I thought I’d toss is out to my readers: are there any VHF/UHF activities that you are participating in or would like to? I suspect that there are people who would like to have some new ideas, either because of limitations of their license class or their home situation, which may not favor large antennas. I’m also interested in hearing about any Bay Area groups who may do unusual activities on VHF+ frequencies.

But rather than dwell on this, I thought I’d use my internet soapbox to tell you the story of my current cat, Scrappy.

I don’t know whether Scrappy was feral, or merely homeless, but back in 2004 I was working outside in our backyard when a skinny, bedraggled looking cat nervously edged up to me. He was emaciated to the point that he just looked odd. His face was all drawn and his fur was matted. He meowed at me with a rather plaintive sound. I found him something to eat, but he wouldn’t let me get close. Over the next few days, I got him some proper dried cat food and water, and fed him outside. He returned regularly, and began to look healthier. And prettier. We slowly started to move his food dish inside, although he was still an outdoor cat. After a while he’d spend an hour or two in the house, and would let us pet him. Our neighbors next door also would fed him, and he became a regular feature. Eventually, we named him.

He got his name because likes to fight with other cats. While he was timid with humans, he seemed to like to get in fights with some of the other homeless cats that seemed plentiful in the open space behind our home. One day, he didn’t show up for food. I found him in our garage, clearly in some pain, with his fur all matted and wet, and several fresh bite wounds. It was then that all my patience in trying to get to handle him paid off: I put him in a carrier and took him to the vet. That first trip was scary for me: while he struggled with me when I tried to put him in the carrier, he didn’t scratch or bite. Once he was in, he was simply terrified. He cried and very clearly was hyperventilating.

After his first (but not his last) vet visit, we got him all cleaned up and patched. The vet estimated he was maybe a year old or so. We got him all up on his vaccinations, had him microchipped, and found that he’d been neutered, although whether it was because he had a previous home or because he had been part of a program that caught and released feral cats in our neighborhood, we couldn’t be sure. Over the next few years, he got in a few more fights, eventually causing us to endure a painful week of howling when we finally made him a 100% indoor cat, and, minus some brief escapes where he still managed to find someone to fight with, he’s now a permanent fixture with us.

He’s a great cat. Smart, affectionate, and now that he’s fed and taken care of, rather handsome. He likes to spend time between my wife and me, on the footrest of our recliners, out in the living room where his scratching posts, or looking out the window. We’ve taught him to shake hands. I love him. I only wish he’d last forever.

Okay, that’s the story, now the sermon.

Cats and dogs are here because we humans like them as pets, or at least, because we think we do. Sometimes the reality of being a pet owner doesn’t mesh well with what we expect, and animals end up being abandoned or sent to shelters. The Humane Society says that between six and eight million cats and dogs will enter shelters each year. Of those, about three to four million will be adopted, but by their estimates 2.7 million adoptable animals will be euthanized. That is tragic. The story that started this post seemed monstrous to me, but the fact is that whether these kittens were shot or not, they very likely might have been euthanized, even if they were adoptable. Given the joy that my adopted cat-friend has brought me, I can’t help but be saddened by that.

So, I implore you:

1. First of all, if you choose to adopt a pet, be a good caretaker. Think hard about the commitment you have to make to the animal. If you question your ability to care for your pet long term, then buy a plant instead. Animals are living things, and require care and attention. Educate yourself on what it will take to be a good caretaker, and make an informed decision.
2. Spay or neuter your pets. Please. Really. This is just an extension of being a good caretaker. Spaying and neutring animals helps fight pet overpopulation, which is currently overtaxing shelters nationwide. There are other good reasons to do it, but to me, that will do as a start.
3. Please, don’t de-claw your cats. Lots of people think this is no big deal, but declawing is actually a pretty draconian procedure, basically equivalent to amputating your fingers at the endmost knuckle. It is far better for you to train your cats to use a scratching post and accept the occasional nail trim. Declawing cats is traumatic for them, and often can result in other behavior problems.
4. When you are getting a pet, consider getting a shelter animal. These animals are at the last stop, and are looking for a best friend. The Shelter Pet Project website is a great place to start. Until our animal shelters are empty, doesn’t adopting a pet make sense?

And it took about 24 minutes and 4 meters of PLA filament to print:

The blackish bits on the top are an artifact of the previous user printing something using black filament, which took a while to clear out. The weight of this bracket should be about 12 grams, but I printed this test with 100% infill, and I think other model changes could result in a significant reduction in overall weight (I think all 4 brackets could easily be less than 25 grams, and probably be less than 18 grams). As soon as I test this against the real motors, I’ll be putting the revised model files up for download on Thingiverse. Stay tuned!

But I wasn’t too interested in actually building one. But the gods of Internet surfing sent me back to his website today and I found two new projects of exceeding awesomeness:

The FIBIAC – an electromechanical computer

And the even more amazing, purely mechanical Turbo Encabulator:

As my only “value added” link, Chris makes reference to a book entitled “The Mechanism of Weaving”, which detailed the function of the Jacquard looms that were the predecessors of punch cards and early mechanical computers. His edition was published in 1895, but it turns out you can get an online copy from the Internet Archive. Very neat.

Cheap, Sturdy, 1-Hour Quadcopter

Here is the cool timelapse, ending with a short flight after fifty-one minutes elapsed:

Mark has more details and photos here, as well as some realtime construction video. Andreas originally did it as a friendly wager, but I think there is lots of good material here, not the least of which is just the inspiration of seeing someone build a quadcopter in a reasonably short amount of time, using equipment that isn’t very esoteric. Yes, you need the motors, props, ESC and flight control board, but other than that, it’s basically wood and screws.

Thanks to Mark and Andreas for posting this.

Addendum: Moments after posting this, I noticed this new video by David @ flitetest on constructing a tricopter from scratch:

If you are at all interested in RC stuff, flitetest is highly recommended: lots of cool information, lots of good forums, and even some cool kits.

The Bale Grist Mill is a fully restored, water-powered grist mill that grinds grain. We saw the sign on Saturday, and googled it that night, and decided to return on Sunday and see what the tour was all about. It was great: the miller was there leading tours, and spent about an hour talking about the history of the mill, and then allowing us to view all the intricate mechanisms inside that serve to grind grist (the seeds of either wheat or corn) into flour or meal. For a small donation, you can even cart away some of the resulting flour for yourself. Since I’ve been baking bread a bit, I decided to come away with some bread flour, buckwheat, spelt, and some polenta. I’ll let you know how it turns out.

The most interesting thing to me about the mill was how refined the design is. Our guide said that many of the elements for the mill would have been taken from the design published in The Young Mill-wright and Miller’s Guide, first published in 1795 (and available for download at the link!). Its author was Oliver Evans, who received an early (the third, apparently) U.S. patent for an automatic flour mill. It uses the power of water to move grist and grain around through a series of bucket elevators and conveyors. The mechanisms visible at the Bale mill seem rather antiquated to us today, but if one considers the times, they would have been positively cutting edge. The miller, working by himself (perhaps with some “dusties”, or apprentices), could have processed as much as a ton of grain per day. And since lanterns and the like were not allowed because of the risk of explosion, that was just as long as daylight lasted.

It was a lot of fun. If you are in Napa, consider stopping by (and donating money, they don’t receive any state funds anymore). I had a blast.

But at least for receive there might be an interesting alternative. PA0RDT has developed a simple active antenna which has intrigued me.

Here is DL1DBC’s excellent description.

This article points out something which may not be entirely obvious until one thinks about it: antennas designed for transmission and reception have different goals. A transmitting antenna is designed for efficiency: to send as much of the input power out as radio energy as possible. In this context, short antennas have a very low radiation resistance, so other losses tend to dominate, and you lose a lot of power as heat. But receive antennas aren’t concerned with efficiency: you really just want to preserve the signal to noise ratio of the incoming signal. As long as the noise generated by the preamplifier is low, it doesn’t actually matter how efficient the antenna is. A short antenna picks up less of the desired signal, but also picks up less of the surrounding noise. So, these antennas can work reasonably well, especially on frequencies where full sized antennas are impractical such as VLF.

PA0RDT has created a simple preamp circuit, including a way to power the preamp through coax so you can easily mount this antenna remotely, say 50 feet from your house, and avoid the electrical noise that dominates many active antenna setups. A very neat solution, and inexpensive.

Some more links: Scott built one, using the more ubiquitous MPF102 and 2N3904 transistors, instead of the recommended but harder to find J310 and 2N5109 transistors.

Peter Marx got an official one that was built by it’s creator, Roelef Bakker:

You can read about Peter’s experience here.

A neat little project. Roelef’s articles (esp. the second one) linked from DL1DBC’s give lots of details. Worth looking at, particularly if you are interested in VLF/HF/shortwave listening.

His work is accessible from strandbeest.com. I find his creations amazingly cool.

And others do as well, even hamsters (although cats seem less impressed):

But while I’ve found these things fascinating, I didn’t spend a lot of time researching the exact mechanism, nor thought about fabricating my own. And now I don’t need to!

Check out this awesome link to get code to design variants, visualize them, and even OpenSCAD source code go generate actual 3d printed models. That’s just too cool.

Pretty neat!

If you are interested, you can check out the Long Wave Club of America website to learn more about Part 15 operation. If any of my readers have any other up-to-date or interesting LF/MF part 15 links, I’d love to see them added to the comments.

In the recent SolderSmoke Podcast #152, Bill, N2CQR recently took a tiny step into that overlap himself. He got himself Arduino, probably the most popular microcontroller platform, and used it to send out Morse, and then control an inexpensive DDS module to serve as a cool little VFO, complete with a rotary encoder to tune and a little LCD module to give the readout. Check it out:

Pretty darned cool. And both economical and useful. Bill was pretty sheepish about this tiny step into the digital world. In the past, he has expressed a greater comfort with radio circuits that are built from discrete components, such as diode mixers constructed with trifilar coils rather than the NE602 integrated circuits. After building radios with just a handful of discrete transistors, using even the simplest microcontroller which has tens of thousands (if not more) can seem like crass extravagance.

But I think he should cut himself some slack. Actually, not just cut himself some slack, but revel in the new direction his hobby has taken him.

In the strictest sense, QRP radio is just any communication which takes place with less than 5 watts of radiated power. But in the broader, more ideological sense, it means constructing radios which are simple, inexpensive and well optimized, without a surplus of useless features of whistles. There is a certain economy of design. When you look at VK3YE’s design for his “Beach 40″ DSB rig, you have to marvel at the coolness of the design. Only 8 transistors, nicely documented in his videos. He draws the entire schematic out from memory while on the beach.

If your aesthetic finds this kind of circuit pleasing, the idea of injecting a microcontroller into the mix may seem like drawing telephone wires in the background of the Mona Lisa. But I’d submit that you can find aesthetic uses for microcontrollers in radios, even while being able to appreciate these great discrete, analog designs.

First of all, microcontrollers enable new and useful features. Even the simplest microcontroller can be used to send automated signals for things like QRSS beacons. Hans Summers super low power QRSS beacon can send a nice “shark fin” signal using only three transistors, but if you want to send your callsign, it rapidly becomes more difficult. Sure, you could strap a laptop or desktop computer to generate the modulating signal, but that seems very unaesthetic: hundreds of dollars and tens of watts of compute power just to drive a $5 transmitter with only a few milliwatts of output power? He actually sells a little preprogrammed microcontroller that will do the work, or you could get a K1EL keyer chip, but you are injecting a black box in your design, without any understanding or modifiability. But you could open that box up yourself. For the price of a pizza, you can get a dev board that will hook up to your laptop for programming, pull a few milliwatts of power, and dutifully key your transmitter. Once you get familiar with that kind of work, you can then make an embedded controller using just the raw chips: for instance, I have a few of these Atmel ATTINY85s that I got for $1.15 each (about the same as a 555 timer from our local Radio Shack) lying around for such applications. Add a crystal and two caps (or maybe even do away with the crystal, and use its internal oscillator) and your beacon becomes more flexible and more useful. Want to change the message? Have it send the current temperature or battery voltage as well? Piece of cake.

Second, microcontrollers are the easiest step into understanding computers. When I got my first computer back in 1980, it was already pretty difficult to understand the innermost workings of computers, although I did fairly master most aspects of my Atari 400. With modern desktops or laptops, it seems basically impossible. They have dozens of subsystems, with all sorts of interface and operating systems complexity. But these microcontrollers don’t have any operating systems, and because they are mostly self-contained, the total amount of stuff you have to learn is relatively limited. You tell the microcontroller to flip a voltage from low to high, and it does it, without drivers or intermediate layers. It allows the same kind visceral understanding and exploration that QRP is meant to stimulate.

Thirdly, just like the QRP community, it allows you to participate in a robust, vibrant community of experimenters. The people who are experimenting with Arduinos are kindred spirits to the homebrew radio enthusiasts. They want to take simple, cheap building blocks, and through the power of their understanding construct new, useful and novel applications. Even when their area of interests may differ from ours, you can learn from their skills and draw inspiration from their enthusiasm. And we might even find some potential hams in their ranks.

Don’t feel bad Bill: embrace your new digital skills. The more you goof around, the more applications you’ll find, and the more empowered you’ll be. Computers and QRP can co-exist, and even enhance each other.

A lot of it can be constructed with just Dollar tree foam and packing tape. But i recently got access to a 3D printer, and I thought it might be cool to fabricate some parts using that. A good candidate was the motor mount: we wanted the motor to be firmly held, with the appropriate 5 degrees of down angle. I just recently started teaching myself how to design simple parts using OpenSCAD. It bills itself as the “Programmer’s Solid 3D Cad Modeller”, and I couldn’t agree more: it plays right into my skillset. I’ve made an printed a few objects, and for these kind of purely functional 3D objects, I found it to be easy and straightforward.

The basic idea is to make a little plastic bracket that can be mounted at the end of a piece of 5/8″ square wood which is held with mounting tape inside the main fuselage. It took me about twenty minutes to design, and it went through a couple of minor tweaks before it got to it’s final form. And here it is, mounted in my student’s plane:

Mark H. thought it might be of interest to others in the builder/RC community, so I placed it up on thingiverse. Feel free to download it and print it, and let me know of you find it of value.

Motor Mount for the Axon

If all goes as well, we’ll have our first maiden flight of our resulting aircraft, and video and pictures coming soon.

I find a lot of editorializing about amateur radio to be, well, curiously off the mark. For instance try checking out Dan, KB6NU’s well meaning article about why you should upgrade to a General. I mean, that’s what the title is: Why you should upgrade to a General. The reason I find this article so astounding is that despite the title, Dan doesn’t actually provide any reasons why you should upgrade to a General. The entire article presumes that whatever reasons you think you have for not upgrading, they aren’t valid. I find that a tiny bit presumptuous. But what’s really odd to me, is that there certainly are reasons to upgrade, he just didn’t bother to tell you any.

The most important difference (which underlies most of the others) is that you have access to spectrum which is unavailable to Technician class licensees. While Technician class licensees have all you can eat privileges above 50Mhz, they are pretty lean on the HF bands. With a General, you get full access to big hunks (but not all) of the spectrum below 6m, and this opens up a bunch of possibilities for communication. From SSB to RTTY to digital modes, you can participate more fully in the broad range of HF activity. The General exam is not a particularly difficult test, and you get a big bang for the buck. I’ve enjoyed WSPR, JT65 and beacon activity. And of course building and QRP operation. And just a lot of shortwave listening too (hey, no license required!)

But perhaps you don’t want to do any of that. Perhaps EMCOMM on VHF+ is your thing. Or maybe you like mountain-topping with 2m SSB. Or microwaves. Or APRS. Or D-Star. Or satellites. Or ATV. Or meteor scatter. Or EME. Or just hiking with an HT, or keeping in touch while on the road. I’m frankly okay with that, and I wish more hams were less concerned about what other people were doing, and simply got on with doing more of what they like in ham radio. Then, we wouldn’t have to scold and cajole people into upgrading: they would either be interested, or not. With the wide variety of interesting activity accessible to hams with Technician class licenses, it does not strain my credulity to think that it might be enough for someone.

When someone asks you why you don’t have your General or Extra class license, ask them how many moonbounce contacts they’ve made. If it is zero, urge them to upgrade their skills.

Pixar gave a nod to Harryhausen by naming a restaurant (curiously a sushi restaurant) after him in our 2001 film, Monsters, Inc. I doubt that there is anyone in the animation or visual effects industry who wouldn’t name Harryhausen as inspiration for what they do. So long Ray, and thanks for the films.

The truth is, I haven’t done a lot with the Propeller board. I must admit that a lot of it is simply inertia: if something you already know fairly well serves your needs, then learning something new is often a distraction from your task at hand. But there are things about the Propeller that I do find interesting and compelling.

It’s fast. The chip can be clocked up to 80Mhz, and has 8 cogs, each a 32 bit core with 2KB of local storage for instructions and data.

It has a built in byte code interpreter for SPIN, a high level language. Each cog can execute about 80,000 of these high level byte codes per second, or about 640,000 max if all cogs are funning. I have mixed feelings about Spin, but it’s a cool idea nonetheless.

It avoids interrupts, preferring to use cogs to process events. Interrupt processing is challenging for new programmers (and in some cases, even experienced ones) and the cog model might be easier and more flexible for many real time tasks.

It avoids dedicated hardware peripherals, instead providing “virtual” peripherals as software. Because the chip is fast, and there are many cogs, it’s possible to implement many devices such as UARTS, PWM, servo drivers and even video as code which runs on a particular cog in parallel with the user program. This gives the programmer a great deal of flexibility. SPIN supports a library of user-contributed objects which can really lend to the flexibility of the Propeller.

So, there is lots to like! So, for the second year in a row, I’ve shuffled off to meet some of my friends from tymkrs.com at the Official Propeller Conference. It’s a fairly small get together of Propeller enthusiasts, hosted by Parallax and featuring short presentations on Propeller hardware and software techniques. I had a lot of fun. Parallax is a remarkably small company, run by Ken and Chip Gracey, and having maybe forty employees. Besides the Propeller, they manufacture a bunch of other items, including sensors and robotics items. The highlight of the day was a talk by Chip about the upcoming Propeller 2. Chip’s talk was remarkably informative, and so devoid of normal marketing bull that I actually blinked several times at his honesty.

Propeller 2 looks very cool. To me, the most exciting thing is that it one ups the flexibility of the Prop 1 in allowing any pin to be configured as digital or analog, and an input or output. The Prop 1 has been used by hams to directly generate beacon signals but the new capabilities would seem to open a variety of demodulation as well as modulation techniques. Chip said that the first actual silicon for the Prop 2 will be arriving at Parallax this Monday, and that he’ll let us know via the Parallax forums how that goes. I’ll be paying attention.

I had a great time, culminating with a BBQ dinner with Atdiy, Whisker, Roy, Joe, and some of the Parallax crew. It’s inspired me to actually dig in and start learning Spin. I’m staring over at my Parallax board, happily blinking LEDS. It’s a start.

More details on the Propeller as I goof around.

Over on the Open Emitter blog (sorry, don’t know whose blog this is) there is a twist on this basic idea: instead of using a separate oscillator, use the oscillator that drives the microcontroller as the emitter (probably of just a few microwatts into a short wire antenna). To on-off key the oscillator, the Atmel chip is put into power-down mode, and woken up via the watch dog timer. I think it’s a cool idea, and worthy of experimentation. I’ve got some ATTINY85 chips on sale (just $1.10 each) which will probably be breadboarded into a test circuit, using either some of my 10.140Mhz crystals or maybe some of the 80m or 20m crystals that I have lying around.

Check out the article:

Tiny Beacon