brainwagon

I like using my SDR-IQ software defined receiver for listening to short wave and ham bands. It’s a great way to look at a bunch of frequencies all at once, and to isolate the signals you are interested in. I had heard that there were new versions of the SDR-Radio application and Spectravue which I […]

I made a brief mention of this website a few weeks ago on Twitter, but thought I should also archive a link to it here. If you are looking for some nice VHF and/or UHF antennas, these seem pretty neat, with clear directions. They also have the benefit of being stealthy: disguised mostly as flower […]

Okay, it’s been a while since I posted anything: I’ve been busy with travel and the holidays, and now I’m trying to get my home office/shack setup so I can pursue some other projects. It is one of those rooms that has piles of crap, some of which I haven’t seen in years, so I’m […]

Hajos dropped me a quick email to thank me for helping him in his Arduino project that uses an Arduino to monitor tweets using an Ethernet shield, and then translating messages that contain #morse or #cw into Morse code. Glad I could be of some minor help! Hajos Kontrapunkte: MorseTweeter V 0.7 is running.

Some idle musings by hacker Jeri Ellsworth has spawned a contest for designs using the 555 timer. It’s not really my area of expertise (and designs are due by March 1, which doesn’t mesh with my current priorities) but if you have some good 555 ideas, check it out: 555 Contest: Welcome!.

My “on-this-day” blog sidebar indicates that I was looking at Roger, G3XBM’s XBM80-2 transciever: a fiendishly clever low parts count CW transciever for 80m. I’ve been pondering it a bit as something I should just tack together (I think I have all the parts in my junk box) so I’ve been staring at the design […]

Thanks to Roger, G3XBM for the link to PA1B’s QRPp page. QRP operation is operating with an output power of 5w, QRPp operation is operating with output powers down in the mw range. Bert, PA1B has some nice links to this kind of operation, and includes some designs for 20db attenuators that are easy to […]

A few days ago, I created a small program to compute bandpass filters using the equations from Experimental Methods in RF Design. Basically, you can pick a given inductor value, and then it solves for all the necessary capacitors. What wasn’t immediately obvious from the equations and the values that are generated was how these […]

I wanted to log a bunch of APRS-IS traffic for analysis, but didn’t really want to write any code (my brain hurts today), so I tried to figure out what the magic incantation is. It wasn’t necessary for me to inject any new info into the network, so it’s actually pretty easy. Type: ncat -C […]

A long time ago, I wrote some code to send simple morse messages by toggling a pin of an Arduino. It could either blink an LED, or if you wired a bias resistor and transistor to it, you could use it to (say) act like a key for the FT-817. But then I lost the […]

I’ve been thinking about making a kind of “codec2 robot” that people can telnet to and get responses from, and toward that end, I thought I’d see how it did on synthetic speech, since I thought being able to use a speech synthesizer for responses would be good. I had a file generated from my […]

A while ago, I worked up a simple little program that could generate both computer generated speech and Morse code at various speeds to make up some sample recordings I could use to brush up on my Morse skills. I apparently left it in a pretty broken state though: it could use some work. But […]

I had some time yesterday, but no enthusiasm for melting solder (hey, some times, you just don’t feel it) so I thought I’d spend some time, well, learning stuff. So, I dusted off EMRFD and looked at the design equations for creating bandpass filters for receiver inputs. On my second printing, these occur on page […]

Previously, I noted that the oscillator on my DC40B kit (supplied by Doug Hendrick’s qrpkits.com was rather sluggish to start. Reading the messages on the Yahoo! groups, it seems that adding additional capacitance to the Colpitts oscillator was the correct fix, so today, I dug some 47pfs out of my junk box and soldered them […]

I’ve previously mentioned David Rowe’s excellent work on a patent free codec for amateur radio, Codec2, but today is the first time I actually downloaded the code and gave it a shot. You can find the code and the quickstart here: Codec 2 « Rowetel My own voice has some fairly low frequencies in it, […]