I was pretty busy since August 2024 with a lot of other tasks, mostly job-related and did not have too much time for DIY and tinkering. And this included my SA818 project.
How to write to CM108 GPIO from Svxlink
CM108 has a set of four GPIOs that can be used via hidraw. These can be read from or write to.
Flir C2 thermal imaging of SA818 radio node
Today I did some thermal measurements with my Flir C2.
Raspberry Pi compatible, SA818 radio node
My new radio node that I designed last month is back from production at jlcpcb. Designed in Romania and built in China 😁. This is my first attempt using jlcpcb for the entire manufacturing chain, from PCB creation to part selection and assembly.
New radio node
Today I finalzied the designed for my new Raspberry Pi Zero-based radio node. Designed around SA818 and CM108B sound codec, will replace my old dead-bug style radio node that I used for so many years.
I2S Raspberry Interface (4)
More work today. Some wires got loose and I did some experiments with .asoundrc and ALSA settings. I added a 39 Ω ballast resistor on SDIN and SDOUT lines and put a ferrite core on both wires. The radio node works as expected, absolutely no issues with one exception, a periodic pop that is audible […]
I2S Raspberry Interface (3)
Update July 11, 2025 Some thoughts and tasks today. The project is the same I2S interface.
A Si5351 DIY oscillator project
I have some Si5351 chips that I never used for any projects. I purchased them from Mouser, I believe for an APRS project, long-standing and overdue. That APRS project I started some time ago but I never completed and maybe I should strongly consider to complete. But this is another topic.
I2S Raspberry Interface (2)
Update September, 2024. Activities and notes while developing the I2S interface for my radio node.
I2S interface for Raspberry Pi (1)
Today I managed to connect the Digilent Pmod I2S2 to a Raspberry Pi 4 and have all frequencies generated. This is part of an older project that I left abandoned for a while: a radio node built on Raspberry Pi and using Svxlink. As known, Raspberry boards do not have a proper audio interface and […]
Controller for DR-1X repeater
I made this for a friend. Is a remote controller for Yaesu DR-1X repetear that is installed on Summit Heniu (145.725 Tx -6khz Rx). This is a mixed digital (C4FM) and analogue repeater that is covering almost all northern half of Transyvania and can also be accessed via Echolink YO5D-R, node 54452. This version is […]
Project status – 3D printed antenna rotator (12/09/2021)
This is a short video about the progress of my 3D printed antenna rotator. Unfortunately only in romanian for now, but captions will be created soon.
Jabra Evolve 65 repair
A couple of weeks ago during what should have been a routine firmware upgrade, my Jabra Evolve 65 simply died. Have no idea what happened and maybe that will make an interesting future project, but because this headphone is my main headset used for teleconferences and other communication required by my job, I was kind […]
Time Capsule Repair
Some time ago, my old Time Capsule died. It simply did not start. I read that this is an issue that plague all older (first and second generation) TCs. The culprits are four electrolytic capacitors inside the switching power supply, two 1,500 µF, one 1,000 µF and one 470 µF. The 1,500 µF were badly swolen. […]
AD8307 RF Power Meter III — build
This will be another short post. I also made the GitHub repo public, but please be aware, current design is flawed. If you use it, you acknowledge that you use it on your own risk. Today I managed to build the revision 1.0 of this power sensor, not without some lessons learned. It was my […]
AD8307 RF Power Meter II — boards from JLPCB
I ordered the boards for this project with JLCPCB in China. This is my first attempt of working with a professional PCB manufacturer and I am extremely pleased by the results.
AD8307 RF Power Meter
My first finished KiCad project is a prototype of a RF Power meter with input attenuation built around an Analog Device AD8307. An excellent tutorial about log amps can be read in March 1999 edition of Analog Dialogue. KiCad PCB: And the 3D rendering of the same PCB: The next step will be PCB ordering, […]
Beacon with SiLabs module
This is a beacon project started by my friend YO5VAE. He faced some issues while programming of the Si4463-based module and I thought I might give a hand. I resoldered the entire project on an empty Arduino shield to allow expansion of the project with some additional modules. Below are some pics, but probably the […]
Boards for prototypes
For low frequency projects, a fast way to prototype is using a bare PCB and scratch some dividers that allow “manhattan” style prototyping. I am especially very fond of this prototyping technique and I believe that PCB design should be avoided in the early stages of prototyping. Jim Williams was an artist in such designs. […]
OCXO tests
A couple of months passed since I purchased two 10 MHz OCXO modules from eBay. And, to my shame, I didn’t even tried these. Yesterday I did a quick test and the devices are spot on. Both measured on my TTi TF930 3GHz frequency counter: The OCXO needs apx 10 minutes for proper warm up […]
SCPI on Mac
Some more days passed and some more finishing touches added to my MacSCPI app. It is entirely dependent on hooking the device via the USBTMC driver, but it works fine and is stable: I had some problems with buffer padding and the output it is still not 100% gibberish–free , but I assume I have to play with […]
USBTMC driver for Mac
After some head banging, I finally managed to send SCPI commands from my Mac to my Agilent (Keysight) DSOX2002A. I’ve worked on this since december last year. Almost a year, but I did not spent a sustained amount of effort. I did it just during my free time. I still have a day job that […]
144.8 Mhz TX for APRS (3)
This is a quick update post. The road I took with this little project is slowly getting to a dead end due to what it seems to be a lack of available crystals for 144.8 (like 48.26 or 28.96 MHz, for using the third or fifth harmonic). I believe that, currently, all APRS modules are […]
Low Power Digitally-controlled Dual PSU
It comes a moment for any electronics hobbyist to build a power supply unit. Probably is one of the most useful and basic projects that you can go for. Well… one can easily buy those, but what’s the fun then ? However, the majority of PSUs available on the market are high-power (high-current) PSUs. With […]
Foam board drawer
More than a year ago I posted this. It was the beginning of this blog and the beginning of my personal space for hobbies and small DIY projects, a very crammed and tiny space that I have in my apartment. I cannot imagine how quickly time passed and how less and less available time I have for […]
Dummy Load Prototype – 2
Next steps for my dummy load prototype based on IRF830 N-Channel MOSFET, and a LM328 plus a multi turn pot.
Breakout board for RFM12B prototypes
Today I started to complete the design of the RF12B Breakout Board for various prototyping.
