After several days of working on the Softrock RX-TX kit, I have completed the receiver section of the radio kit. Initially did this did not go well. When I plugged in the rig for testing, I was getting a large ac hum right in the middle of the SDR display. I was receiving signals, but they were very weak. After changing cables and trying several SDR programs, I continued to get weak signals. Since I am using a not so fantastic antenna for 20M, I thought that was the best this radio would do, and I would just have to tune around the hum. I went back over the the receiver section several times checking my work and could not find anything obviously wrong. After a couple of days, I decided to give it one last look. I suspected the problem could be in the op amp section. Under closer inspection under the giant magnifying glass, I saw a couple of pins on the op amp chip that looked a little suspicious. Often with these small ICs, the pins look like they may be soldered to the board, but they may not be making a good connection. After I re-soldered the suspect pins, the ac hum went away and the receiver came alive with strong signals! Actually, the Ensemble RX TX does a very nice job as a SDR receiver when you consider its a $74 kit. The Rx TX appears it would hold its own against receivers costing more. That is the beauty of using SDR technology is that you get a lot of high end signal processing out of the SDR software, allowing inexpensive radio hardware perform at a much higher level. Of course there are still a lot of arguments against SDR, you probably have heard most of them. But hey, it’s darn nice to see a large chunk of the amateur radio band at once in the waterfall display, if you have a audio card capable of a 192kHz sampling rate. Even the standard 48kHz sampling rate can be pretty impressive. Another thing that is impressive is the audio quality from the RX TX Ensemble. Coupled with a good set of computer speakers AM shortwave broadcast are excellent. So, for the $74 dollars and a little time, you get a neat little receiver.
Well, on to building the transmitter section. I will try to pay closer attention to my soldering skills this time.
For what it’s worth, below are some links to some inexpensive tools, I have found to be invaluable to building this kit.