VE9QRP

 End-fed halfwave antennas are so convenient, especially in rapidly deployed setups, and they're easy to build . But how much energy is lost in the 49:1 transformer that makes it possible? Because I operate mainly QRP, and I'm using a rather large core for 5w, I'm not concerned with losses that appear once the transformer's core reaches the Curie temperature. So I can use a nanoVNA, performing a S21 logmag trace on two cores back-to-back, to see how much power my transformer is eating up on the way to the antenna. I used the Fair-Rite 2643625002 core, inspired by excellent results MM0OPX reports in a generously shared spreadsheet of results. Could I get around 0.5 dB loss from 80m all the way to 10m if I used that core in 21:3 turns ratio?  My experience with more donut-shaped ones suggested that such broad-banded performance was a tough order: a 14:2 turns ratio works well on one end of the HF band; 21:3 works well on the other. In the end, Colin's accompanying vi...

These live discussion sessions with N2APB and N2CX are an absolute goldmine of information about HF design for the amateur. There's a good mix of analog and DSP. My only gripe is that there doesn't appear to be a podcast feed, so I had to set up a 'virtual' feed in Doggcatcher so that it would queue these.

I've often peeked at http://www.reversebeacon.net/ , the Reverse Beacon network that uses a network of observers equipped with CWSkimmer to list the heard stations that are calling CQ on CW. If you can find an observer near you, it gives a pretty interesting view of propagation. During the IntDX competition this past weekend, I thought I might have been picked up, but as a QRP station, I didn't do any CQ'ing during this contest; consequently, I didn't get added to the mix. So this morning I tested the network: I made a single CQ on a pretty dead 15m, by hand. Sure enough, I was picked up by the K4TD skimmer! This is nifty in two ways. First, I think the RBN shows how CW continues to have strengths as a mode. It is digital enough that current computing technology can parse it (and, of course, create it); but it is a digital mode that was created for human production and decoding, so we don't have to have a computer in the middle to play with it. Second, and mo...

The QSO with Paul, ZL3IN, has garnered quite a bit of attention, with very positive reviews of the state of Codec2 and the spirit of David's project in general. Amateur Radio Newsline gave Paul and me some of their airtime . The ÖVSV (Austrian Amateur Radio League) reported on us, as did Southgate ARC's excellent site . Report #4 of 2011 of the BB-Amateurfunkmagazins put us at the top of their issue, in a piece entitled "Video zeigt quelloffenen Sprachcodec in der Praxis". The Interessengemeinschaft Amateurfunk Osnabrück notes that "Das Beispiel zeigt jedoch, was heute möglich ist und dass man trotz äußerst geringer Bandbreite akzeptabel Sprache übertragen kann." And finally, KC4BQK says, "This is what I think Amateur radio is all about ."

I'm tiring of using a terminal to put my Kenwood radios' TNCs into kiss mode. Here's a oneliner in python that will do the same thing. Why Python? My experience with Ruby and the satpack code was that its serial library was hard to get going on windows. This should be more portable, and get the job done: python -c 'import serial;ser=serial.Serial("/dev/ttyUSB0", 9600, timeout=1);ser.write("kiss on\r\n");print ser.readlines();ser.write("restart\r\n");print ser.readlines();' It should reply something like this: ['kiss on\r\n', 'KISS was OFF\r\n', 'cmd:'] ['r']

Here's the video of the ZL3IN c2qso.sh contact. Remember, this is just raw UDP packets over the internet, with no error correction, and you're hearing the Codec2 audio just as it was transmitted in the conversation.

Over the weekend I had a half-hour conversation with Paul, ZL3IN, using Codec2. Paul corrected an error in the script I've published, and we were thus able to hear each other. His side of the conversation encoded in Codec2 is available here ; you can get my side here . I've also mixed the two into a wav file . Details and a video will follow.