Monday, November 22, 2010

Simple signal generator

With a little bit of inspiration from the blog of M0XPD I have built a simple signal generator. The original design is from NorCal QRP club and can be found here. I´m able to create a S1 or S9 signal (more about the s level here) that I can listen to if I´m going to test a receiver. I can change between 4 different crystals/frequencies. As there is no low pass filtering in the circuit there will also be harmonics. Here is two pictures and you can see that it´s been a while since I built it but haven´t documented it until now.

The box by the way is bought at IKEA. I think it was 7 different boxes in one set and quite cheap. Next test equipment in the blog will use one from that set too.

Sunday, November 21, 2010

Linux and LTspice

I finally changed over (or should I say back) my main desktop to Linux. This time it is 64 bit Ubuntu 10.10. I have been running Linux for the last 15 years or so, but changed to Windows some year ago and one of the reasons was that the SDR software I wanted to use was only available for Windows. But now I felt it was time to go back. I have not run Ubuntu earlier, previously it has been Slackware, Debian and OpenSuse (in that order in time), but I can only say that I am impressed with Ubuntu today. Everything worked "out of the box". No fiddling with drivers as it has been in the past.

This Saturday I attended a meeting in the ham club with the topic LTspice. If you have not heard about it earlier, it is a software that can simulate circuits. A very good tool I think. The introduction was held by Volker SM5ZBS. You can check out his homepage. It is in German but I think it is interesting and can be translated if needed. On the screen above you see my new Ubuntu desktop and LTspice which is a Microsoft Windows software is running. You may ask how that works? It is running in Wine, a tool in Linux that makes it possible for some Windows software to run in Linux. Works great!

By the way, the circuit that I have laid out is a audio filter I found in chapter 15 in the book CRYSTAL SETS TO SIDEBAND by Frank W. Harris, KØIYE. It a free download as everything I mentioned in this post!

Monday, November 15, 2010

20m antenna and remote listening

I´ve been having some fun during last couple of days. I live in an apartment where I don't have that much of space for antennas and regular radio activity. But at a relatives house where a lot of trees is available I´ve been playing around a bit. I have been here some year ago and at that time I was laying out BOGs (Beverage on ground) antennas and I was DXing for AM stations in South America, but this time I wanted to focus on the amateur radio bands and in this case the 20m band. One easy antenna to build is a vertical using stubs to get a good match that I learnt about from SE5X. The radiator element was around 10 meters that I throw up in a tree.

If you would like to build this antenna, this PDF from SM0JZT describes the lengths of each segment. It´s in Swedish but I think you will understand if you are interested. Otherwise let me know via the comments.

When everything was installed last Monday it had went dark so 20m started to close and I never got a QSO. Instead I setup the QS1R and prepared for remote listening via LogMeIn Pro.

Below is a capture taken on my home computer. I have connected to the LogMeIn server via the web browser so this is the experience I got. The connection is a quite slow ADSL so I set the update rate of the waterfall to a slow setting. As this was done late when 20m was dead, this is 40m.

I went back on Thursday lunch last week and had one QSO with M3GFQ on 20m. I got 59 and I think that was a true report. :-)

Hopefully soon the new software for QS1R will be available. This will make it possible to run the server part remote and the GUI at home and be able to record RF to disk. I actually don´t feel so good about paying for this remote solution from LogMeIn, but as this opportunity to have the remote QS1R came up and I didn´t have time to setup streaming audio (open ports in firewall etc.) the Logmein solution is really working well. With new QS1R software I can hopefully use Linux instead of Windows. Remote QTH saga will continue...