KB6NU's Ham Radio Blog

KB6NU's Ham Radio Blog

Gear/Gadgets

Keysight White Papers: Make better DMM measurements, choosing a benchtop power supply

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Head shot of young man with dark hair and a beard.
Yours truly, back in the day, when I was a writer and editor for TMW magazine.

Back in the day, I used to be a writer and editor for Test&Measurement World, an electronics engineering trade journal. Well, I’m still a test and measurement nerd, and  I enjoy reading white papers like these from Keysight, which is the current name for the test instruments division of what used to be Hewlett Packard.

Here are three that I’ve come across lately:

  • DMM Tips to Eliminate Errors and Maximize Accuracy
    When making measurements with a digital multimeter (DMM), common errors such as signal interference, external noise, and internal current leakage will cause measurement errors. Understanding the root cause of these errors will help you eliminate and achieve the greatest accuracy possible using a DMM. This white paper covers several sources of system cabling and DC voltage measurement errors and the solutions to get the accuracy you need. Learn how to tackle the following measurement challenges while using a DMM to measure DC: common mode rejection, noise caused by injected current, loading errors due to input resistance, loading errors because of input bias current.
  • Make Better AC RMS Measurements with Your Digital Multimeter
    If you use a digital multimeter (DMM) for AC voltage measurements, it is important to know what type of reading your meter is giving you so that you can properly interpret the results. Is your meter is giving you peak value, average value, root-mean-square (RMS) value, or something else? If the answer is “something else,” you may be in trouble, and the trouble usually happens with AC rms measurements. This application note will help you understand the different techniques DMMs use to measure rms values, how the signal affects the quality of your measurements, and how to avoid common measurement mistakes.
  • How to Choose a Benchtop Power Supply
    When deciding which bench power supply you need, it’s easy to be overwhelmed by the many options available. When selecting a general-purpose bench power supply, you should consider multiple factors and understand the important features. For a basic power supply, you can select one based on your voltage and current requirements. For specialized requirements with source and measurement features, selecting from a set of power supplies to meet your needs is straightforward. Identifying the application you need helps you narrow down your options.

What do you think of this artwork for the ham radio EMF Explorer

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Ever since I discovered the EMF Explorer I though it would make a good badge for amateur radio. It’s a simple circuit, it’s easy to build, and does something amusing and interesting. I actually built one about a month ago.

Since then, I’ve been talking with a couple of guys who are interested in doing the PCB layout for my ham radio version, and I have been working with an artist on the artwork design. Here’s what’s she’s come up with so far:

It might be a little busy, and it’s going to need some modifications to accommodate the vias and the component designators, but overall, I kinda like it. I would like to hear what you think about it, though. Please email me or leave a comment below.

ICQPodcast Episode 494 – Q and A 2026

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ICQ Podcast logo.In this episode, I join Martin Butler M1MRB, Caryn Eve Murray KD2GUT, Edmund Spicer M0MNG and Ed Durrant DD5LP to discuss the latest Amateur / Ham Radio news:
The episode’s feature is Q and A 2026.

Videos: What’s next for POTA, ham radio helps rescue man trapped in cave

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What’s next for POTA?

I sometimes claim partial credit for POTA because Thom, W8TAM, was in one of my General classes. Maybe that qualifies me for one-half of 1%? one-quarter of 1%? Thom always teases me that I’m “ham famous,” but I think his work on Parks on the Air (POTA) is making him way more ham-famous that I can claim to be. Here he is on the Q5 Worldwide Ham Radio video channel, explaining some of the changes coming to this popular program.

Amateur radio tech aids Canadian cave rescue

On the next episode of the ICQ Podcast, we are going to discuss an interesting cave rescue story. As it happens, we believe that five-watt QDX-M transceivers from QRP-Labs, operating on the 2200m band, were used to communicate through 100 meters of solid rock in the rescue operation at Rats Nest Cave in Alberta, Canada. The rescuers used  JS8-CALL digital mode to send and receive text  messages with the trapped man. Here’s a news report on the rescue:

 

The Calgary Herald also published a story on the rescue on August 21, 2026.

For more information on the technology, you might want to read the recent article in MAKE: magazine, “Cave Radio – Talking Through Solid Rock.”

ICQPodcast Episode 485 – World Cup Special Event Station

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ICQ Podcast logo.In this episode, I join Martin Butler M1MRB, Caryn Eve Murray KD2GUT, Edmund Spicer M0MNG and Ed Durrant DD5LP  to discuss the latest Amateur / Ham Radio news. Here are this episode’s topics:

This episode’s feature is a discussion of the World Cup 2026 special event stations.

Videos: The Heathkit story, how orchards became Silicon Valley, and a propagation monitor

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The mistake that built Heathkit

I hadn’t heard the story about the boxcars of electronic components before.

How orchards became Silicon Valley

I worked in Silicon Valley right after I got out of college.It’s interesting to see how it’s changed since then.

Shortwave propagation monitor

I’m not sure how useful thing would actually be, but it’s a simple project and could be interesting.

From my inbox: Free antenna book, new zBitx, how to get back into the hobby

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I’m on a lot of amateur radio mailing lists, so I get a flood of information every morning. Here are three items I found amusing in this morning’s email…..Dan

Free antenna booklet

Jukka Siitari, OH2AXE/SV9RMU, has just published Amateur Radio Antenna Systems, and it is available as a free PDF. This 62 page guide was written for beginners, but more seasoned radio amateurs will find useful information, too. For example, I found the chapter on selecting and locating an antenna interesting.

This illustrated guide is available in English, Spanish, Portuguese, German, and Greek. Should you need versions in any of these languages, please get in touch with SRAL office by email: [email protected].

Drawing of a horizontal loop antenna.
This 62-page antenna booklet contains many photos and illustrations.

HF Signals releases the zBitx v2

According to Ashar Farhan, the zBitx v2 is finally here! He writes:

The zbitx v2 is two things : it is an upgrade of the original zBitx radio and it is also a new zBitx software that  fixes almost all the issues reported by the users.e to the supply problems around the display and the raspberry pi zero 2W and increased freight and duties all around, our price to be be increased. the zBitx v2 now retails for $269 (including shipping).

This does look like a nice update to this very small rig. For more information, visit the HF Signals website.

Picture of a small radio.
The zBitx measures just 6.5”x3”x1.5” and runs off two LiPo batteries.

Redditor asks for help getting back into the hobby

Redditor Cold-Description-586 writes:

An old teacher of mine that became a friend had an interest in ham radio. He gained his technician license, bought a radio, antenna, power supply, and wired everything into a shed. It was fun and enjoyable enough that I became interested in it and passed my technician test while he got his general and started transmitting 10 meters. I found this to be really interesting, however, he passed way and my enjoyment of the hobby ended. I’m curious how I could rekindle my enjoyment for the hobby being I have no immediate friends that like amateur radio and have forgotten many techniques of the art.

Here are some of the replies:

  • Get into POTA!
  • If you still have some gear, just turn it on and start listening. Make a few contacts. If you don’t have any radios, tune around on a WebSDR and listen. See if that interest is still there.
  • Identify which part(s) of [the hobby] intrigue you, and focus on those.

What suggestions would you have for Cold-Description-586?

Operating Notes, January 5, 2026

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Screen shot of an IC-7610 band scope.
I’d recognize this signal anywhere.

It used to be that you could recognize an operator by the sound of their fist. That is to say the distinctive way that they sent dits and dahs while operating Morse Code. With the advent of the electronic keyer, fists have become less distinctive, but it’s still possible.

But, there’s another way you can now sometimes recognize an operator. You don’t even have to hear them send a single dit or dah. The key is what their signal looks like on your waterfall.

Yesterday, just after I turned on the radio, I saw a signal around 7022 kHz. Immediately, I knew who it was. I tuned it in, and sure enough I was right. This signal is a little more recognizable because it’s from a homebrew rig, but even so, other signals can probably be determined from how they look on the waterfall if they’re strong enough.

Straight Key Night 2026

As I’ve mentioned before, the only time I use a straight key on the air is Straight Key Night. This year, I only made four contacts before I put the Bunnel #9 back on the shelf. Even though I made only four contacts, two were notable:

  • I1MMR. If you live in the eastern U.S. and operate 40 meter CW at all, chances are you’ve worked Mauro, I1MMR. This was my 42nd contact with Mauro. This wasn’t strictly an SKN contact, but I’m counting it.
  • N0AX. Ward Silver is one of those hams that everyone seems to know. He’s the author of Ham Radio for Dummies and has edited the ARRL Handbook. Signals were S9 both ways and we had a nice chat before my wrist started to quit on me.

Short skip on 40 meters

Every once in a while, I get some really short skip on 40 meters in the evening. A couple of days ago, I worked a fellow who lives near Lansing, MI that QRZ.Com said was about 50 miles away. That’s gotta be too far away for ground wave, so it must be really short skip.

Right after that contact, I worked a guy near Bad Axe, MI, which is in “The Thumb.” (Take a look at a Michigan map, and you’ll see what I’m talking about.) He was only 110 miles away, according to QRZ.Com. Both stations were S9 here in Ann Arbor.

Videos: 44 years of 44Net, Linux HT, Super Rybakov antenna

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44 Years of 44 Net

44 years ago, Hank Magnuski, KA6M, asked for some IP addresses for ham radio experimentation. He was assigned a /8 block, or 16,777,216 addresses. We now know this block addresses as 44Net.

The Linux HT

Can you really run Linux on an HT? Yes! Watch this video and see how it’s done.

The Super Rybakov

This talk by Max, G4SDX, to the Halifax & District Amateur Radio Society introduces a hands-on build of the “Super Rybakov” – an improved version of the classic end-fed vertical antenna. This looks like a great limited space antenna with efficient, multiband, HF performance.

It’s almost like I have a new radio

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Man sitting at a picnic table in front of an amateur radio set.
Yours truly hunched over my KX3 at a picnic table at Grand Mere State Park. Photo: Dinesh, AB3DC.

A couple of months ago, Dinesh, AB3DC, and I were talking about our IC-7610s. Both of these radios were early production units and the displays exhibited the “image retention” problem. (Oddly, even though it was widely discussed when the IC-7610s first came out, I wasn’t able to find anything on the internet describing the problem, although there were several posts with the warranty repair notice.)

As we discussed this, it occurred to me that we have an authorized Icom Service Center here in Michigan (SAR Technical Services), and that we might be able to have both radios serviced at the same time and avoid shipping charges by driving the radios over to SARTS. So, I emailed Matt at SARTS and proposed this to him. He was very agreeable to this, and after checking the serial numbers of our units to make sure they qualified for the warranty repair, he replied that it would be a couple of months before he could get the displays.

A couple of weeks ago, I got an email from Matt saying that he now had the parts, and we arranged to bring the radios over to him yesterday, October 9. In order to make sure that he could get both radios serviced, Matt suggested that we get there by 9:00 am. Because it takes about two hours and fifteen minutes to get to St. Joseph, MI, where SARTS is located, from Ann Arbor, MI, where I live, we started out while it was still dark. After an uneventful drive, we got there just after 9:00am and dropped off our radios.

Since we had five or  six hours to kill, I had suggested that we take our POTA gear along and activate a couple of parks. The park closest to St. Joseph is Grand Mere State Park, so we stopped there first, arriving a little before 10:00 am. It’s a rather small park, without a lot of amenities, and as it turns out, it was quite a hike to get to the beach from the parking lot. We got partway in, and after trudging up one sand dune, and finding that it was still a long way to get the to beach, we retreated to a picnic shelter close to the parking lot. We set up my 66-ft. doublet antenna, making sure to avoid any poison ivy, and I made 13 CW contacts in a little less than 20 minutes.  I then passed the antenna over to Dinesh, who made 13 FT-8 contacts in about 25 minutes. We then packed up and headed to Warren Dunes State Park.

Warren Dunes is a great park. Since we were there on a Thursday afternoon in the fall, there weren’t many people there, but I can imagine that it gets quite crowded on a warm summer weekend. You can tell that it was made to hand a lot of people. It even has a gift shop!

Man sitting at a picnic table on the beach at Warren Dunes State Park.
Dinesh, AB3DC, enjoying the sunshine, the beach, and the propagation at Warren Dunes State Park.

We set up on picnic tables just outside a pavilion, and I pounded in the stakes holding up my telescoping mast easily into the sand there. I managed 14 CW contacts in 19 minutes and then passed the antenna over to Dinesh, who made about 20 FT-8 contacts in a little over 20 minutes. By the time we packed up, it was a little after 12:30 pm and time for lunch. We found a little brewpub in a nearby town and enjoyed a glass of beer with our sandwiches.

After lunch, we stopped to charge my friends car (he drives an EV), and just as we were on our way to the charging station, Matt from SARTS called and said that our radios were ready. After charging the car, we headed back to St. Joseph to pick up the radios.

When we got there, Matt explained what he had done. For me, Matt had not only replaced the display, but also the clock battery (free of charge). In addition, he upgraded the firmware to the latest version. The invoice also noted that he tested transmit and receive functions, the antenna tuner and antenna tuner connector, the CI-V connector, and the USB and DVI ports. My friend’s radio received the same services, except his clock battery was good, so it was not replaced.

Matt also replaced the power connector on my radio (he called while we were at Grand Mere SP to get my approval), as the tabs holding it to the back panel had become compressed and was kind of just floating there. The charge for that was $35.

I was pretty tired when I got home, so I took a nap, then ate dinner before hooking the radio back up again. When I did, the first thing I noticed is how bright the screen is. Seriously, it almost feels like I have a new radio. I had to actually turn down the brightness to operate it comfortably.

An amateur radio sitting on a desktop.
My “almost like new” IC-7610 in action.

Having to get a radio serviced is usually a real pain. You have to box it up and hope it gets there in one piece. Then, you have to wait for the radio to be worked on and for it to be shipped back to you. By contrast, this was a really nice experience.  Although the drive was a little long, we were able to get our radios serviced the same day, and we each activated two new parks. The weather even cooperated. I was a little concerned that it would be kind of cool, but with the temperature in the lower 60s, it was just fine. Thanks to my friend who did all the driving and to Matt for a great service experience.