I want to get back to FPGA design because I have some projects in mind and I did some in the past that were quite fun and very interesting. I am a bit rusty, though, and I am afraid I have to review all my past, and very diluted, experience with FPGAs. This has a […]
Recently I hit a blocker when using journalctl -b -1 did not work. Using the flags ended up in error
The autumn 2025 edition of Tuzla Field Day, Constanța, Romania, took place between 16 and 22 september. A lovely event, an occasion to meet old friends and make new ones.
CM108 has a set of four GPIOs that can be used via hidraw. These can be read from or write to.
Today I did some thermal measurements with my Flir C2.
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.
There is a problem (or I am doing something terribly wrong !) with the coordinate system in KiCad.
I am already one week into the design of the PCB for my new radio node and today I discovered some schematic errors that I had to fix. Running the DRC (Design Rule Check[er]) KiCad threw some schematic parity errors which “occurs when there’s a mismatch between the schematic diagram and the physical PCB (printed […]
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.
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 […]
Update July 11, 2025 Some thoughts and tasks today. The project is the same I2S interface.
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.
These days we are at Tuzla, in the sunny Dobrogea, on the Black Sea coast, for the sixth edition of Tuzla Ham Radio Field Day. From May 21st to May 25th. Amazing for this event is our desire to meet and socialize. In a world and time when people spend more time with bots and […]
While testing my I2S project I ran into some boot issues on the Raspberry Pi 4 host. For what seemed to be some unknown reasons the boot process was completely chaotic, sometimes running well, sometimes hanging. I banged my head for some time looking for a solution until it came to my mind to change […]
RDA1846, the transceiver inside Baofeng UV-5R, Yaesu FT-4XR, SA818 and other radios is no longer manufactured. There are equivalent chips that can be used.
Update September, 2024. Activities and notes while developing the I2S interface for my radio node.
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 […]
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 […]
A couple of days ago I received from a friend of mine a Harris RF power pallet salvaged from a scrapped equipment. This pallet would be able to dissipate apx 300W PEP (black) on a 50 ohm load on ∼800 Mhz. Unfortunately I have no documentation for this. I do have the schematic but is […]
Recently I installed a trial version of the new PCB toolbox from Matlab. From Mathworks website: RF PCB Toolbox provides functions and apps for designing, analyzing, and visualizing high-speed and RF multi-layer printed circuit boards (PCBs). You can design components with parameterized or arbitrary geometry, including distributed passive structures such as traces, bends, and vias. […]
RF prototype boards arrived today from JLCPCB. The service was, as always, very fast and flawless. Seems they have a direct arrangements with Customs because I was not required to pay anything. I ordered 100 pcs for a total amount of 157 euros, apx 1.57 euro per piece. This includes manufacturing and shipment via DHL. […]
Another “tip of the day”. I ran into this while testing some carousels and swiping banners. All needed the associated js scripts to be loaded lastly after the main page/ post content was already available. It seems that using wp_enqueue_script last argument as true will do the trick: Hope you will find this useful. Cheers […]
While working on my new theme for this site I ran into a problem: CSS collapsing margins. Well, from the beginning let me be very clear: this will not be a comprehensive article on this subject. There is already one written by Josh Comeau and is excellent: “The Rules of Margin Collapse“. I urge you […]
I have to confess that I fail to comprehend this obsession for cheap chinese devices. Although I understand the “cheap” part of the rationale, what constantly amaze me is the fact that usually people that buy such stuff are not necessarily financially challenged — a fact that could justify such a choice. Let’s be honest: […]
I discovered this technology rather recently on YouTube and I was instantly hooked by the opportunities. I bet most of you who had to insulate connectors or sections of hardware (like antenna segments, for example) relied heavily either on self vulcanizing tape or on electrical insulation tape. Both had disadvantages but for me the deal […]
The fourth edition of Tuzla Field Day took place this year on 14-17 September, 2023. Some pictures:
Today I received my latest order from Prusa, a TPU filament from ColorFabb along with some bronze inserts for 3D print assembly. Extremely fast shipment by DHL, the package arrived in only one day. Next days I will print some belts for a device that I have and will publish the results and my impressions. […]
This is a general purpose PCB that I designed in KiCad as a helper board for my Manhattan-style mounted RF projects. It allows connection via SMA connector (vertical or edge mount) and BNC. The two completely separated prototyping sections can be interconnected by using the SMAs in the middle or, if you want to save […]
A timelapse of Fusion360 design of the case of the 101dB attenuator project.
Another one in KiCad 7.0. I work on a project these days and I face all kind of weird stuff in KiCad 7.0. While running DRC in PCB editor, I ran into a “Footprint [whatever footprint] does not match copy in library [whatever library]” warning: This seems to be related whenever the 3D file is […]
