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1. Power Supply. I printed a few pages of the Genesis assembly info (#1 above) and completed the build. I could have used the info on theWB5RVZ site - it would have been easier. As if my workbench isn't crowed enough, I should have my MacBook Pro there too?
2. Local Oscillator. Start this time with my printed plus the WB5RVZ local oscillator page on the MBP. Using the computer instead of paper drawings worked okay, but I'd rather flip pages than scroll up and down to see what I'm about to build. At this point, I have the chokes and resistors in.
Here's the oscillator top left, then an overview, and finally the power supply top right. Hard to see the parts with the intense red board.
I've always made a point of designing for testability, and it appears that this product is constructed for easy testing during the build. Here's the completed local oscillator, the test connections, and my scope/counter (not really necessary at the moment). The power and other connections are just heavy wires I put into the proper holes in the circuit board; they're not soldered.
3. Band Switch. The description in the Genesis assembly info (#1) describes a 4-LED display with 2 mini-toggle switches. The better solution, a simple rotary switch, is described near the end of the WB5RVZ band switch page. 3-pin and 2-pin polarized ramp headers at JP1 and JP2 make for quick disconnect of the switch and wires during construction. Wires soldered into the PCB always break off during the build or later servicing, and should be avoided.
AllElectronics had the bandswitch (RS-260) and pre-made connector sets (CON-242, 243) that I used for the bandswitch assembly. I used smaller ribbon wire with standard Molex KK-series ramp connectors for the 23/46 dB toggle switch. FWIW, the switch connection information is correct, but IC5 on the schematic has incorrect pin numbers. The 100 uF capacitor is on the bottom because the rotary switch interferes with it when the front panel is assembled. It all just barely squeeks together now.
4. Dividers. This circuit generates the 4 quadrature oscillator signals, and the docs are at WB5RVZ as usual. Was it the 8008 or 8080 that needed a multiphase clock?
5. Rx Mixers, OpAmps. The divider output connects to this mixer stage. See WB5RVZ for the discussion. The link to Dan Tayloe's paper on the quadrature product detector is particularly interesting. The build was straightforward enough, but you do need to watch for the four non-polarized electrolytics and install in their proper locations.
The image adjustment at the end of this section appeared simple enough on the surface. The idea is to run the stereo I and Q outputs (the single jack on the far right) into the PC's soundcard. Run PowerSDR and make the adjustments. Not so easy: the shop PC runs Windows 2000, and I needed to update the dot-NET 1.1 to a newer service pack. Found that at the FlexRadio site by searching for PowerSDR 1.x, keyword NET. Then, I couldn't find the right version PowerSDR; finally I downloaded the FlexRadio PowerSDR SR-40 version 1.9.0 from the SoftRock-40site. That's the same version as on the MacBook Pro.
Clearly, this first venture into using an SDR was a challenge. I set the frequency to 10.125 and turned on to listen. There was a noise peak about 10 kHz below 10.125 (how'd that happen?) When I applied power to the Genesis and turned on the signal source, I could hear a tone. Fine, but not at the right spot. First, I changed the "setup" to "Soft Rock 40" and Fixed XO to 10.125; next, under audio setup, I changed to 48,000 sample rate. Then my display made sense and I could successfully minimize the image.
Is anything new ever easy? The image was on the wrong side of the display. The simple fix is to swap the I and Q outputs. Because both the shop PC and my MBP both seem to be "wrong," I can swap the wires to the G3020 switches, rather than rewire audio cables. Simpler, I should be able to swap using the software setup, but PowerSDR did not have that feature.
Goran had the answer on the Genesis Yahoo Group: I should download GenesisSDR from http://genesisradio.com.au/GSDR/new/. The install zip file needs to be unzipped and run in its own directory. The latest update file (GSDR_update_06042011.zip) should be extracted to the samedirectory, overwriting older files.
When reviewing the Phase 5 construction details on http://genesisradio.com.au/G3020/a1.html, I saw that Winrad was suggested for testing, so I downloaded the latest version Winrad 1.61. Winrad and GenesisSDR both provide for software swapping I&Q audio inputs.
6. LP Filters and Preamp. For this phase, I printed the WB5RVZ instructions ... for me, I find that the printed pages work out much better at the workbench. The listening test seemed a little cleaner with the front-end LPF.
So far, it appears that the tuning range I have with the MacBook Pro (with iMic USB plugin) is about 14 kHz. The Mac Pro seems to come in with about 38 kHz spread (ie, on 30 meters I can tune from 10.106 MHz to about 10.144 MHz). The idea is to have a great sound card; I haven't addressed this issue yet.
The wires from the bottom of the board go to the amplify/attenuate switch. There's no place to mount a ramp-header connector, so it looks like this is the solution. Maybe something different will come up as the build continues.
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Genesis G3020 SDR 