"Star" construction continues.
Here it is almost a year since I first started on this and things haven't changed much. I'm back to working on the rig after making some decisions on which way it's going. So far I have the DSP and IF boards fully stuffed. The DSP unit seems to work as I can download the firmware it passes the audio loop back test and sounds the "HI" greeting in Morse code. The IF board needs to be 'smoke' tested and verified. Hopefully it will function and won't need major debugging.
DSP motherboard and Processor board
Here are the 'stuffed' DSP mother and processor boards
Populated IF board and DSP assembly with all three pcb's
Above you see my fully populated IF board assembly ready for the DSP to be mounted underneath. The DSP board now has the codec board mounted and is wired up for testing. I've made some part substitutions in the IF board to make use of what I have. The IF gain adjustment pots are 20 turn units I had a ton of. the 330uh RF choke was replaced with one wound on a toroid. I didn't have the required feed-through caps that go through the board to the DSP unit so I used some nylon bushings as insulators and used radial lead caps on both sides of the board. A few of the fixed resistors were replaced with trimmers to make alignment easier later. Both boards have tarnished since their construction was drawn out over time and they were never spray lacquered. Still I've had no problems soldering them and at least they haven't turned green! (Copper oxidation is usually surface only unlike iron which will rust through to the core. Ask Miss. Liberty.)
I'm using the surplus CB 10.7mhz filter that many builders have used. Mine came from www.rfparts.com. I have a bunch of surplus 9mhz 3.1khz wide filters designed for the ancient Gonset Sidewinder VHF rig that I picked up at Dayton years ago. While I think those filters might have had some advantages they were quite a bit larger and would have required some modifications to the IF board to use.
I'm using the surplus CB 10.7mhz filter that many builders have used. Mine came from www.rfparts.com. I have a bunch of surplus 9mhz 3.1khz wide filters designed for the ancient Gonset Sidewinder VHF rig that I picked up at Dayton years ago. While I think those filters might have had some advantages they were quite a bit larger and would have required some modifications to the IF board to use.