Dhiru's Notebook

In my previous Dual-WAN failover article, I moved from a TP-Link ER605 (slowest device ever) to a MikroTik hEX S.

Could a serious WSPR station need only one small program and one memorable command?

Related work Baby QRO Switching RF amplifier for HF Digitally Adjustable RF PA Supply A new generation of the Baby-QRO switching amplifier targets 10 W to 500W+ of RF output for FT8 and other FSK modes.

The original PVM kernel tree was based on Linux 6.12.x, while current Linux master had reached 7.2.

Live HF band conditions and regional WSPR propagation paths.

The idea is simple: build a low-cost, purpose-built HF receiver around a cheap high-speed ADC instead of repurposing an RTL-SDR.

My new favorite HF antenna is the 1/4 Wave HF Vertical DX Antenna with 2 Elevated Radials.

This is an early design sketch of VHF (2m - 145 MHz) APRS beacons that are small and can be placed in vehicles like ambulances or fire trucks.

This is an early design sketch of a UHF (70cm - 440 MHz) WSPR beacon.

Convert between watts, dBm, dBW, voltage, and dBmV for common RF impedances.

A firsthand account of being scammed by a Shopify merchant, why platform trust matters, and how to protect yourself.

The constraints 5V (~500mA) power from mobile phone 1W RF output required Very compact with less "moving" parts 14 MHz capable The design We use INNOTION YG401530VB MMIC in this design. 100n Si5351 CLK 0 --||----+---------+ | MMIC | | IN | | | | OUT…

I learned about the Sub-1€ TRX challenge from Ismo (OH2FTG) - thank you (maybe for getting me addicted?).

The constraints 5V (~500mA) power from phone 1W RF output required Very compact with less "moving" parts 14 MHz capable The design We purposefully utilize "high Rds" EPC GaN parts with very low Qgs.

The old hack Sometime around 2015-2016, I had to connect two rooms that were separated by a balcony.

Related work Baby QRO Switching RF amplifier for HF A new generation of the Baby-QRO switching amplifier targets 25W to 50W of RF output for FT8 and other FSK modes.

Related work Baby QRO Switching RF amplifier for HF Digitally Adjustable RF PA Supply A new generation of the Baby-QRO switching amplifier targets 25W to 50W of RF output for FT8 and other FSK modes.

Photographers often say: The best camera is the one you have with you.

Running your own AI coding assistant locally using ROCm, LLaMA C++, and Nanocoder.

I recently bought a ceiling fan from Kuhl which came with "free installation".

"While minimal kernels cannot prevent every vulnerability, reducing attack surface by removing unnecessary kernel features, drivers, and services can proactively mitigate many classes of security issues and reduce exploitability."

Intro There's something slightly absurd about turning a tiny retro handheld into both an app development platform and a weak-signal radio decoder.

It's a Training Ground for Engineers (And We've Been Ignoring It) Let's drop the nostalgia and say something uncomfortable: If you think ham radio is just people talking into microphones, you're not just wrong - you're overlooking one of the most hands-on,

Initial setup Initially, I had set up a TP-Link ER605 (TL-R605) V2 router to handle the dual WANs - on paper, it checked all the boxes: load balancing, failover, and a relatively affordable price point.

'Rant' Urban EDC used to be about utility; now it's often curated consumption dressed up as identity.

The problem Debian binary packages often require dependency patching, especially when installing on different Linux distributions.

I could NOT get the Open-Source Thermal Simulation of PCBs technique to work with my 4-layer PCB board at all, even after spending some days on it.

Avoid Gazon ISP: A Frustrating Experience for Developers If you're a developer, engineer, or even a moderately technical user, internet reliability is not optional - it's foundational.

Why This Post Exists I wanted to learn practical voltage fault injection on low-cost MCUs like WCH CH32V003 and Puya PY32F003.

We are working on reversing the Huidu HD-R712 LED Display Full Color Receiving Card - a very cost-effective (~1000 INR) and widely available FPGA board.

Polar Modulation for Everyone We have been working on SSB generation using polar modulation.

I recently worked on a redesign of the PA0FRI active antenna using high-speed BFR93A, BFR106, and BFR193 transistors.

Description We have built the simplest, power-efficient and 'ready-for-solar' APRS Digipeater and iGate on an MCU (RPi Pico 2 W)!

Description We have built a Bluetooth-enabled and APRSdroid-compatible digital interface (KISS TNC) for less than 15 USD (for the fully-loaded make including cables).

Design Here is a "safe" APRS interface for BaoFeng and other radios.

Idea Ismo recently shared the https://github.com/CoolNamesAllTaken/adsbee project, which is very interesting.

Ismo (OH2FTG) has praised the STM32's ADC quality multiple times, and I finally decided to give it a go.

Hello, I'm Dhiru.

The PE4312 is a 50Ω, 6-bit RF digital step attenuator available for around 2 USD.

This short article describes a flight-safe power supply for FieldOps.

What This Article Covers This article presents a practical journey to add Linux support for the HOPERF CMT2300A Sub-GHz RF transceiver - starting from extracting register configuration tables out of vendor firmware, to building and testing a Linux driver…

The HFDY Active Loop is working extremely well, even from an indoor location in MK68.

This note demonstrates a small connectivity tester / check nets program for KiCad.

Related articles: Proper Single Transistor LNA for HF A Sustainable Radio Design?

Setup: Si5351 RF generator (@ 28 MHz) ➔ GSD-Hacks-v5 digital amplifier ➔ 7th order LPF ➔ {COAX-UNDER-TEST} ➔ Digital RF power meter ➔ Dummy load Results Results at 13.8V drain: Coax Type Power Reading RG-58 (7 meters) 4.5W RG-316 (7 meters) 3.9W RG-188 (7…

Here is the schematic for a standard 50Ω LPF for the 12-11-10m bands.

Note: This HF LNA design is inspired by PY2OHH designs and mcHF work.

My solar powered WSPR beacon is now active on the 12m band!

Setup OS and SDR Please use the latest Raspberry Pi OS 64-bit on RPi 4 or later.

My old Luminous Zelio inverter (bought in ~2013) lasted for close to 8 years.