Another Mighty Mite Success Story!

Bill:

I started listening to Solder Smoke this winter, and I'm now up to episode 81. Since I'm new to homebrewing, I wanted to say that I enjoy the discussion of good projects to start on for homebrewing equipment, particularly the discussion of the Michigan Mighty Mite, which I understand was your first HB TX project. After hearing you mention the transmitter on the show, I looked it up on the Internet and found the schematic. A few hours later and I was on the air. My first contact with it was with KB1TSG, Jim in Randolph VT, receiving a signal report of 449. From my QTH in Monroe, ME that's a distance of 186.5 mi ( 300 km) as the crow flies.
I've learned a lot listening to Solder Smoke over the past two months and listen to it while in the car, at work, and while walking my dog on the back roads of Maine. Thanks for such a great educational and entertaining show.

73,
Neil

--
Neil Caudill
KB1UAL

Free Shipping on SolderSmoke -- The Book

Use Coupon Code Ground 305 and get free shipping on "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm

Don't just buy "SolderSmoke -- Global Adventures in Wireless Electronics"
but check out these other fine Knack-related publications:

http://stores.lulu.com/6sj7comics ("Lid, Kid, Space Cadet" "Sky Buddies" by Jeff K1NSS

http://stores.lulu.com/ian_g3roo (Ian, G3ROO's amazing antenna book)

http://www.lulu.com/copperwood ("Carl and Jerry" books -- scroll down a bit)

http://stores.lulu.com/soldersmoke (SolderSmoke and Bill's other book)

WSPR Direct Conversion Receiver: On the Air and Online

In a testament to the sensitivity of the WSPR system (and I mean that in the technical, not the emotional sense) I got a couple of reports indicating that my very QRPp WSPR signal was, well, a bit obnoxious. I think part of this results from the fact that I'm one of the few people using a double sideband transmitter -- the lack of filters makes my signal look a bit different. But I do have an AC hum problem that shows up on receive screens. And because I haven't worked out the circuitry to allow the WSPR software to move my little transceiver from transmit to receive, I'd been leaving it in 100% transmit mode. I can understand why people didn't really like that.

So, on the theory that it is better to give (reports) than receive, and in keeping with the old idea that all ham radio stations should from time to time RELEASE the push to talk switch and LISTEN, I have magnanimously taken my homebrew DC/DSB WSPR system into receive mode. I'm in 0% transmit. I'm listening all the time, and automatically uploading reports on the stations I hear. Pictured above is the map from WSPR system page showing my spots from last night. Below you can see what my own WSPR system display shows. (I need to adjust my W3PM oscillator a bit. I may be a few hertz off and I am probably missing a bit of the 200 hertz wide WSPR band).

I was pleased to see W3PM's call on my map. An article by Gene provided the inspiration (and much of the circuitry) for my WSPR rig.

My receiver is very simple: The RF from the antenna goes through a low-pass filter directly to an SBL-1 mixer (thanks to Jim -- AL7RV). There it mixes with LO energy from the W3PM Colpitts oscillator. From there it goes to the KA7EXM discrete component AF amp.

You can watch -- almost live -- the stations I am receiving by going to
http://wsprnet.org/drupal/wsprnet/map
just type N2CQR in the box that asks for the call.

20 years after construction... Mighty Mite Makes Contact!

Bert, WF7I, sent us this report from the nuclear reactor building at UVA. You can almost feel the excitment! Congrats Bert!

Bill:

I'm ecstatic to report that my MMM made its first QSO, after almost 20 years, last night at the University of Virginia ham club at the nuclear reactor! I worked W4OEQ, Tom in McMinnville, TN. He gave me a 459 report. I was running about 300-500 mW (hard to tell with our meter) out of the MMM into our inverted vee up high in the trees of Observatory Hill at UVa. I also have three witnesses to the event: our club president, Mark KJ4IEA; club Treasurer Will, KI4LGE; and member Alex, KJ4YWP. I received a round of applause from our group after the QSO was complete!

It was a very satisfying moment to be sure. Not only to make a QSO with this rig from my past and all those memories, but to do it at the re-vitalized UVa ham club, which has its own long, off-and-on history dating back to the 1930s (at least), and to do it with a captive audience! Our club members, mostly younger guys 18-22 years old, have never done CW and always are in a mesmerized/stunned condition when they see me tapping out the dots and dashes, and copying it in my head! Everyone was very silent and focused during the QSO.

72/73!

Bert WF7I

The Return of the Michigan Mighty Mite

Michigan Mighty Mite -- N2CQR/HI8 version

Bert, WF7I, (our correspondent at UVA Charlottesville), wrote yesterday about his past and recent adventured with a little rig that got a lot of us started in the scratch-built homebrew game: The Michigan Mighty Mite. I built one in the Dominican Republic, probably in 1993. I never worked anyone with it, but was really pleased to get the thing oscillating. I still have remnants of it (sans crystal) -- see above. Bert's e-mail and AA1TJ's recent derring-do make me want to dust off that little single FET transceiver for 3.579 MHz that I built in Italy. One QSO would make me happy. At least this minimalist stuff is keeping me away from the regens...

Here's a good article on how to build one:
http://www.qsl.net/wb5ude/kc6wdk/transmitter.html

Here's a site from Dave, WA5DJJ, who built a bunch of these rigs:
http://www.zianet.com/dhassall/Michmitymite.html

Bert's e-mail:

Hey Bill.

The AA1TJ postings on your blog motivated me to unearth my old Michigan Mighty Mite (the "MMM"). For me there's a lot of history, even emotion, there. I built this little rig with my friend AC7CA when we were both finishing up high school. Neither of us knew what was really going on in this circuit, other than some vague thoughts about resonance and that a transistor amplifies.

What was important to us at the time was more the fit-and-finish of the box that it was in, and making QSOs, rather than working out the theory behind the schematic. I'll email you a photo of the box as it stands now. We got a nice, blue plastic project box from Radio Shack, and figured out that those small iPod (used to be called "Walkman")-style headphone sockets made great crystal sockets as well (they really do). I remember vividly the two of us planning out the radio, I remember trying to work with plastic (not so easy, it tended to melt and scuff up), and attaching the air-variable capacitor (not a small feat with the limited tools available). But the end product looked like a much more impressive rig than it really was. This oversized blue box with a big tuning knob, bright colored red and black banana power terminals, the cool little crystal sticking out of the top, and the Dymo-label tape proclaiming, "Rig Master" (or "blaster", or something similar -- I have to actually go see what it said!). 1/2 W of power came out of this very simple oscillator, just as advertised. But to this day, I don't know if either of us ever even made a QSO with the thing! The thrill was in the assembly of a rig from a schematic in CQ magazine, the fellowship of the two of us working on it, and seeing the thing actually WORK as promised. Time moved on, and it ended up getting shoved to a back corner of my room, and when college and work came along, it almost got totally forgotten and collected dust.

Anyway, the blog postings made me think of low-powered QRP, and I dug it out again, dusted it off, and pulled out some crystals. The thing still works just as it did 20 years ago! I was very happy to see that. I guess one of the advantages to ultra-simple, low part count rigs is that not much CAN go wrong! And if it does, it only costs a few pennies, or nothing, to fix.

The rig went on the air on Saturday night, and it was quite an interesting contrast on the work bench. On one side, my Kenwood TS-2000, a state-of-the-art (or nearly so) DSP rig, with the "glowing numerals" and a computer interface. Next to it, the MMM, straight key and a pile of rocks! A single "super antenna" compact vertical was erected on a tripod in my backyard, with a coax coming in to the shack to a switch (functioning as a "T/R" switch, in a way). In one position, my gazillion-transistor appliance rig would function as a ridiculously sensitive and over-the-top receiver for the task at hand. In the other position, my homemade single-transistor MMM would transmit out to the vertical.

I called CQ till my hand/wrist was sore, and QSY'd between the 4 freqs I had to choose from, but to no avail. I am not deterred however. This evening, following the W4UVA club meeting, I will hook it up to our 40 m inverted vee high in the woods overlooking the nuclear reactor. It would be fitting if the possible first ever MMM QSO came from this setup.

Late Sunday night, after I had exhausted myself from "pounding brass", I was reading more from "Solder Smoke -- The Book", and found one picture that really made my day. Sitting in front of your Tandy and just to your left, was a small blurry object. Reading the caption, I saw that it was YOUR Michigan Mighty Mite! What a fitting way to end a wonderful weekend of hamming.

72/73,
Bert WF7I

Happy Pi Day! (3.14 Get it?)

http://www.collegehumor.com/video:1948828

One of the many benefits of having a kid in elementary school is that you are made aware of important days that otherwise might escape your attention. Like today: International Pi Day. While the mathematical connections might be a bit flaky, I liked the above video.
Slashdot put it this way:
I'm not saying it's as good as Lady Gaga or Justin Bieber or something, but it's a great way to get ready for Pi day which is tragically still not a federal holiday. Write your congressman.

Podcast QRM Culprit Found: WBIG-FM 100.3 MHz

Listeners noticed that recent SolderSmoke podcasts had some other audio playing faintly in the background. At first I though this must have been AM broadcast band breakthrough, so I built a little crystal radio, only to discover that the powerful AM stations here were not playing the ZZ-Top style classic rock that I was hearing in background noise. Bert, WF7I, suggested that I listen carefully to the QRM for a call sign. I tried that this morning. I couldn't get a clear call sign, but I picked up the unmistakable rhythm of Peter Frampton's "Do You Feel Like We Do?" Fortunately that song is 1) infrequently played and 2) quite long; I had enough time to take a spin around the FM radio dial. Sure enough, I caught the tail end of the Frampton song on WBIG-FM 100.3 A quick check of the web shows that this is a 50,000 watt station that has its transmitter within about 1 kilometer of my house. Bingo.
The mic cord is just about 1/2 wavelength. That would put the high voltage nodes at the ends, right? I notice that the interference drops noticeably if I wind up the cord, and increases a lot if I stretch out the cord.
I can hear some other stations in there also (one country station). It may be that there are multiple FM stations broadcasting from that antenna site. I can see the tower's red lights blinking from my front lawn.
Thank you Peter Frampton!

Regen Madness

How many times have I said "never again, no more regens"? I guess I need a twelve step program or something like that. This latest bout of regen fever started with the King's Speech movie. So I blame the Brits. All of them. Then this Belgian guy with the video comes along (see above). Now I find myself drawing out a schematic for the old regen that I picked up years ago at the Kemption Park rally in London. Someone please, STOP ME!

Job Opportunity: MAKE needs THE KNACK

Sounds like the folks at MAKE are looking for someone with THE KNACK. Check it out:
http://blog.makezine.com/archive/2011/03/awesome-opportunity-to-work-with-make.html

HomeBREW (literally!) Your Own Microphone!

During those dark days in which I was using my Astatic D-104 mic for podcast purposes (not a popular move) I checked on the mic element inside my chrome lollipop and found it to be the original crystal "Rochelle salt" element. I remember wondering about the Rochelle salt: What the heck was that? Well, this morning, the hippie technologists over at the Make blog explained it all to me via the above embedded video. It turns out that you can MAKE piezoelectric Rochelle salt crystals in your kitchen using -- get this -- soda ash, coffee filters, and -- wait for it: CREAM OF TARTAR sauce! I'm not making this up.