This summer I attended the TI-2 Space workshop put on by the ARRL and DARA in Dayton, OH. We spent 4 days learning how to make contacts with orbiting satellites like AO-27, AO-51 and the International Space Station, just to name a few. The antenna we used was the dual-band Arrow II Antenna. I've owned one for years and really like it. I wish more people had them, but I think most people think spending $140 for an antenna that can only handle 10W is a bit much.

My aim was to make a cheap alternative to the Arrow that is easy to break down for transport and storage. I really like the idea of using aluminum arrow shafts for elements; they are lightweight, straight, weather resistant, and fairly inexpensive. Another nice feature is the #8-32 threaded insert for broad heads that almost every arrow comes with.

I spent a couple of hours reviewing all the "cheap" and "ugly" yagi designs, as well as others like the "tape measure" and even a new-to-me "backpacker" design. They each have their own advantages and loyal followers.

I finally based my antenna design on one found in the ARRL Handbook from 1999. While not an exact replica, my design is very similar. I had decided to go with the through-boom design like the Arrow, as opposed to side-mounted because it is, in my opinion, cheaper. After buying 6 arrows and a quick trip to Lowe's I had a length of #8-32 all-thread and a piece of 3/4" conduit to use as the boom. I marked a straight line down the center of the boom to give me a point of reference, measured out the spacing holes, made sure I was drilling square and level and got to work. After the 3 holes were drilled, I cut 2.5" lengths of all thread for the director and reflector. Since I was going with the split driven element design of the IDX yagi, I would not need threading for the Driven Element, I'd use machine screws for that. Originally I planned to use nylon 8-32 all-thread to go through the boom for the driven element, and feed each side independently similar to the Tape Measure Yagi, but I couldn't find nylon all-thread, and the longest nylon screws to be found came up an inch too short.

I cut a length of RG-58 cable and soldered on two o-ring connectors to slip over the machine screws before screwing on an arrow.
Lastly I cut each arrow to the appropriate length, which worked out to:
- 19 5/8" for each Reflector arrow
- 18 1/8" for each Driven arrow
- 17 1/8" for each Director arrow
The measurements came from IDX's lengths, subtracting 3/4" (for the boom) and then divided by 2 to give me the necessary length for each arrow.
I used a cutoff wheel and my air compressor to cut the arrows to length instead of a hacksaw. The cutoff wheel leaves a clean cut as opposed to sawing.

After putting my MFJ-269 analyzer on the yagi, I found the lowest SWR to be about 1.4 right around the target frequency of 144.490 MHz. Not too shabby for a first yagi.
For those taking my lead, I found it helpful to feed the yagi as perpendicular to the boom as possible. It is also somewhat important for the O-ring feedline connectors to be on the same side of the boom as the arrow.

Here's a pic of me holding the 2m yagi. It's a bit larger than the commercially made Arrow.

update: I've been asked by more than one person why the split driven element. As you read above, it was semi forced on me by necessity. I needed it to be split for mechanical reasons. the screws going through the boom serve as a match, negating the need for the "hairpin" match from the tape measure yagi or a gamma match. The driven elements being split probably do affect the radiation pattern in the long-field, but perhaps only skew the pattern more in one direction.
(TLDR: it's easier that way and it just works!)

update #2: Hello Hack-A-Day! Yes, you can talk to the space station and many other amateur radio satellites.
update #3: Okay, for those that are interested, I'll be putting together kits if you want. Price to be determined based on what you want/need. You can email me at tommy@neodux.com for more info.

I don't "get" the Kindle anymore. It's been almost 6 month since I got it, almost a dozen books later and I think I'm at the end of the road with this neat little device.
At first, I liked the idea of having free 3G internet available. Then low price point of books made it great for buying books without having to wait for the local bookstore to order them, or worse, paying the retail markup.

A couple months ago, Engadget broke this story which I just saw in the NYTimes: Target will begin selling the Kindle 2 in stores nationwide beginning on Sunday, June 6.

Funny, I was just at my local Target earlier this evening and found a book I've been wanting to read. I had read through the first chapter on my Kindle as a "sample", but never went beyond that. I checked the latest Kindle edition price... $12.99. Target's price for the book? $12.80!
Why would I want to buy the Kindle edition that I can't sell or share?!

To add insult to injury, I checked the same paperback on Amazon: $9.99. Amazon is selling the paperback for less than the electronic version! Now, they're going to sell the Kindle at Target in a matter of days and the electronic version of the book costs even more than the same book in the store!

I think the Kindle's business model is falling apart (and has been). I believe the Kindle is headed for the same fate as the other innovative e-ink device: The OLPC (XO) laptop. Both situations are sad, because each had so much potential. Neither will grow beyond a neat concept without completely reinventing itself (which the OLPC seems to be doing with its tablet).

Amazon has been too slow to act on customer ideas, lacked any sort of customization, and failed to cash in on an exploding community of Kindle owners. ...and I don't blame Apple either. The iPad won't replace the Kindle. (eInk is to easy on the eyes for reading - any who wants glossy ebooks?) Amazon let publishers push prices too high and, at least for me, is what kills the Kindle experience.

update: I emailed my concerns to Amazon and got an email reply very quickly. Here's an excerpt from the email:

The price you pay in the Kindle store is based on a number of factors, including the initial publisher price. Recently, several publishers modified their relationship with Amazon to a business model whereby the publisher, not Amazon, sells the Kindle book. In these cases the price is set by the publisher and you will see "This price was set by the publisher" on the product page.

We're working hard to build a successful digital book store and make every effort to provide you with the best prices possible.

So hopefully they can get their business sorted out with the publishers and get back on track. We'll see.

Most of the students where I teach have time in their computer labs to surf the web or play flash games. The IT department, in order to conserve bandwidth and filter "inappropriate material", need to block most games. Since most games are just mind-numbing wastes of time, most teachers support this. Students looking for games will scour the web searching for game sites that aren't blocked. As soon as one game site is discovered, the URL spreads like wildfire before the site is blocked in the next few days. The cycle repeats itself ad nauseum.

Seeing the problem from both sides, I decided to make an "approved games list" of games that at least feature some academic merit. I understand that games can be beneficial and educational while still being enjoyable. I asked my Computer Science class to find games they enjoy and add them to my games list. They needed to list the educational lessons found within the game and the supporting TEKS on my games list.
The end result has grown into "Mr. Gober's Games". Several students use the site daily and it has received the approval of administration.
Ideally, the next step will be to house the site on the school network to reduce the bandwidth load and increase response speed for the user.

Recently I have added a page to add games, a method to report broken or inappropriate games and a new ratings system. The ratings system was my first successful foray into AJAX. I've attempted AJAX before but came up short. Fortunately jQuery made the effort much easier by abstracting most of the work for me. So, take a look at Mr Gober's Games and have fun - don't forget to vote for your favorites!

I've decided to take the plunge and start working on a project that has been sitting in the back of my head since college. I'm setting out to build a CPU from scratch.

I thought that the Neodux crew might want to follow along as I work on this insane project. But not too insane...I've already figured out how I'm going to do it. I just need to do it now.

Follow along and watch as I walk the thin line between avocation and insanity!

...And I know some of you guys are EEs -- maybe you can give me a hand when something eventually goes wrong...

I figure it's high time I publicly weighed in on this whole ebook wars thing. I was just reading and article over on Wired about the whole pricing dilemma currently plaguing Amazon.
I'll start off by saying that I am a Kindle owner/user, so take that as you will.

I was initially unimpressed with the launch of the iPad. the iPod blew us all away when it was announced, the iPhone blew us all away when it was announced. The iPad will take some getting used to. The screen still isn't e-ink like the most successful ebook readers, but it does have touch screen - something Amazon just realized customers want. It doesn't have the battery life of a Kindle, but it does have brand recognition.

The redeeming value about the Kindle, and I've said this all along, is that it adopts the UNIX mentality: "Do one thing and do it well". The Kindle is perfect for reading books. The great part is you can download the books via Whispernet wherever you happen to be. The iPad kinda offers this, but you have to pay more for the 3G device plus you have to pay for the data plan. (The Kindle data plan is free!) [sure, the basic iPad has wireless, but wifi may not always be available. it's not something I have to think about with the kindle]

Ok, so the iPad will let you surf the web, i'll give you that. Yes, the Kindle is essentially the links browser and Whispernet is slow compared to wifi, but remember, the Kindle is an ebook reader, first and foremost. It does that and it does it well, web is an after thought, the same way that iBooks was an afterthought to the enlarged iPod Touch.

There, I said it. The iPad is a grown up iPod Touch. It can surf the web, it can play apps, it has an ebook reader app - so does my iPhone. It does not have e-ink, long battery life, or instant free access anywhere. Is the iPad a Kindle killer? I think killer is too harsh a word for this situation. Capitalists: Competition is a good thing. The Kindle helped design the iPad, and the iPad will help redesign the Kindle. I'm excited to see what the next revision of the Kindle comes out looking like. I'm almost certain it will feature touch.

The iPad is definitely neat, but I think the Kindle will hold its niche - if Amazon can hold its publishers in place. I believe something definitely underhanded is going on between Mr. Jobs and book publishers, but I'll delve into that soon enough.

update: Well looks like gizmodo beat me to the punch with this article - however I'll expand on it with my thoughts later.