For a recent experiment I was using BA389 PIN diodes to switch low power RF signals. I was asked why I didn't use an ordinary 1N4148 for that. Since I didn't know what an 1N4148 would do when used like that, and I also didn't really know what a BA389 actually does, I decided to do some measurements.Aren't diodes …

Building a receiver for a voice repeater system in this area I set up a thumbsat receiver connected to a Raspberry Pi. The receiver is part of the repeater system to widen it's receiving range. However, the performance turned out not to be too optimal. I guessed that the GSM and Wifi signals around here could cause the …

Users of Mattermost have probably noticed the less-than-optimal interface design where de Delete option is right above the Leave option in the Channel menu. On a busy server, you can imagine having quite a few incidents where people accidentally completely delete a channel. In the Open Source version of Mattermost, …

[caption id="attachment_2130" align="aligncenter" width="450"]WiFi Serial Transceiver Module Breakout Board w& ESP8266 pinout[/caption] This is the pinout for the Seeed WiFi ESP8266 breakout board. Please be careful, it only accepts 3.3 Volt nominal input voltage and logic. Putting 5 …

Many years ago, I used to do some radio fox hunting with cars. Usually these hunts are at night to make it more exciting, and can be great fun. As I got older I lost interest and moved on to other things. But last year, I decided to have a go at a popular balloon fox hunt on 144MHz. This is quite a large scale and …

Ever wondered how well your 50Ω coaxial cable is working? If you have a reasonably fast oscilloscope, preferably up to 100MHz and a signal generator which can generate short bursts, you can measure not only the length of your cable, but also the return loss at a certain frequency. From that, we can learn the …

Undoubtedly the Baofeng UV-5Rx delivers a lot of radio for your buck. However some models in the range have a bad reputation for the transmitted audio sounding soft and muffled. In 2013, Remco PA3FYM obtained the schematics of the radio and devised a modification where transistor Q17 of the VOX is re-purposed as …

For some reason I have trouble finding a document which lists the complete IARU Region 1 Band Plans. To end my "can I transmit here" quests, I've combined the information from several resources into a usable graphical representation of all Amateur Radio bands and modes up to 500MHz. I've not listed bands …