KB6NU's Ham Radio Blog

KB6NU's Ham Radio Blog

My one-day Tech class “bag of tricks”

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Felix the Cat, with his magical "bag of tricks."When I was a kid, I used to watch Felix the Cat cartoons. One feature of those cartoons was Felix’s “magic bag of tricks.” Whenever he would get into a tight spot, he could make the bag into anything that he might need. For example, he might make it into an airplane and fly away from whatever trouble he had gotten himself into.

It’s even part of his theme song. One of the verses goes,

Felix the Cat,
The wonderful, wonderful cat,
Whenever he gets in a fix, he reaches into his bag of tricks.

When I started teaching one-day Tech classes, it became apparent to me that I needed my own “bag of tricks” to illustrate some of the concepts that I was trying to teach. For example, to illustrate question T6A05, “What type of electrical component consists of conductive surfaces separated by an insulator?” I pass around a ceramic capacitor from the bag of tricks to illustrate this point.

As I came across questions like these, I started throwing stuff from my junk box into a zip-lock bag. I’ve been carting this bag around for 20 years now, and it’s accompanied me all over the country from California to New England.

I’m continually adding items to the bag of tricks. The most recent addition is a short length of shielded cable (question T6D03). I rarely take things out of the bag, so it’s accumulated items that illustrated the answers to questions that are no longer in the question pool. More on that later.

What’s in my bag of tricks?

Yesterday, I got a text from a fellow who is teaching one-day Tech classes. He writes:

Can you kinda make an inventory of your bag of show-and-tell items for the HIAD (ham in a day) class?

Since this bag of tricks has always been sort of an ad-hoc thing, and it’s continually changing, I had never really created a list of items. I replied,

Hmmmm. Thanks for asking. I should probably re-think what’s in there. Give me a couple of days.

And so, that’s why I’m sitting at my desk, with the stuff from the bag of tricks not so neatly splayed out on the desk in front of me. Here’s what’s in there:

  • Photo of the innards of a potentiometer, showing the resistive element and slider.
    This potentiometer is one of the components in my one-day Tech class “bag of tricks.”

    A metal film resistor (T6A01).

  • A 25 kΩ potentiometer (T6A03, T6A02)
  • A potentiometer without the case (see right) that demonstrates how a pot works.
  • A ceramic capacitor (T6A05)
  • An electrolytic capacitor, in case anyone asks about them.
  • A toroidal inductor (T6A06, T6A07)
  • A rectifier diode (T6B02, T6B09, T6B06, T6D01). I’m also thinking about adding a small signal diode, such as a 1N4148 to the bag.
  • Light-emitting diode (T6B06, T6D07)
  • Transistors (T6B03, T6B10, T6B11). I have a couple of transistors in a plastic cases, a metal case 2N2222, and a larger power transistor.
  • A PCB illustrating the circuit in Figure T-1 (T6C02, T6C03, T6D10, T6C04, T6C05).  I designed this board specifically to explain these questions. I will happily send you one for a couple of bucks.
  • 4001 integrated circuit (IC) in a 14-pin DIP package (T6D09). I keep thinking that I should get a big, honking processor IC to show as well.
  • 78M05 voltage regulator (T6D05)
  • A short length of shielded cable (T6D03)
  • A dual-band HT. This can be used to illustrate lots of different questions. The most amusing to the class are when I use it to demonstrate antenna polarization (T9A03, T3B02) and cross-polarization (T3A04). To illustrate T3A04, I hold the radio so that the antenna is perpedicular to the ground and say, “It might look cool to hold the radio like this, but for best results, you really need to hold the radio so that the antenna is vertical.”
  • A “rubber ducky” antenna (T9A04)
  • Coax. I have three pieces of coax in the bag: RG-58, RG-213, and a piece of air-insulated coax. There are numerous questions about coax in the question pool.
  • PL-259 (T9B07). The piece of RG-213 coax has a PL-259 attached.
  • N connector (T9B06). What I had in the junk box was an N connector to BNC adapter.
  • Length of “flat copper strap” (T4A08, T0A09)
  • Clip-on ferrite choke (T7B11)
  • Harbor Freight multimeter. I use this for all the multimeter questions, and I get a good laugh when I discuss T0A12
”Which of the following precautions should be taken when measuring high voltages with a voltmeter?” The answer is, “Ensure that the voltmeter and leads are rated for use at the voltages being measured.” I say that the meter says it is rated up to 1,000 V, but you’ll probably melt the insulation on the test leads and blow up the meter if you do.

Finally, one thing I carry around with me is a vacuum tube. There are no questions on the test about tubes, but I show it to students who seem really interested in electronics. Once I explain how a tube works, they’re fascinated.

What am I missing?

There are probably a number of other things that I should have in the bag. Some that I could probably include kind of easily are:

  • SPDT switch (T6A08). I probably could come up with a simple circuit board for this.
  • Relay (T6D02). I’m sure that I have some of these in my junk box somewhere.
  • Meter (T6D04). Ditto.
  • Length of heavy-gauge DC power cable (T4A03)

There are undoubtedly others. Please, if you have something in your bag of tricks that I don’t have in min, or if you have an idea for something to include, let me know.

 

 

Videos from HOPE: Hackers and hams, HERMES, 3d printing

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Can it ham?

Terry, NV0O, and Andrew, N3OCQ, talk about their journeys into amateur radio and why hackers and ham radio operators have a lot in common.

HERMES: Secure, Long Distance Data Communication Over HF Radio

Peter Bloom from Rhizomatica talk about HERMES, which provides secure, long-range digital/data communications over RF. HERMES was not designed to be used specifically in ham radio, but it will certainly have an impact in our hobby.

Hacking the Layers: Hackers, Open Source, and the 3D Printing World

Jim Griffin gives us a history of hacking, culminating in the invention of 3d printing and the role of hacking and open source in the 3d world.

The EMF Explorer: A badge for ham radio?

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I’m not sure how I discovered the EMF Explorer, but building one has been on my list of things to do for years now. About eight months ago, I even purchased the parts to build several of them, but never got around to it. A couple of weeks ago, I read about a workshop at DEFCON to build one, but I found out about it too late, and I couldn’t sneak into the workshop. Last night, however, I finally built one.

What is an EMF Explorer? According to the designer, Darcy Neal—who describes themselves as a new media artist, cyborg, and educator—the EMF Explorer is an “electromagnetic frequency sensing circuit that lets you listen to the world of hidden electromagnetic frequencies all around you!” Here’s the scematic:

Schematic for the EMF ExplorerAs you can see, it’s a pretty simple circuit. The 100 mH inductors act as pickup coils, and the electromagnetic signals they pick up are amplified by the op amps and output to the headphone jack. To use it, you simply bring the coils close to something that you suspect is emitting electromagnetic waves, as shown in this video:

I’m not sure what all these sounds mean, but it’s been fun to wave my Explorer around at the various electronic devices and AC outlets in my home.

The Explorer shown in the video was made from a kit that you can buy from Make: magazine. It’s actually on sale now for $30. Since I had all the parts, I made my own:

Prototype electronic circuit.

Since this is just a prototype, I left off the power switch and LED. That’s why there’s no battery in the second battery holder. You might also notice that I used a 14-pin IC socket instead of an 8-pin socket. The reason for that is that is what I had in my junk box.

The prototype board is worth mentioning, too. I was originally going to build this on some perf board that I had, but in pawing through my junk box, I came across the Adafruit Perma-Proto Half-sized Breadboard PCB. Each row of holes on this board connect to one another, just like on a a no-solder prototype board.  Building a circuit on this board is much easier than if I had tried making it on a board on which I had to connect all the components myself. Adafruit charges $4.50 for this board, but, of course, you can get cheaper ones on Amazon.

A badge for ham radio?

One of the things that I’ve been impressed by in attending hacker conferences over the past three or four years are the badges. At DEFCON, there was even a Badge Life Village. Some of them are even useful. For example, the badge I got at KernelCon is a mini-weather station.

I think that ham radio is missing the boat by not having cool badges like this. So, what I’m thinking is that a version of the EMF Explorer could be made into a badge for Dayton 2027 (and/or other ham radio events).

To do this, I think we’d need two things:

  1. Artwork appropriate for ham radio
  2. A PCB design incorporating this artwork.

Anyone interested in helping me with this project? I think that I know enough about KiCAD to actually do the PCB design, but I wouldn’t mind having some help with that, and I certainly am not a good enough graphic designer to come up with some cool artwork. If you’re at all interested, please send me an email.

You know POTA. You know SOTA. How about BOTA?

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A couple of days ago, I got an email from Rem, K6BBQ. He writes:

Logos for Bunkers on the Air.I am the national representative for the US Bunkers On The Air (USBOTA) program. I want to share with you what BOTA is and how ham radio is part of this.

Worldwide Bunkers On The Air (WWBOTA) consists of over 20 member countries and is an amateur radio awards scheme (like POTA and SOTA) focused on activating and hunting (chasing) bunkers. Some BOTA sites are also in POTA sites which some activators might find of interest.

The USBOTA program started earlier this year and needs hams to help it grow. The US bunker locations can be seen on this worldwide map.

From coastal fortifications and anti-aircraft emplacements to Cold War command centers, Nike missile sites and civil defense shelters they are silent witnesses to moments of national and international significance. WWBOTA exists to promote interest in them as part of our collective heritage and to connect the amateur radio community with these sites of history.

We invite you to join us — and to know a little about the bunker you visit, not just its reference number.

Sounds like fun to me, but unfortunately, just as there are summits near me in the flat Midwest, there are no bunkers near me, either. At least there are none currently. In a subsequent email, Rem mentioned that Civil Defense sites, such as fallout shelters, qualify as BOTA sites.  He writes:

One other thing included is Civil Defense sites, including fallout shelters. These have been the greatest number of sites I’ve added. I don’t want to send hunters to a place without a fallout sign so I do ask for a photo that can be found from Google Street View or webpage.

There are some websites that claim to list shelter locations but these are only names of places (schools, city hall, fire station.). It’s too vague.  Other sites will be more specific with a photo of the sign and building.

I see you live in Ann Arbor so I decided to check there. I found this. [This page mentions that many University of Michigan building may have fallout shelters….Dan] Unfortunately, what I found was too vague to be included. To have a site included, you need a  description of the location and a photo.

To add a site, you need to make an account on the USBOTA site and then go to the submit a new location page.

I often go walking on campus. I just might scout around and see if I can find any that might still exist and are marked.

Making hams of hackers

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Since I retired three years ago, I’ve made it part of my mission to help hackers get ham radio licenses. Thanks to an ARDC grant, I have been able to teach one-day Tech classes at hacker/cybersecurity conferences around the country.

August is a busy month for me, as there are two big hacker conferences at which I teach. DEFCON, which is arguably the largest hacker conference with 30,000+ attendees, takes place the first week of August in Las Vegas. Hackers on Planet Earth (HOPE), which is run by 2600 magazine, takes place in New York City the week after. For someone who’s kind of a homebody that’s a lot of traveling, so I am glad to finally be back home.

DEFCON: The big one

DEFCON doesn’t release official numbers, but various sources estimate attendance to be more than 30,000 people, making it the world’s largest hacker convention. So, it’s no surprise that my one-day Tech classes are well-attended. Two years ago, we held the class in a large auditorium-type room at the Clark County Library, and we had more than 90 people in the room. This year, we were able to pack 66 hackers into the room at the Las Vegas Convention Center.

Ham Radio Village, which is the organization that handles all the logistics for this class, pre-registered more than 40 people for the class, but shortly after I arrived Thursday morning, people started queueing up for seats that might be available once those that pre-registered had checked in. All in all, we were able to shoehorn in 66 total. Honestly, I’m always overwhelmed that so many would want to take this class.

Overall, the class went pretty well. It was the first time teaching the updated question pool, so there were a few spots where I stumbled a bit. For example, they removed the question, “What is the approximate length, in inches, of a half-wavelength dipole antenna?” So, I had to talk around that when I got to the section on dipoles.

The biggest problem was the room layout. It was long and narrow, and I don’t think that the people in the back of the room could see the white board very well. They probably had a hard time hearing me, too. Next year, we’re going to have to make improvements.

Overall, I had a fairly good result. After the class, 58 took the test and 46 passed. Over the course of the next few days, four more folks who were in the class took and passed the test. 50/58 is a pass rate of 86.2%

There’s always HOPE

HOPE logo.Last week, I taught a class at Hackers on Planet Earth (HOPE). This conference, while addressing many of the same topics as DEFCON, has a completely different vibe. For one thing, it’s held in New York City, which is very much different from Las Vegas. The attendance is also an order of magnitude smaller than DEFCON.

This year, the conference was held at the New Yorker Hotel in midtown Manhattan. The hotel opened in 1929, and was the residence of Nikola Tesla, until he died in 1943. They even have a small Tesla museum with some artifacts from his apartment.

I had a nice room on the 35th floor. It was kind of small, but it had views to the north and west. From our room, we could see Times Square, the Empire State Building, the Hudson River, and if we really craned our necks, the Chrysler Building. And, it cost about the same as my room at the Sahara in Las Vegas.

It was our third time at HOPE, and the first two years, we did the class in a single day. this year, though, they asked if we could split it up into two, four-hour sessions. I was a little hesitant at first, but it worked out OK. The class was much smaller than the one at DEFCON—the first day there were 15 people in the room at some point or another—and some people didn’t return for the second day. But, some people showed up the second day who didn’t attend the first day, so it all evened out. Those that did attend asked a lot of great questions, and I really enjoyed teaching this particular class.

13 out of 14 students taking the class passed the test, and over the next two days, 12 others took the test. All of those passed.

On top of all that, I had a great time in New York City. My wife, Silvia, came with me, and we got to see some of the sights. We visited the Metropolitan Museum of Art, the New York Public Library, and wandered through Time Square. We also took the Staten Island Ferry and visited the 9/11 Memorial. We didn’t do much at night, but maybe next year, we’ll make plans to go see a show or listen to some jazz at a club somewhere.

Changes forthcoming

After teaching two classes using the updated version of my study guide, I think that I’m going to make some more changes. The text for several of the questions could use more explanation, and I think that I’m going to add some more illustrations as well. I’ll be teaching my next class on October 10, here in Ann Arbor, and I’m hoping to get these changes done by then.

Recent SKs: NU2J, K3SHD, K7AJM

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These three SKs all shared our passion for amateur radio.

Marc F. ToussaintMarc Toussaint, NU2J, NU2J

Marc Toussaint, 73, passed away at his home in Bloomfield, NJ on August 5, 2026. Marc shared his father’s love of ham radio and received his amateur operator license from the FCC at age 15. Eventually, he advanced to the Amateur Extra Class Operator License, and also became a volunteer examiner who administered exams to prospective new amateur operators. Marc was a member of the Nutley Amateur Radio Club, serving as treasurer, secretary and club trustee for many years.

Read complete obituary

Casimir “Vic” Bak, K3SHD

Vic Bak, K3shdCasimir “Vic” Bak passed away peacefully at Hospice House in Coeur d’Alene on August 2nd, 2026. Vic was born in Philadelphia and raised in Felton, Delaware. Growing up, he became involved in ham radio, Scouting, Civil Air Patrol, and ROTC……Vic parlayed his lifelong enthusiasm for amateur radio into an illustrious career as an Air Force officer, where he specialized in communications….Vic’s passion for ham radio continued after military retirement. He remained on the airwaves with his callsign K3SHD, connecting with friends near and far.

Read complete obituary

Arthur Movius, K7AJMArthur Movius, K7AJM

Arthur James Movius III-known to all as Jim-passed away peacefully at his daughter’s home in Idaho on June 17, 2026……Throughout his life, Jim’s devotion to ham radio never wavered. From his home on Montana’s Stillwater River, he continued hosting weekly sessions with the Alaska-Pacific Emergency Preparedness Net, remaining an active and respected voice in the amateur radio community.

Read complete obituary

 

 

Question pools should make teaching classes easier

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Last week, I taught a one-day Tech Class at DEFCON, arguably the premiere cybersecurity/hacker conference in the U.S. It was my fourth year teaching this class under the auspices of the Ham Radio Village. This year, there were 66 people in the class.

It was my first class with the updated question pool, and somehow, they’ve made it even more difficult to teach classes with this question pool. For example, they eliminated the question that required an applicant to calculate the length of a six-meter, half-wavelength dipole antenna, but kept the questions:

  • T9A10: In which direction does a half-wave dipole antenna radiate the strongest signal?
  • T9A05: Which of the following increases the resonant frequency of a dipole antenna?

What this means is that I have to basically teach the same material that I taught last year, but now this amount of class time covers only two questions instead of three. And, I’d argue that knowing how to calculate the length of a half-wavelength dipole antenna is more relevant than many other questions on the test.

On top of that, they kept a bunch of irrelevant or obsolete questions, including:

  • T7A02: “Which term describes the ability of a receiver to discriminate between multiple signals?”

I’d argue that in the era of software-defined radio (SDR), the selectivity specification is hardly relevant any more. Obsolete questions like this one make it more difficult to teach the class because I have to apologize for teaching irrelevant topics. There are other obsolete and irrelevant questions in the question pool.

In my humble opinion, the question pool needs to become less of a random collection of questions and more of a teaching tool. The question pool should not only test technical knowledge and knowledge of rules and regulations, but also make it easier for ham radio instructors like me to teach newcomers what they need to know to become successful radio amateurs.

Ill be making some suggestions on how to do that in the future, too.

 

One lump or two (or three)?

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If there’s anything that radio amateurs like to kvetch about it’s licensing. How many license classes should there be? How difficult should the tests be? What kind of privileges should each class get?

Back in the 1950s and 1960s, the debate was incentive licensing. Incentive license was supposed to be an effort to get radio amateurs to upgrade their technical skills. As you progressed up the ladder from Novice to Extra, you received more operating privileges, mainly on the HF bands. In practice, however, it stripped privileges from General Class hams, and so many of them got upset with the ARRL—which backed the program—that I believe it was the start of the ARRL’s demise.

In the 1990s and early 2000s, the debate was about whether licensees should be required to pass a code test or not. In 1991, the first no-code Tech licenses were issued. In 2003, the World Radiocommunication Conference (WRC) in Geneva voted to allow International Telecommunication Union (ITU) member countries to eliminate the mandatory Morse code proficiency requirement for amateur radio licensing. In 2007, the FCC eliminated the Morse code testing requirement for all amateur radio license classes in the U.S.

In April 2000, the FCC stopped issuing new Novice, Tech Plus, and Advanced class licenses, leaving just Technician, General, and Amateur Extra as the classes available to new applicants. Being an Advanced Class licensee at the time, I was hoping to get Extra Class privileges, but unfortunately, that was not to be. I remained an Advanced Class license until 2005, which is when I started publishing study guides. After all, who would want to buy an Extra Class study guide from a guy with only an Advanced Class license?

Fast forward to today

Steve, N8GNJ, the fellow behind the Zero Retries newsletter, is trying to re-ignite this debate.

(By the way, if you haven’t already subscribed to Zero Retries, you really should, at least if you’re concerned about the future of the hobby. Despite the way he capitalizes “Amateur Radio,” a la the ARRL, it’s well worth reading. And, it’s completely free, although Steve is very happy to accept donations.)

In issue #258, N8GNJ published an article titled, “Fixing the US Amateur Radio Licenses.” The article, which references a blog post by Bob, K0NR titled “How to Fix the Technician License,” In it, he says that many new hams aren’t all that interested in HF, and consider the current license structure, which is a holdover from the old incentive licensing days, to be a disincentive for upgrading only to obtain more HF privileges. He says that the current licensing structure, “smacks of gamesmanship / hoop jumping / jerking them around, and simply, [new hams that Steve calls “new tech hams] have no patience for such things.” I think that he’s right, up to a point, about this.

Steve proposes that we combine the US Amateur Radio Technician and General Licenses into a single license that has all the privileges of the current General Class license and to promote all of the current Techs to this Standard Class. He would make the test for this Standard Class a bit more challenging technically, adding questions about digital technology and software-defined radio, topics which he feels are more relevant than “arcane radio circuits or formulas that aren’t necessary to operate with current off-the-shelf equipment.”

This article has started an interesting discussion on the ZeroRetries discussion group. There, the idea of a two-tier license structure is quite popular, although the form of that structure varies from person to person.

Several advocate for just a single license class and test. I’m not sure that’s a good idea, as you’d have to make that test quite difficult, and that would discourage many people. One fellow suggested a single class of license with endorsements for things such as “VE/VEC stuff, spread-spectrum operation, high-power operation, encryption, and Operational Compliance Observer (Radio Police).”

All of these ideas deserve discussion. Unfortunately, as in many other areas of amateur radio, the current version of the ARRL lacks both the vision to and leadership necessary to move this forward. Personally, I’d like to stop kvetching and really start working on how to improve ham radio.

 

 

More QSLs: N7FAN, AD7HI

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These QSLs are a bit different than the other QSLs I post here. Not because they don’t spell words, but because they are from stations west of the Mississippi. Because of the way I have to mount my HF antenna, I don’t do very well to the west. Also, the N7FAN card is for a rare FT8 contact.

More POTA notes, 7/30/26

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Here are a couple more POTA notes:

  • I’ve discovered the limits of my 9 Ahr BioEnno battery. I used it for the following activations:
    • July 22, 1 hour, 15 contacts
    • July 24, 1.5 hours, 31 contacts
    • July 25, 1.5 hours, 60 contacts
    • July 27, 2.5 hours, 52 contacts
    • July 29, 1.25 hours, 40 contacts

    About midway through this last activation, my KX3 began limitng the power output to 10 W. I guess that the battery couldn’t supply enough current to output the full 15 W. It did continue to work at 10 W, though, for the remainder of the activation. I recharged the battery overnight, and it worked just fine this morning.

  • My 40 contacts yesterday gave me 940 from the Iron Belle Trail (US-13184), so this morning, I decided to work the remaining 60 to get my “kilo” for the park. I made my first contact at 8:35 am, and for the next hour and a half, did pretty well. I made contact #59 at 10:05, which is close to 1 contact every minute and a half. Then, the band went south on me. Over the next half hour, I only managed 7 contacts.Even so, that put me over 1,000 QSOs for US-13184, so I’m happy about that. My 1,006 contacts and 29 activations don’t, however, get me onto the leader board, though. KE8VC leads with 117 activations and 6234 contacts!
  • After lunch, it was such a nice day that I managed to cajole my wife to head out to the Pinckney State Recreation Area (US-3322) with me. The bands weren’t as cooperative as they were in the morning, but I did manage to make 40 contacts over the course of two hours. I would have liked to make more contacts, but it was fun just chilling by the beach and enjoying the day.

    Towards the end of the activation, a young man and his son came up to me and started chatting. He mentioned that he was planning to take the Tech test soon. I gave him my card and encouraged him to download my free study guide. I also gave him a demo of my POTA setup and explained what POTA was all about. I hope that he will get his license soon and join us on the air.