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 RTL2832U to overload, so I decided to build an intedigital bandpassfilter using Ajarn Changpuak‘s excelent interdigital bandpass filter calculator.
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 Volts on any of the pins may permanently damage the chip.
The ESP8266 on this board is programmed to do serial communications at 115.2 kilobaud, and accepts AT commands.
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 professionally organized fox hunt by Dutch Radio Amateurs. Read the rest of this entry »
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 attenuation of the cable.
This blog post describes the classic time domain reflection measurement using the following setup:
In 2013, Remco PA3FYM obtained the schematics of the radio and devised a modification where transistor Q17 of the VOX is re-purposed as preamplifier in the microphone audio circuit. It works wonders for your radio. For people needing a bit more visual guidance, below is a walktrough of how I did this to my Baofeng UV-5RA.
I went through all the struggles everybody else seems to be going through to get this screen connected to my Arduino Nano. I had the 5V to 3.3V voltage conversion problem, and the “only works with software interrupts” problem which makes the display run slow. The solutions are not complicated but not very wel documented. Until now.
Not everybody understands why I am trying to learn morse code on lcwo.net. Maybe I’m not even sure myself. But most people seem to think morse code is absolutely dead. I could tell you that’s not the case, but it is far better to find out for yourself. To be able to do that you need access to a radio which can receive CW (continuous wave) signals somewhere between 8MHz and 15MHz. This is the place where HAM Radio Operators hang out and try to talk to eachother. Morse code is still used there, mainly for DX-ing.
So how do you do that? With the power of the internet and a few very enthusiastic people in Dwingeloo, you can now receive radio signals right on your computer using radios all over the world. Lots of links in this article, have fun!