SDR K0AWU
- SoftRock Ver9 Software defined receiver
V9 with 30-17m coil set. This receiver covers 160-10m. The center frequencies are determined by a USB controlled Si570 much like the V6.3RxTx.
The V9 with Softrock 2 meter converter "stack". This converter was designed by the QRP2000 Design team. The design is a novel 144 MHz Dual conversion SDR Receiver which only requires a single Si570 as Local Oscillator.
November 14, 2008 --- The V9 receiver and Softrock 2 meter converter were completed this past week and I applied power to the combination for the first time today. This is a "beta" converter, so the main purpose of the build was to determine performance. The build was straight forward and alignment was easy with the weak signal source in the yard.
The first tests were conducted by looking at different converter / preamp combinations to see how a less than $40 2meter SDR receiver was going to stack up against the current station. The converter uses a BF991 front end followed by a Mini-Circuits ADE1 balance mixer. The BF991 is a dual gate MOSFET with a noise figure of less than one, so a good "start". In tests by others, the system shows better 120dBm sensitivity for 10dB Sinad in 2.4 kHz SSB BW.
I have no real way to evaluate other that what measurements I can make with a signal source and Rocky for signal level in db. My initial observations are that when used with my ARR 1302 based preamp, this combination is within 2db of my best receiving system. Used without a preamp, it would be very usable for local communications. The preamp improved signal recovery by almost 10db.
Jan 24,2008 Switchable BPF UPDATE
I have now built the switchable BPF filter board and have it setup. No question it is less of a hassle to switch bands. The filtering is now better so the problems with 10mhz shortwave images are greatly reduced on 75meters. The filter switching is not possible with Rocky, so I have switched to the latest version of PowerSDR (1.16.1), this with the Sdr1kUSB.dll from NSLU2 webserver (http://212.254.198.33/bpf_usb/. Only a 2 conductor jumper from J3 on the V9 to J1/J2 on the BPF board is required.
