Just go to http://soldersmoke.com. On that archive page, just click on the blue hyperlinks and your audio player should play that episode.
http://soldersmoke.com
Dave AA7EE alerted us to this attack. Please follow-up by posting reception reports (and triangulations!) in the comments below. Dave writes:
Recently, an unlicensed beacon (for which read pirate) has turned up on 3579 KHz. It seems to be located somewhere in the Western US, in the tradition of unlicensed HF beacons dating back to the late 80's that were solar-powered, and located in remote areas of the Southwestern deserts. The very first ones were a cluster of beacons around 4096 KHz (a frequency for which crystals were cheaply and easily available).
Anyway, I am equal parts intrigued and miffed by this latest clandestine operation. Intrigued because of the mystery surrounding all such clandestine operations. Where is it? What does it look like? Who built it, and why? I'm also miffed because, well, dagnabbit - it's on our turf!
It can be heard nightly after dark in the West, on both the KFS and KPH SDR's, in Half Moon Bay and Point Reyes respectively. It sends a series of 22 dits, then the call letters KOK, then more dits.
This is an outrage, a travesty, and a direct assault on the sovereignty of all self-respecting CBLA recruits! I call on all denizens of colorburst land to dust off their Michigan Mighty Mites and other plucky little transmitters, and launch the loud, raucous battle cries of CQ, CQ, CQ into the ether. We shall fight them on the airwaves, we shall fight them in our radio shacks while drinking hot chocolate, winding toroids, and reading QST. We shall go on to the end. We shall never surrender!
I'm telling you Bill, when the very foundations of our existence are threatened, there is nothing that a colorburst crystal and half a watt from a 2N3053 transistor can't achieve. By golly, we can do this.
Here we have a Michigan Mighty Mite being modified for AM in Romania, with input from Hungary, and inspiration from Melbourne, Australia (Peter Parker VK3YE). With a very nice shout-out to SolderSmoke.
I really like Ciprian's emphasis on having fun with the electronics.
Dean KK4DAS and I were talking to Mark, a new homebrewer. After we sang the praises of the Michigan Mighty Mite, Mark asked us a good question: How does it really work?
I guess the starting point for analysis is the Barkhausen criteria (that Pete N6QW taught us): essentially you need enough feedback to overcome losses in the circuit, and this feedback has to be in phase with the signal at the input. The MMM is clearly oscillating, so the question becomes, "How does this very simple circuit meet the Barkhausen criteria?"
Here goes:
Even though it is a very simple circuit, it is worthwhile to separate out the things that it has to do:
1) It needs to set the AMOUNT of feedback. This is done by the tap on L1. Too low down on the coil, and it is too close to ground through the .05 uF capacitor (not enough feedback). Too high on the coil and you get too much feedback. This is like an inductive voltage divider.
2) It needs to make sure that this feedback is in phase with the input signal. Positive feedback. Q1 is an inverting amplifier. So it supplies 180 degrees of phase shift. As the signal at the base goes more positive, the signal at the collector goes more negative, and vice versa. But we need an additional 180 degree shift to bring the output signal in phase with the input signal. Here is the key: The crystal provides the other 180 degrees of phase shift. See
I tested this: A 3.579 MHz crystal does provide the needed phase shift: It introduces a shift of about 190 degrees. Check out this very cool picture. The two scope probes are looking at the input and the output of the 3.579 MHz crystal with 3.580 MHz frequency coming from my HP sig gen.
Click on the picture for a better view.
3) It needs to filter out other signals -- the 365 pf variable cap resonates with L1 at around 3.579 MHz. This results in maximum circulating current through L1 at this frequency.
4) It needs to match impedance to the antenna. L2 wound over L1 forms the secondary of a transformer and efficiently moves the energy from the MMM to the antenna. Think about the gears on your bike.
The 10k resistor biases the base of the transistor, keeping it on. The 27 ohm resistors limits the current through the transistor, preventing it from burning up. Note: the 27 and 10k resistors should NOT be connected directly to each other. There is no dot in the schematic. This causes some confusion among builders.
The .05 uF capacitor does two things: It grounds the L1/365pf tank circuit for RF (but not for DC). It is less than 1 ohm at 3.579 MHz. And it helps reduce (smooth out) key clicks (very sudden on-off changes in the oscillation).
Sam WN5C built a Michigan Mighty Mite and then went the extra mile by putting it on the air from a field location. And what a great name this location has for a QRP operation: Lake Thunderbird.
Sam wrote up his experiences for K4SWL's QRPer blog:
Below is a picture of the rig. NOTE THE LOW-PASS FILTER. FB OM. We wouldn't want that rig tearing up the electromagnetic spectrum.
Looking ahead, Sam writes:
Next step is a DC receiver (maybe the high school receiver?) and then a more substantial transmitter married together, I think. This is all incredibly fun.
It is time to put aside (again!) all of the heated ideological arguments about the power level that defines "low power." Just sit back and enjoy this wonderful trip down QRP memory lane.
40673! TT2! And G3RJV's PW Severn - indeed, bow your heads!
Wow, the Ten Tec Power Mite (or Might!) -- I still want one. Same for the Argonaut -- what a great name (sounds like a "magic carpet), and with SSB to boot! I want to join the Argonaut cult!
I have both the HW-7 and HW-8 (the HW-8 is heading to the Dominican Republic). This video makes me want to fire up the HW-7. Maybe on 40.
I found SolderSmoke about six months ago, and it's quickly become one of my favorite podcasts.
I've been a ham since I was 11, but never tried my hand at homebrewing anything. I've always heard how hard it would be, and how a project like a SSB transmitter is just too far out of reach.
You and Pete are inspirational, so I set out to build a simple starter project, the venerable Michigan Mighty Mite. However not just any mighty mite, a usable one, not just a proof of concept. One intended to sit on a desk and look good doing it. Complete with built in low pass filter, tx/rx switching, and an internal dummy load.
I don't know if I accomplished all that, but I did make a contact on it this afternoon. Next logical step I suppose will be to build a DC receiver to sit next to it.
Please find pictures attached, I've learned a lot about what not to do with project, so criticism is welcome.
73! -Jim W2UO
My response:
Wow Jim, that is really wonderful. Congratulations on the build. I've built many of them, but I don't think I ever made a contact with a MMM. FB.
It looks great to me! Indeed, you should do a Direct Conversion receiver next. Maybe do a receiver for 40, then do a version of the MMM for that same band. Then you could
This was Mike Caughran KL7R's last podcast. He died in a car accident shortly after we made this program.
January 13, 2007. Mike's oscillator work. Michigan Mighty Mite. Lasers, diodes, and Einstein. Laser communication experiment. W7ZOI-KL7R QSO on SKN.M0HBR's feedback amps.The new comet. Saturn, Jupiter and calculation of c. 17 meter QSOs. New SPRAT CD.
MAILBAG: China enigma, VE4KEH, M0DAD, GU0SUP, M1CNK, K4AHU, KD4EDM, KG9DK, AA6KI,
VA7AT ON5EX
---------------------
Mike's Obituary from the February 2007 ARRL Letter:
Mike Caughran, KL7R, SK: Well-known low-power (QRP) and homebrewing
enthusiast Michael S. "Mike" Caughran, KL7R, of Juneau, Alaska, died January
22 of injuries suffered in an automobile accident in Hawaii. He was 51.
Caughran may be best known as one-half of the team -- with Bill Meara,
N2CQR/M0HBR -- that created and produced the weekly SolderSmoke podcast
<http://www.soldersmoke.com/>. "I think people were drawn in by Mike's
friendly voice and manner," Meara commented on a memorial page for KL7R
<https://kiwi.state.ak.us/display/mc/Home>. A member of ARRL and the Juneau
Amateur Radio Club, Caughran also wrote articles for the Michigan QRP Club's
T5W newsletter and he was an active ham radio contester. "Mike was one of
those people who you instantly like because of his honest, straightforward
and humble way of talking and expressing ideas," said Mike Hall, WB8ICN, who
edits T5W. "His co-hosting of SolderSmoke provided me hours and hours of
enjoyment." Caughran was an IT professional with the State of Alaska.
Survivors include his wife and son.
Thank you so much to you all... and thank you SolderSmoke for always writing about my learning in homebrew gear. I did finally got my license... just waiting for the paperwork to arrive. But now I'm finally YO6DXE ( DX Explorer lol ). I did found my issue with the power... it seems that it's from the cheap BD139 that doesn't seem to work as expected. I get about 500mW with a 2n2222. So I ended up making another version of the transmitter that I'm really happy about. 73 to you all DE YO6DXE.
Dave K8WPE has been one of the podcast's best friends and one of its most loyal listeners. Dave was recently going through some back issues of SolderSmoke. This sparked a renewed interest in the Michigan Mighty Mite and the Color Burst Liberation Army. Dave sent us some useful links on this subject. (I had forgotten about the .io CBLA mailing list!) Thanks for this Dave, and for all your support and friendship over the years.
Please listen to some of these podcasts as they are very encouraging to any ham young or old that might want to build something, even as simple as a Michigan Mighty Mite transmitter. Here are references to the Michigan Mighty Mite. The podcasts are listed below.
Or the 80 enter one available from the designer (when the 4SQRP Club retires a kit the designer is free to continue to sell them himself) NM0S on eBay for $26.25 shipped:
If you build one of these kits John at 3rd Planet Solar in Gaylord has bags of crystals and a four position crystal switch kit for the Cricket and Pixie. Check him out at
Please pass this on to your friends. Have fun. Build something. Enjoy! One person built the kit and framed it to put on the wall of his shack to PROVE that he could actually build an electronic gadget.
Also there are many who use easily available color burst crystals from old TV sets and joined the Color Burst Liberation Army (CBLA). Check out
After a two-year pandemic hiatus, yesterday the Vienna (Virginia) Wireless Society's annual "Winterfest" hamfest was back. And the weather was in fact COLD -- it definitely felt like Winterfests of years-gone-by.
Club President Dean KK4DAS kindly invited me to participate in a forum on homebrewing. You can watch the presentation STARTING AT 2:04:06 (hours:minute:seconds) here:
It was especially cool to be able to tell the audience about Pete N6QW and Farhan VU2ESE. We talked about Pete's Simple SSB transceiver, the Michigan Mighty Mite and the BITX rigs.
Some observations on the hamfest scene:
-- There are lots of boatanchor radios out there, and it seems like a buyer's market. These old rigs do not seem to be selling nearly as fast as they did a few years ago.
-- There is a lot of older analog test gear on sale too, and it too seems to no longer be as in demand as it was a few years ago. Perhaps the availability of cheap, small, and very effective digital oscilloscopes is affecting the sale of these once sought-after items.
My purchases:
-- A really old beat-up (crashed?) ARC-5 R-23 receiver. I have already extracted the variable capacitor.
-- A nice box of smaller variable caps.
-- 100 feet of 550 parachute cord.
-- Two nice metal chassis/boxes
-- A bag of shaft adapters/connectors
With Armand WA1UQO (left) and Steve Boles W4SB (center)
With Charles AI4OT
Thanks to Dean KK4DAS and the entire VWS team for a great event.
Our friend Jack NG2E is a homebrewer. He is also a Summits-On-The-Air guy. He does much of his SOTA operations along Skyline Drive in the Shenandoah National Park. Jack's Story Map method of documenting this SOTA trip is very cool.
Elisa and I are frequent visitors to this amazing park. Both my kids went to college in the Shenandoah valley, and the park starts just one hour by car west of us. It is a beautiful place. The Appalachian Trail runs through the park; we have crossed paths with "through hikers" who are walking from Maine to Georgia. We have also met up with more than one Black Bear in the park (see below). My son Billy and I launched our Green Hornet rocket from a farm in the Shenandoah valley: https://soldersmoke.blogspot.com/2017/05/still-photos-and-slow-motion-video-from.html
I really like Jack's use of both HF and 2 meter FM. This makes me think that I should blow the dust off my Baofeng HT and bring it out to the Shenandoah next time we visit. Jack's 20 meter CW contact with Christian F4WBN in the Pyrenees added a nice element of transatlantic mountain symmetry.
I know that Jack wants to include a homebrew rig in his SOTA operations. That would significantly add to the already very high level of operational coolness. Perhaps Colin M1BUU or Paul VK3HN could provide some suggestions or encouragement in this area.
I really hope Ciprian can get a license very soon. His homebrew projects alone should qualify him. Ciprian has The Knack. It would be great if the IBEW (especially the European branch) could help Ciprian get some more parts and test gear.
Perhaps its the result of a vaccine-induced relaxation of COVID tensions, but for whatever reason we are seeing a resurgence of interest in the Michigan Mighty Mite and the Color Burst Liberation Army.
Dan AF7O describes his excellent MMM CBLA adventure here: https://af7o.campclan.net/?p=144Extra points for the use of George Dobbs' Ladybird book technique, and for the 3D printed variable cap holder (made by Dan's son).
Yes Dan, rebuild that antenna, build an LP filter, and get that MMM on the air. At the very least you can get some reports from the Reverse Beacon Network. And, as Jack NG2E recently demonstrated, it is possible to make contacts with a simple rig like this:
It sounds great Ciprian! It was really cool to see your video and hear you reference not only the SolderSmoke blog, but also SPRAT, the Michigan Mighty Mite, and Walter KA4KXX. Your little rig has a very fine lineage!
Jack has in his possession one of the 7.123 MHz crystals that Walter KA4KXX sent me back in 2019 (during my ET-2 craze). It seems obvious that Jack should build a Ten Minute Transmitter and use it to check into the Sunrise Net https://qsl.net/srn/.
We are pleased to report that OM Jack, NG2E, has successfully built a Michigan Mighty Mite transmitter, and has experienced JOO (the joy of oscillation). You can see Jack's prototype in the video below:
Jack has his eye on more ambitious homebrew projects, but is wisely taking a step-by-step approach. He described his plans this way:
Capture this MMM into a semi-permanent design: ie, perf board.
Measure performance. What does the carrier wave look like on a scope?
Build a low-pass filter.
Can I amplify the signal? Maybe add an amplifier stage or two. Transistor?
Next, let's look at receivers. Pete & Bill recommend that I build a Direct Conversion receiver. I know Peter Parker (VK3YE) has a simplified version.
I just decided here over the COVID period to head back to basics here and build a Michigan Mighty Mite with a Color burst crystal I had here. And wouldn't you know it, it works! Here's a couple of pictures, it's not pretty at all. Needs to be mounted on something.
From Walter KA4KXX June 21, 2020 Michigan Mighty-Mite: Why So Complicated? The April 2020 issue of QRP Quarterly magazine featured an article by Bob Rosier K4OCE which included a schematic for a “Ten Minute Transmitter” by G4RAW (SK), which apparently first appeared in SPRAT 82 in 1996. It is even simpler than the Michigan Mighty Mite, so this transmitter can truly be built on a solderless breadboard in about 15 minutes, because a complex coil is not required. The only tuning needed was for me to establish the correct value of the output series capacitor. This rig allowed me to check-in to the Sunrise Net (see details in blue text on my QRZ page) today on my very first attempt, and landed me a 549 signal report from 250 miles away. The first photo shows the transmitter connected to a Transmit/Receive Switch mounted in an Altoids box. In the Transmit position the antenna is disconnected from my 1979 Heathkit HR-1680 receiver, which then coincidentally supplies a sidetone at an ideal volume level. That little black pushbutton which can be seen in the second photo serves as my key, and works just fine for a five-minute daily QNI on the Sunrise Net. Of course, part of the secret is having a crystal exactly on the Net frequency, and I have a few left, free to whomever in the Eastern U.S. is interested in building one of these simple Sunrise Net Special Transmitters and participating in our Net.
"SolderSmoke -- Global Adventures in Wireless Electronics" is now available as an e-book for Amazon's Kindle.
Here's the site:
http://www.amazon.com/dp/B004V9FIVW
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