to a wireless brake systems that "only" works 99.999999999997% of the time
(3 failures in a trillion)? That means if you use your brakes once per minute every minute of your
life, you risk running off a cliff or into a wall once every 1.9 million years. Of course if the
once-in-a-million-lifetimes failure first occurs on the fifth squeeze of the brake handle, you would be out of
luck. However, any non-Darwin-Award candidate would simply squeeze the handle a second time, upon which there
is statistically no chance it would ever fail again while you own the bike.
Saarland University professor
Holger Hermanns, currently chair of
Dependable Systems and Software, who designed and
analyzed the wireless braking system, is using his invention as a platform for investigating similar systems
being developed for planes, trains, and automobiles. Some technical specs are given in the article.
Modularization has been key to widespread application of leading edge technology across nearly sector of consumer (and commercial) products. Look no farther than the plethora of greeting cards that will record and then play back personal message, for a price of less than $10. How about wristwatches for $10? That's the power of modular electronics, especially for highly specialized functions. WiMM Labs has just pushed the frontier a significantly farther with its Platform module. Within its 32×36×12.5 mm cube is a 160x160 pixel, full-color, capacitive touch screen LCD, WiFi and Bluetooth transceivers, an accelerometer, a magnetometer (compass), and a speaker. Its processor and 32 GB of RAM are run by the open-source Google Android™ operating system. A price has not been announced yet, but I'm guessing you won't find one in a greeting card any time soon.
Who would have guessed it? Heathkit just put the "kit" back in Heathkit. Per their homepage, "In late August, Heathkit will debut their new line of Do-it-Yourself kits for common around-the-house items. The first kit will be a Garage Parking Assistant (GPA). The Garage Parking assistant kit lets you build your own system that uses ultrasonic sound waves to locate your car as it enters the garage. The system signals to the driver using LED lights mounted on the wall when the car is detected and in the perfect spot for parking. The GPA-100 kit consists of two primary assemblies - The LED Display in kit form and the pre-assembled ultrasonic range module. The kit will include everything you need to complete the project except a soldering iron and hand tools. Next on the market will be a Wireless Swimming Pool Monitor kit followed by many more. Heathkit wants to continue to bring to its customers interesting, unique Heathkit products. Heathkit is interested in learning what types of products kit builders would like to build. Kit builders can submit their suggestions." A renaissance?
would have thought that you could own a brand-new, dual-channel, 200-MHz, 1 GS/s digital oscilloscope for less
than $1,000? If you have a computer with a USB port, the 2200 series from PicoScope will get you there. Also
included are driver and display software that include spectrum analysis, a multimeter function, and a built-in
arbitrary waveform generator. For less than $270, the 2202 model provides 10 MHz of bandwidth, and a handful
of intermediate models increment up in BW to the ultimate 200 MHz. These o-scopes are small and light enough
to tuck into your laptop computer bag. Since power is provided by the USB port, there is no bulky external
supply to lug along or need to find an AC socket. PicoScope also offers accessories like a 250 MHz, 10x probe
for less than $50, active differential probes, attenuators, and feed-through terminations for equally
reasonable prices. If you are an instructor, a nifty Educational kit is available that includes their 100 MHz
model and components for performing basic electrical experiments and demonstrations - a pretty cool addition.
The RF world has a new hero: Bob Davis, a long-time RF Cafe visitor. Earlier this week, Bob sent me a link to these SMA torque wrenches that can be used to hold SMA connectors from the coaxial cable side. In the last decade, I have had dozens of people write to me looking for such a wrench, and in response, I have spent literally hours searching the Internet, all to no avail. Until this, they simply did not seem to be available. A common home brew solution was to grind out a slot in a standard 5/16" deep socket - it could be messy. Per KCR Products: A full set of coaxial connector sockets for 3.5mm & SMA electrical connectors. The socket fits between connector nuts allowing a technician to properly torque each connector in these limited access areas. The default torque setting for the 3.5mm & 5/16 SMA Wrench for steel connectors is 8 lb-in. SSMA and SMC versions also available. Woo-hoo!
A video of NeoCube showed up on one of the engineering and science websites I visit daily. I'm guessing the "Neo" part of the name stems not from "new" or the guy in The Matrix, but from the niobium used in the super strong rare earth magnets. Per their website, "The NeoCube is an entertainment device like no other in the world. Composed of 216 individual high-energy rare-earth magnets [larger sets available], the NeoCube allows you to create and recreate an outrageous number of shapes and patterns. Your NeoCube will provide you with hours and hours of unequaled entertainment! The NeoCube Alpha is perfect for gaming, expression, stress relief, dual hemispherical brain stimulation and much more. The NeoCube Is literally a puzzle with billions of solutions." You can place a NeoCube on you desk where you used to keep the YBCO superconducting block that, when cooled with liquid nitrogen, would levitate a magnet. I'm guessing both the supply of LiN and the novelty ran out long ago on that one.