1750Hz tone generator

Dilshan Jayakody published a new build: The 1750Hz tone bursts are often used to trigger repeaters. There are several methods to build 1750Hz tone generators which including TC5082 divider, using MCUs, etc. In this post, I present another 1750Hz tone generator which I built using 74HC4060 high-speed 14-stage binary ripple counter and 7.168MHz crystal. In […]

Automated channel switching with Motorola GM3x0

Florian Wolters wrote an article on automated channel switching for POCSAG/DAPNET transmissions on MMDVM system: With the integration of POCSAG/DAPNET features into the MMDVM/MMDVMHost I came to think about if it would be possible to combine an MMDVM repeater/HotSpot with a DAPNET tranmitter. The advantage in Germany is that there is a single coordinated frequency […]

SI5351 VFO project

Dave Richards (a.k.a. AA7EE) has a nice write-up about building another Si5351 VFO project: To many, this will be just another Si5351 VFO project, with nothing to distinguish it from the others. In fact, that’s exactly what it is. The “how to” of connecting an Arduino board to an Si5351 board, wiring up a display, […]

RX/TX sequencer

Lukas Fässler has designed and built an RX/TX sequencer based on a PIC16F18325,  that is available on github: Much like the beacon keyer presented here earlier, this RX/TX sequencer is a simple but useful little device. Its typical use is in ham radio applications when a separate power amplifier (PA) and/or a sensitive low-noise pre-amplifier (LNA) is used. […]

Beacon Keyer

Lukas Fässler from Soldernerd published a project writeup showing how he built a PIC-based beacon keyer: This is likely the first ham radio related project that I document here on this blog But my very first PIC project was a beacon keyer that I made for my father, HB9BBD. That was in 2013. A beacon […]

Homebrew 40dB step attenuator

flathagen blogged about his step attenuator build: A home lab needs a step attenuator. It helps in evaluating RF amplifiers, filters and receivers. Both the legendary EMRFD-book, the ARRL handbook, and a variety of QST-articles provides circuit examples for building a homebrew device. Most of them follow the design principles from the January 1967 edition […]

EMRFD Direct conversion 40m receiver in a tea caddy

Flathagen has made a DIY EMRFD Direct conversion 40m receiver in a tea caddy: I woke up one day eager to build something simple (at least I thought is was simple) and opened up the first chapter in EMRFD and decided to build the 40m direct conversion receiver. I already had most of the components in […]

Embedded Linux APRS iGate tutorial

A detailed tutorial on how to make your own APRS iGate (Automatic Packet Reporting System)  from Andrew Milluzzi: With the super cheap embedded Linux platforms (Raspi, Beaglebone, etc.) and cheap TV dongles, it is really easy to make your own APRS iGate, just like the one in the photo above. This tutorial will give you […]

Audible Morse code to text message converter

Dilshan Jayakody writes: Morse View is an open source software project to convert audible Morse codes to text messages. This application is capable to convert Morse codes from wave files or from the audio line/microphone inputs. Conversion from Morse code to text can perform based on amplitude and frequency decomposition of the input audio stream. […]

Amateur radio study guide has much information about electronics

Ham radio is nothing new, however if your new to electronics, or interested  in becoming a ham, we suggest reading one of Dan’s self-study guides. The RMS value of an AC signal is the voltage that causes the same power dissipation as a DC voltage of the same value. (G5B07) For an AC signal with […]