The SoftRock Lite II SDR has been a lot of fun to play with. As shipped and built for the 20 meter band, it tunes across a good portion of the CW and data portion of the band. I was delighted to learn that the Dell Precision M6500 I’m using for this has a high end sound system in it. This gave me the ability to receive a larger portion of the band than Josh could with his sound card. The software I’ve been using is Quisk (on Linux of course).
I purchased an AD9850 DDS board on ebay for a whopping $5 or so (incl shipping from China). After a little research I wired that up to the Arduino and wrote a simple sketch that generated a single frequency from the DDS. My goal is to replace the crystal oscillator on the SDR with the DDS. This would allow me to tune the upper part of the band as I’m interested in SSB and SSTV. I did find that a direct connection didn’t work so I wired up a quick two transistor buffer amp. Now it almost seems like I have too much gain on it.
That’s where I’ve left things for the moment. I’ve got enough parts to start building the BITX radio so that will likely consume most of my hobby time for a while. I’m also gathering parts for another Arduino project to measure and record temperature from a number of points (long story). So many distractions. I really need to get in and clean the garage, set up a proper workbench.
I have a softrock lite II arriving here shortly. I’m not a lisenced HAM (yet!), and I found this SDR receiver a great way to affordably get my feet wet and motivate me to learn more. I really don’t want to build this RF front-end device to center on the lower band of 20m as this would primarily be morse code and data transfers. I would like it to center on the SSB side of 20m. Are there any links/info to instruct how to modify components to center the device at say 14.25MHz? I have a feeling my options are going to be limited by the availability of crystal oscillators.
I’m playing with a DDS based on the AD9850 and controlled with an Arduino. That’s something of an advanced solution and maybe overkill (like using a nuke to kill a fly).
You can easily move the center frequency by changing the crystal. I don’t think you would need to change anything else at all. You should be able to find a used crystal somewhere that is close. Worst case would be you order a new crystal cut to the frequency you want. If memory serves I think you’re looking for something very close to 19.00 MHz.