The mad lads working on LinHT have posted a major update on their accomplishments with Rev B. These boards added:

• power management
• USB-C battery charging
• an RF power amplifier
• RF attenuators in the receive path
• a GNSS module

With Rev B boards they have succesfully transmitted M17 over RF.

They are on to Rev C with work on GNSS antenna improvements, audio codec changes, and more.

This is amazing work from a core team of only 3 people:

• Wojciech SP5WWP
• Andreas OE3ANC
• Vlastimil OK5VAS

See also my earlier post on Rev A progress.

This elaborate description of what it took to replace the transparent LCD cover on a Elecraft KX2 is the funniest ham radio thing I've ever read.

I just created and released a new piece of open source software called kiss-tnc-bridge. This daemon bridges Bluetooth KISS TNC clients to TCP KISS TNC servers. Here's why I created it, how it works, and how you can use it.

If you don't have a ham radio license, or if you want to upgrade the license you have, there are many tools and study helps avaialble.

I recently saw a new one called MyHamRadioStudy. It's free and helps you study the questions from the current FCC question pools for the Technician, General, and Extra exams. Here's some additional free alternatives:

• HamStudy and HamBook by SignalStuff
• Ham Radio Crash Course License Test Prep Playlist

And a couple of paid options:

• The ARRL Ham Radio License Manual
• Ham Radio License Exam

If you want to get your Technician license, a few hours of reading and studying using any of these tools can get you there.

Each spring, the Salty Lizard gravel bike race brings hundreds of bikers to Utah's west desert. Most of the course has no cell service, so amateur radio operators provide communication support for the 3 aid stations and drive the SAG vehicles which roam the course. I volunteered to help out at this years event. Here's how it went and what I learned.

Last year Cobra released the Trailblazer series of GMRS radios. Gratefully, they continued to use the same privacy codes as they have previously used. That means the mappings between brands of radios that I describe in my FRS/GMRS Privacy Codes Demystified deep dive work great with the Cobra Trailblazer 250, 450, and 500.

Update: April 5, 2026: Zero Retries is back on substack at zeroretries.org.

Zero Retries has recently moved to a new publishing platform and domain. If you haven't updated your email subscription or missed the transition, it's easy to resubscribe to this outstanding free email newsletter.

Continuing the momentum from last year, Steve and Tina Stroh are planning the second annual Zero Retries Digital Conference on October 16, 2026 in San Ramon, CA. ZRDC will be held in the same city, and on the same day as the first day of Pacificon 2026. You can attend two great conferences in a single trip.

Tina is putting together the speakers and presentations, I can't wait what she comes up with.

Save the date, registration will be open soon, and they expect tickets to go quickly.

There are many digital modes in amater radio. The ones popular on handheld VHF/UHF radios include:

• D-Star
• DMR
• System Fusion
• NXDN
• P25

To use these modes you typically need two things:

• a handheld radio that supports the mode you want to use
• a nearby repeater or reflector that supports the mode you want to use

There are many options for handheld radios. These repeaters are usually connected to the internet which enables communications with others around the world using that same mode. If there isn't a repeater in your area that offers the digital mode you want to use, you are out of luck. Unless you have a hotspot.

A hotspot is a pocket sized low power repeater that connects to the internet and can communicate with your handheld using various digital modes. You can buy commercial devices, or build your own with a Raspberry Pi, radio boards, and open source software.

The Hamspot 5 by Collin K0NNK is a new option which gives you the flexibility and upgradability of your own Raspberry Pi based solution, without you having to do all the tinkering to get something that works.

This looks like a great device, with full duplex operation and a nice looking case. Runs from USB-C power, and connects to the internet via Ethernet or Wi-Fi.

A couple months ago Wojciech Kaczmarski SP5WWP announced the LinHT project. These mad lads buy a Retevis C62 radio and replace all the circuit boards inside with their own. They aim to create an open-source hardware, Linux based, SDR handheld transceiver. Their first boot of the OS happened on August 18.

Last week, Wojciech, Andreas OE3ANC, and Vlastimil OK5VAS hit a major milestone: the radio now works as a complete M17 transceiver.

A few days later, Vlastimil submitted a PR for the first iteration of Revision B of the circuit boards, which includes:

• a 5W amplifier
• new audio codec
• a redesigned power system which can charge from USB-C with simultaneous operation of the radio

Rev B is not yet ready for manufacturing, but I'll be following closely and can't wait to buy one.

Because the market for batteries to charge phones and laptops is so much larger than the market for batteries we 12V output, all the innovation in batteries is happening on batteries that have USB-C Power Delivery output. There are many vendors and lots of products with different characteristics. If you want to use these batteries with amateur radio gear that takes 12V, or that requires an unusual voltage (my UV-5R battery charger wants 10V input), you have to:

• buy this cable from Adafruit which asks the USB-C device for 12V
• connect it to a small buck converter or boost converter to get the voltage that you want
• live with the losses and heat of the buck/boost converter

Now there is another option, the PocketPD. This small device allows you to choose the voltage you want, and it requests that voltage from the connected USB-C power source. You need a modern USB-C power source that supports the Programmable Power Supply mode from USB PD 3.0 and later. As you would expect, there are many USB-C power sources that comply with this standard.

Instead of bucking or boosting the voltage from USB-C, this device just asks the USB-C for exactly the voltage that you want. Very clever.