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Recently, I was stuck trying to understand how Firebase gRPC calls worked and how I could generate, modify, and replay them. Trapping and modifying existing gRPC traffic was not working well. Finally, I took a step back and spent some time learning how to build and debug simple Firebase applications. This approach helped me tremendously, and I was able to make further progress with my original task quickly. Solution You may find the following code sample useful when reversing/debugging Firebase applications. ...

This is an early design sketch of a 2m WSPR beacon. Key Points 25 MHz HCI 0.5ppm TCXO powering the Si5351 module instead of the 26 MHz TCXO. If this fails, we can use a 10 MHz OCXO instead (a bit out of spec but works fine). Tokmas CID10N65F GaN FET might work @ 144 MHz as the 'final'. If not, use Mitsubishi RD15HVF1-501 MOSFET as backup. 2SK3475 as the driver with variable DC bias at the gate The whole VCC to this amplifier will be PTT switched Ideally, we would want to keep the driver stage linear but the final stage as switched (Class C/D) Alternate: Perhaps by DC coupling the Si5351 input to 2SK3475, we can avoid the need for DC gate bias The "RFC" (bifilar coil still needed?) part will need to be figured out for VHF! Status Results: To be built and tested soon! ...

Here is a quick script to verify that the certificate chain is valid and will work. % cat verify-cert-key.sh #!/usr/bin/env bash certFile="${1}" keyFile="${2}" caFile="${3}" certPubKey="$(openssl x509 -noout -pubkey -in "${certFile}")" keyPubKey="$(openssl pkey -pubout -in "${keyFile}")" if [[ "${certPubKey}" == "${keyPubKey}" ]] then echo "PASS: key and cert match" else echo "FAIL: key and cert DO NOT match" fi openssl verify -CAfile "${3}" "${1}"

Tangara is an excellent project! It recently inspired us to build a similar FOSS DAP product but at a much lower cost of <= 40 USD. Our initial tech stack: RP2350-Zero, PCM5102A 32-bit 384kHz DAC, Burr-Brown OPA1662 (specified for 3.3v) as the unity gain buffer and headphone driver, no explicit DC-DC converters anywhere, microSD card, everything will be a module if possible We quickly got this prototype working on a breadboard and discovered some limitations: ...

This is an early design sketch of a 6m WSPR beacon. Key Points 25 MHz HCI 0.5ppm TCXO powering the Si5351 module instead of the 26 MHz TCXO. If this fails, we can use a 10 MHz OCXO instead (a bit out of spec but works fine). Tokmas CID10N65F GaN FET should work @ 50 MHz TI UCC27614 or Onsemi NCP81074 gate driver Status Results: To be built and tested soon! ...

This ~1W to ~5W WSPR beacon runs continuously on the 10m band. It handles extreme environmental temperatures pretty well (it is 42°C plus here). Our article on this beacon's design and operation will appear in the May/June 2025 issue of the QEX magazine soon. References WSPR TX by G0UPL QEX May-June 2025 TOC ...

Ismo (OH2FTG) recently introduced me to a bunch of Tokmas RF parts. Out of these, the Tokmas CID10N65F GaN FET stood out. It seems to have a lot of potential (for HF + 6m) at a very low price point. This RF MOSFET part can be purchased from LCSC. It seems Tokmas CID10N65F has the potential to completely replace the RD16HHF1 part from Mitsubishi Electric! Datasheet Datasheet excerpt: ...

I have designed, built, and tested an all-HF WSPR beacon that produces 1W @ 5V and is rugged and cost-effective. Results Power consumption: Around 420mA @ 5V. Cost Cost: Around 500 INR. Time to build Time to build: Less than 30 minutes. Files The files for this project are published here for personal (non-commercial) use. For a 5W (QRO) WSPR beacon, please stay tuned for our upcoming QEX magazine article ;) ...

I found this 60W Electronic Load to be quite useful for testing small power adapters and supplies. While it is possible to homebrew an adjustable electronic load we recommend getting this electronic load module or a better-but-costlier one like the UNI-T UTL8212+ electronic load. Observations You can stress-test power supplies using this electronic load quite easily and conveniently. It turns out that the Orange branded 12V 2A or 3A adapters from Robu are of really poor quality. The output voltage drops to less than 2V when the load current is increased to around 1A. This is NOT the first time that the Orange branded stuff has turned out to be of poor quality. In the end, you get what you pay for. ...

Tangara is an excellent project. I found this review of Tangara's design very interesting and educational. It has inspired us to build a similar FOSS DAP product but at a much lower cost of 40 USD (that being the launch price of Sansa Clip in year 2007). The idea is to deliver '90% of the value' of Tangara in a slightly smaller (but fatter) and more cost-effective package. Design Initial tech stack: RP2350-Zero, PCM5102A 32-bit 384kHz DAC, Burr-Brown OPA1662 (specified for 3.3v) as the unity gain buffer and headphone driver, no explicit DC-DC converters anywhere, microSD card, everything will be a module if possible ...