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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Luis Flores is graciously providing a free Excel spreadsheet for performing mixer spur analysis - The
Distances Chart. I downloaded and ran it, and it looks very nice. Although the author claims it is a new
concept, Collins Radio invented the format many moons ago, and in fact, as far as I can tell, my
software from the early 1990s was the first to implement it in code. I have been considering doing this in
Excel for along time, but thanks to the hard work of Senõr Flores, there is no longer a need. Maybe I'll take
a few extra naps instead.
Star Wars weapons are a step closer to reality thanks to Wicked Laser's new Spyder III Pro Arctic Series. The high intensity blue laser module is actually part of an image projector system - it just happens to resemble a lightsaber (yeah). News reports of the unit quotes the company's website as warning that the 1 W output "...will blind permanently and instantly and set fire quickly to skin and other body parts..." It appears the "set fire quickly" part of the warning had been removed by the time I visited the site for verification. Still, its 445 nm blue light generates a beam that exceeds safe exposure levels by a factor of 75x. That is a wicked laser. For just $200, maybe I could use it to fry the squirrels that are robbing Melanie's bird feeders. Hmmm...
This week's product is a little different than most in that it requires you to construct it yourself. Designer Dan Davies wrote to me about his simple but effective anti-theft device for use in automobiles, snowmobiles, airplanes, etc. It is a device called the "G-Spot" that splices in series with the ignition wire that requires the operator to tough it prior to starting the engine. The security feature is simple - you have to know where it is and that is needs to be touched for enabling. A nicely done video is provided showing to to assemble the device, so the DIYers out there can tackle it without fear.
is an iPhone that is guaranteed to not have an antenna problem. In fact it might just have the cleanest signal
around even though they feature just one bar... of soap, that is. LOL, really, folks, I'll be here all week.
Also available are BlackBerry, Droid, Pre and iPod soap bars with various scents.
Not in the market for iPhone soap? How about a Antenn-Aid for your iPhone 4? "We're getting a new order every
minute," claims the inventor.
If you still have not been able to part with your retro turntable, but all your old vinyl LPs are too worn to play, you might be glad you kept it. A German company called Optimal Media Production has created a technique for making a hybrid disc with a standard CD on one side and pressed vinyl record on the other. Techno DJ Jeff Mills has created a combo version of "The Occurrence" that sells for $35. It is currently sold out - likely from all the publicity like what it is getting here. The guy's a bit weird (UFOs, etc.), but it sometimes takes "out of the box" [of reality] thinking to come up with this kind of an idea.
On a little bit different tack, this week's Cool Product is no product at all. This is worse than the current epidemic of gray market items, in that at least with the gray market, you actually get a functional - albeit illegal manufactured - version of what you need. In the case of the Intel Core i7-920 μP seen here, a lot of effort went into creating an elaborate faux version that looked amazing real... right up to the point it was removed from the box. The contents turned out to be an nicely done picture of the μP / cooling fan and some lead weight. Even the holographic Intel sticker on the box looked authentic.
Charts are all the rage these days. AWR led the way a couple years ago with a contemporary version of the
mixer intermodulation spur graph in their Visual System Simulator software. This white paper on
Planning discusses the use and advantages of the format. Here's how it works. One axis is the input
frequency divided by the LO frequency. The other is output divided by LO. Each line plots a single spur
product, 1x1, 1x2, 2x1, 2x2, 2x3, etc. Then, a box is constructed that represents the frequency boundaries of
the input / output realm. Any spur line that crosses through the box is an inband product. This allows you to
visually determine not just which products lie inband, but also how close surrounding spurs are. Nice.
If there was ever a product designed for the purpose of guaranteeing at least one new candidate for the Darwin Award, this has got to be it. Were it not for the accompanying serious video from the DoD, you might suspect the power harvesting "Bat Hook" was a joke. It is designed to be tossed over an overhead power line so that field operators can gain access to electrical power. With a properly trained user, this device undoubtedly provides a very convenient way to recharge batteries or power emergency equipment. Still, keep an eye on the 2012 award honorees.
This is a slick new product by Narda Microwave-East. Their Model 743-60 step attenuator provides attenuation of 0 - 60 dB in 10-dB steps via a thumbwheel and direct readout. It covers DC to 18 GHz with a deviation of ±1 dB or less from 0 to 40 dB, and no more than ±1.5 dB to 60 dB of attenuation. Resetability is less than 0.05 dB, VSWR is less than 1.5:1, and temperature stability is 0.0001 dB/dB/°C. The attenuator can handle RF input power of 2 W average and 200 W peak. The 743-60 can be panel-mounted.
a sort of electronically incestuous manner, this really cool clock uses analog multimeters to effect an analog
multimeter themed clock.
Alan Parekh designed and built this really slick clock to look like a plus-size Simpson 260 analog
multimeter. It uses three small analog multimeters to display hours, minutes, and seconds. A μcontroller
calculates the current required to position the analog meter needles per the time of day. This is a really
great way to mix old and new technologies - akin to the
nixie tube clocks. Unfortunately, the mini-meters are an offshore brand, which mutes the nostalgic je ne
sais quois just a bit. Maybe make a label to put over the names for yours.
USB ports are used for a lot of things, from powering keyboard lights, communicating with wireless devices (via a dongle), to even the original purpose like interfacing to a wired peripheral. So, why not use the USB port to charge batteries? USBcell batteries have a built-in USB connector and charging circuitry all within the form factor of a AA battery. The NiMH cell is rated for 1.2v at 1300 mAh. Pretty cool indeed.
Here is a unique service that offers produces for sale without charging a fee. There are currently more than 700 items listed. Clients include both private parties and dealer; however, dealers are limited to offering used or new old stock (stuff not currently in production). SecondHandRadio.com has been around for a couple years, and advertises in ARRL's QST magazine. Since there is no middle man fee, prices are the lowest possible for test equipment, electronic components, radio gear, vintage TVs, and more. The website gets its funding from advertising, so as with similar websites (one in particular comes to mind), please be sure to visit those advertisers and support them if possible.