brainwagon

This morning, I decided to take the new box that I had acquired and remount my K1EL keyer into it. The new box is somewhat larger, so it actually has space for all five of the possible dedicated buttons that the K1EL supports, instead of the mere three that I had haphazardly bored into the previous incarnation. I was a bit more careful to make sure that there was sufficient internal clearance. As it was, I still had a single minor issue: the input jack can actually make glancing contact with the button cell. A quick fix was found however, I simply stick a piece of post-it note to the jack, and that was enough to break the contact.

I didn’t have time to wire up all the additional switches, but they are at least all mounted, and maybe next week I’ll get them all wired in. I’m quite pleased with the overall result this time: I don’t think I’ll need a third try.

Addendum: I realized yesterday that I didn’t have a complete drill set anymore. I was in the neighborhood of Harbor Freight, and picked up one of their cheap 29 piece sets. I was going to drill a 1/4″ hole, so fetched out the 1/4″ from my new set, chucked it in the drill press, and…

It was bent.

I have gotten smaller diameter drill bits that were bent before, but not 1/4″. Annoying.

I woke up this morning, and wanted to relax a bit before the day’s exciting activities (more on this later), so I noted that NOAA17 was coming up. I got out after the pass (which had a maximum elevation of under 15 degrees) was under way, but the audio sounded pretty clear, so I recorded the audio and got the following picture:

Because it was so short, I wasn’t 100% sure what I was staring at. The water at the lower right was (I suspected) the Gulf of Mexico, but I wasn’t 100% sure. So I got out my mapping software and plotted the path of NOAA17 along the ground. Sure enough, that seems plausible.

I should figure out how to plot the visible region for NOAA passes, so I can do this more routinely. In fact, I could probably merge this with my satellite prediction code to give the ground tracks of satellites more routinely. More stuff for the future!

Well, this morning I decided I wanted to get the K1EL keyer that I put together mounted in a proper aluminum case. The sad thing was, I didn’t really pay enough attention to internal clearances, with the net result that I did a pretty crappy job. I’ll probably try again sometime soon, but in the mean time, it’s at least functional, and is no longer at risk of being yanked apart.

Yesterday’s linked article about negative resistance oscillators got me thinking about the possibility of creating a radio where literally every component was made by hand. Okay, I’m not quite ready to make my own wire, but the zinc oxide oscillator that Nyle Steiner seemed like it was only one step away from reaching a reasonable approximation to that goal: instead of a transistor, it used an oxidized strip of zinc. Making potentiometers and capacitors isn’t that hard: the book Voice of the Crystal will give you some ideas about those.

The one element that seems like a specialized, manufactured bit of kit is the quartz crystal. But I suspected that even this could be manufactured, I just didn’t know where to look for information. But then I rembered that my ARRL membership included access to historical back issues of the QST magazine archive, going back to the time of World War I. Sure enough, a short search later uncovered a pair of articles from 1935 by Ivan Loucks, W9ON. Sadly, I can’t reproduce links to the articles here (they are copyrighted), but the first is from the Jan, 1935 QST, and is entitled Cutting Quartz Crystal Plates and the second from February is entitled Grinding and Finishing Quartz Crystal Plates. Combined, the two articles give a pretty good description of how quartz crystals can be cut from raw quartz, dimensioned and then ground and polished into crystals suitable for making oscillators.

This information opens up the possibility that you could make a radio transmitter with no premade components. I think that’s pretty interesting.

Addendum: Here is a history of the development of quartz crystal technology. It pointed me at an additional pair of articles about crystal control by J. Herbert Hollister from 1928 and 1930 in QST. From the article Quartz Crystal Facts, Hollister opens with this:

With just a year of the narrowband era behind us, we find the ranks of the quartz crystal exponents growing daily. At this time last year most of us thought crystal control was only some trick arrangement for the other fellow to play with and squander his money on. There were few, however, who did not envy the crystal controlled station with the beautiful bell-like note which was always to be found at exactly the same point on the dial.

The Spark, Bang, Buzz website has a lot of really interesting low cost electronics experiments involving homebrewing electronics components. Like making your own vacuum tubes, cathode ray tubes, and negative resistance devices. The last is very cool: using a heat treated piece of zinc, you can make a simple oscillator which was documented in the following youtube video. I’m gonna have to try this sometime.

The transmitter sounds a bit chirpy, but check out the schematic! It’s pretty darned simple, it’s hard not to accept a little chirp.

Courtesy of Bill Meara over at SolderSmoke, check out this link to the HF Beacon for MIT Atlantic Balloon Program. It’s a pretty simple 1.5w transmitter for 30m that could be built for about $25. It’s heart is a 74HC540 octal inverter chip, and uses two 2n7000 transistors. Very neat!

When you get an amateur radio license, you are issued a callsign. Mine was KF6KYI. This was a “2×3″ call, which means it had two digits, followed by a single region digit, followed by three letters. These are issued sequentially, which means they aren’t particularly aesthetic or short. If you want to spend a grand $14, you can request a different (usually shorter, but sometimes with just some special meaning to you) callsign by the “vanity callsign program”. The shortest “1×2″ calls are fairly rare, so they actually have a kind of lottery system to reassign ones that have expired.

Net result: I am KF6KYI no longer.

I am now:

Today I had a few minutes to finally put together this pair of small Morse paddles that I got from American Morse. They have a very nice “milled aluminum” aesthetic that I like a lot. By themselves, they are a little light, and tend to float around a bit, but they include a tapped hole that can be used to secure them to a board. I’ll probably use a little wooden plaque from a craft store, and mount my K1EL keyer on it as well to create a little mini Morse station that I can use with some of the QRP kits I’m building/planning to build. Or, I could simply hook it to my FT-817. It’s got a built in keyer even. Not sure yet.

Addendum: I was still bored while waiting for my wife to show up, so I went ahead and soldered together my K1EL keyer kit, pictured to the right. I only had one real problem: the instructions claim that when you insert the battery, you should hear the dit dah dit (R) through the small builtin speaker. I didn’t. I was confused. I checked the voltages between supply and ground. 3.2v, just as it should. The chip was getting power. I puzzled for a while, then suddenly realized there was a jumper that I needed to install to enable the small piezo speaker. Once I did that, all was well. Now, all I need is the proper cabling and a nice box (Altoids tin?) to mount it in, and I can use it with my new paddles.

Addendum²: Today I hacked a little 1/8″ stereo cable and wired it up to match the requirements of my FT-817ND. I’m a complete rookie at this Morse stuff, but I thought I’d record a quick little video to show how it works, using my Canon digital camera. The audio on this thing is a bit weak, but you can get the picture. I had to hold the key down with one hand because otherwise it tends to walk around a bit, I have a block of wood that I’ll eventually bolt it to.

I needed something to read on a plane trip this last weekend, and a quick stop at Ham Radio Outlet had me leaving with a copy of Hands-On Radio Experiments by Ward Silver, N0AX. Ward writes the “Hands-On” column each month in QST, and this book is nothing more than five years of his columns collected in one slim volume. If you have been an ARRL member and received QST for the last five years, you won’t find anything new, but if you haven’t (as I haven’t) you’ll find a bunch of neat articles, each one of which explains a short, concise bit of radio theory, accompanies by an experiment that you could run with a bare minimum of expense. I am looking forward to doing some of their oscillator and amplifier experiments. I recommend the book for someone who likes to learn things through experimentation.

Addendum: Some of the experiments do require equipment which the absolute beginner might not have (like an oscilloscope, which I still lack), but the majority can probably be done with a decent voltmeter.

Two of my current interests…

The 15 meter band continues to be pretty strong today. I was getting mostly South America, but tuning around, I heard E51JD calling from Cook Islands tonight. I turned on the recorder and got this:

E51JD from the Cook Islands

I’ve been meaning to do this for a while: toss together a cheap Yagi antenna suitable for listening to AO-51 on 70cm. If you just google for “cheap yagi”, you’ll find the link to the design. An hour, some 12 gauge aluminum (not optimal, but what I had on hand), a poplar stick, some coax and hot glue, and voila. I have an antenna! Now all I have to do is wait for something to come overhead to see how it works.

Addendum: It works pretty darned good. Maybe just a little worse than my Arrow, but that’s just a guess. I was listening to N6PAA on the QRP repeater on AO-51 just a few minutes ago, and his signal was good and strong.

Well, this weekend is the CQ World Wide DX Contest, one of the larger contest weekends. I tuned up to 15m, around 21.259, and found HC8A booming in. Months ago, my 40m direct conversion receiver was initiated with reception of an RTTY signal from HC8N. Both are stations located on the Galapagos Islands. Nifty. Here’s a link to a brief MP3. You can also hear a Costa Rican station operating on the same frequency for the first half or so, then he moved up in frequency a bit.

HC8A, Galapagos Islands (MP3)

Contest exchanges are kind of boring (well, to be fair, REALLY boring) but contests do bring out large stations with lots of power, and allow you to hear zones of the earth that are largely quiet from inactivity.

Today, on wsprnet.org, W1BW announced that Wednesdays would be “Special Activity Days”, and that today’s special activity would be to operate on 20m instead of the more common 30m. Overall, I didn’t get as many spots as I typically get during the day on 30m, but I did manage to get a spot from GW4VBE, which counts as my first cross-Atlantic spot. To celebrate, I created a new WSPR spot map:

I really do need a better antenna.

My Ramsey 40m QRP rig needs a keyer, so I ordered this nifty one from K1EL. I should be able to install it in a Altoids tin or something similar, and have a nice, fully functional keyer. Then, all I’ll need is a key.

Probably can make a key out of an old hacksaw blade and some scrap.