Exploring SDR

The nicest thing (at least I think it is) about our hobby are the many different aspects. If you seen enough of one, you can put this activity on hold and switch to another. A few months ago a conversation on 40 meters raised my interest in SDR (Software Defined Radio). Instead of using a rig with internal firmware, SDR is a more physical separation between hard- and software. You buy and build a kit, download some software and of you go! You can also buy ready-build kits. It was the general mentioning in the conversations that talked about very clean signals and the visibility of them on a computerscreen that awoke my interest. Second was the building of the kit. I'm not very experienced in selfbuilding and soldering, perhaps this was the oppertunity to make a good start!

While gathering information about this subject on the internet, I came accros the site of the Harzburg II kit. While focussing in on this 3-30 MHz 'Fernempfangsradio', many others pages showed up. One of them showed the ease of constructing this kit, so my confidence of building this was set. I ordered the kit, and start reading everything in order to prepare myself. The kit arrived in a couple of days, and when there was some spare time left I took the soldering iron in one hand and the construction manual in the other. It was with with great ease that a beginner like me was able to finalize this part of the project and as you'll understand it gave me lots of fun. After checking (and doublechecking) the board and its components, the moment of reward came in sight.

There are different programs to use, some of them are free to download on the Internet. First priority was checking if the board was functional, software topics will follow in a later stage. For a start I decided to make use of SDR-RADIO.com by HB9DRV, the same amateur who gave us Hamradio Deluxe. After hooking up the board on my little netbook by RS232/USB and an audio cable, I connected my multiband wire-antenna on the BNC connector. The kit also needs 13,8 volts. If everything is in order and a red led on the board is glowing, starting the software is the next step. Like all ham programs which talks to hardware, this program also needs some configuration. After telling the program which comport to use and which soundcard, the magic begins!


You'll understand the moment of joy and satisfaction when the board came alive and on the screen a beautifull diorama of a frequency spectrum showed up! On 20 meters, my favourite band, I saw several signals that were inviting me to click in order to focus in on them. Choosing one results in receiving that signal, and then there are lots of functions to fine-tune and filter them. Some signals are indeed very clean, although I'm not experienced enough to make a compare with my Yeasu FT-950. Also the propagations wern't very good, so I have to use it more often to make a good evaluation. I also want to make use of other SDR programs, for instance HDSDR (formerly known as WinRad). There is also a modification that expands receiving 160 meters on the agenda.