Putting the "Ek" in "Geek"
The Workbench
USB Digital Setting Circles Kit!
Dec 18th
FAR Circuits has just released a kit for a USB version of my Digital Setting Circles project. The USB version relies on the FTDI TTL-232-5V interface cable as shown in a previous post. A complete writeup is now included on my USB Digital Setting Circles page. Here’s the schematic for this new kit:
USB Digital Setting Circles Schematic
The kit is much simpler than the serial version–the pull-up resistors were eliminated, the oscillator replaced by a crystal, and a MAX232 chip is no longer needed. The board and encoders are powered by the USB port, too, so no external power supply is needed. The kit includes all the components, including the programmed PIC chip, but does not include the TTL-232-5V cable. The cable must be purchased separately and is readily available from Mouser and Digikey, for about $20 plus shipping.
This kit should work great if you want to run your digital setting circles straight through the USB port of your laptop. However, if your goal is to use a bluetooth connection between your computer/PDA/smartphone and the board, then the serial version of the kit is the one you want to use. Furthermore, this USB version really isn’t adaptable for use with a smartphone or PDA–the TTL-232 USB cable needs to plug in to a PC in order to work.
Bluetooth Adapters for My Digital Setting Circles
Jun 19th
I was finally motivated to get my hands on some Bluetooth hardware so I could figure out why my latest ASCOM driver wouldn’t work with Bluetooth. I found mine at U. S. Converters. I needed two–one that would plug into a USB port on my notebook (I bought model BLDONG for $9.99), and one that would plug into the serial connector of my digital setting circles interface (BT232B for $45.00). The BT232B serial Bluetooth adapter also requires a gender changer because it has a female DB9 connector just like my DSC interface, so I bought 10GC-D1 for $7.99, too. I know that AirCable sells this kind of stuff, too, but U. S. Converters seemed a little more economical.
Now it was time to get it all hooked up and functioning.
Field Day: Doing Handsprings Into the Past
Jun 9th
The hams among you know that ARRL Field Day, held the last full weekend in June, is fast approaching. A few of my ham buddies and I usually try to pack up our QRP gear and head into the forest or to the top of a local peak for a weekend of sleeping on the ground and seeing how many contacts we can scare up with just a few watts of power and a wire thrown into a tree. This year I’m trying to get a head start on preparations. I’m planning to take my four-band Elecraft K1 with internal battery pack and run off lithium AA’s for the entire weekend. My antenna’s going to be an old stand-by, a half-size G5RV hung from the highest tree I can find. My K1 has the internal ATU and it’ll tune up the G5RV with no trouble, so I’ll be able to work 40, 20, and 15 meters. I even decided to dust off my old mouse paddle–a computer mouse modified so that the left and right mouse buttons act as the dit and dah paddles (you laugh, but it works great because it’s easily managed with one hand–no need to hold it with the other hand or anchor it to something).
The G5RV Returns
Jul 5th
If you’ve read my past posts here about my antenna projects, you know that I live in a covenant-restricted neighborhood that supposedly doesn’t allow outdoor ham antennas (at least none visible from the street). Thankfully, there is no homeowners association or dues that support covenant enforcement, and none of my neighbors had thus far even mentioned the short vertical antenna I built and installed in my back yard.
Up until now, I hadn’t really given that antenna a good workout. But last weekend was Field Day, and this year I had to settle for working Field Day from the shack. Sadly, I was disappointed by my antenna’s performance. Although I managed to work 50 QSOs in four or five hours, I struggled to hear and contact other stations, even when running 100W. The noise level was very high, and signal levels were underwhelming. I worked only two SSB stations, the rest being CW contacts. It was time to rethink my antenna situation.
Soldering 101
May 8th
For a surprising number of folks, my Digital Setting Circles project is their first introduction to electronics construction techniques–mainly, the art of soldering. If you’ve never seen it done correctly, soldering can be an intimidating prospect. Someone asked me the other day whether there were any YouTube videos of someone constructing my project (none that I know of). That got me thinking–there must be plenty of “how to solder” videos around. So I checked, and sure enough, YouTube has quite a few of them.
Doin’ the Lindy
Feb 15th
The parasitic Lindenblad, that is. I wrote in a previous post about how I was gathering the parts to build the parasitic Lindenblad antenna for 70 cm that appeared in an article in the February 2010 QST magazine. Since then, I’ve actually managed to build one of these beasts, and for what it’s worth, it even looks like the one in the picture in the article. My first trial with it on a good pass of AO-51 was less than impressive, though. For this trial, I used my Kenwood TH-F6A connected directly to the antenna with a three-foot section of RG-8X coax (to minimize the effect of feedline losses, which can be appreciable at 70 cm). There were moments when I had good copy on the satellite, but they were few and far between. I was a little disappointed, but I wasn’t ready to give up yet. Knowing that the antenna, being more-or-less omnidirectional, didn’t have much gain (especially compared the the handheld Arrow Antenna yagi I’d been using), I wondered if a preamp might be necessary.
As if “Parasitic Lindenblad” Isn’t Funny Enough
Jan 30th
A few weeks ago I posted about a new Chinese ham radio satellite, and mentioned a couple of satellite antennas I was considering building. Just a few days later I found the latest QST magazine in my mailbox, complete with an article about (you guessed it) another ham radio satellite antenna project! This one, by AA2TX, describes an antenna he calls a parasitic Lindenblad (here’s a link to an AMSAT article). The antenna, for 70 cm, is right-hand-circularly polarized with an omnidirectional radiation pattern. This makes it well-suited to amateur satellite applications. I liked this design better than some of the others I was considering, so I decided to give it a whirl.
New Ride, New Radio?
Jan 10th
When shopping for a new car, a ham isn’t thinking about performance, color, or gas mileage. Instead, he’s asking himself, “Where can I put the ham radio?” It’s not that a ham will necessarily disqualify a car from consideration based on the ease with which a 2-meter rig can be installed. Rather, he looks at it more as an interesting engineering challenge–the more interesting, the better. After all, if it were easy, it wouldn’t be interesting, would it?
I certainly made things interesting for myself last week when I purchased a 2007 Pontiac G6 GT hardtop convertible. It’s quite a car–200-hp 3.5L V6 (not overwhelming, but adequate), power everything, heated leather seats, awesome Monsoon sound system with XM radio and a 6-CD changer–it’ll be nice and comfy for my half-hour-each-way daily commute.
SENA Bluetooth Adapters with Digital Setting Circles
May 25th
Eddie from Australia wrote me recently to tell me about his success using a serial-to-bluetooth adapter to connect his Digital Setting Circles board to his laptop (avoiding the serial cable which is an obvious tripping hazard, especially in the dark during an observing session). Eddie is using the SENA Parani-SD 200 serial-to-bluetooth adapter connected to the DSC board, and the SENA Parani UD100 USB-to-bluetooth adapter with his laptop.
A Box for the Digital Setting Circles Board
May 25th
A question from a builder of my Digital Setting Circles project caused me to notice a plastic enclosure that another builder had used to contain the circuit board for that project. Oscar’s web page gives a nice narrative on how he built my project, and this page shows a nice enclosure with a clear plastic top he used for the project. The box came from Jameco, and it appears to be part no. 141832. Make no mistake–you’ll have to cut holes in the sides for the serial connector, encoder connectors, and battery connector, but at least the box is about the right size and looks to be easy to work with. I’m sure there are other suitable enclosures out there, as well.
If you’ve used another enclosure and liked the results, leave a comment below and tell me about it.
