You have my thanks. Using testmy.net I have been able to isolate recurring problems with my Internet connection. This was something I could not accomplish using the more common FLASH based Internet speed test tools that are so commonly used.
I imagine there may be other small issues but the big problem of inconsistency was identified as a cable splice adding a couple feet of coax cable on the end of the line drop to my house. As I had reported, the splice was left exposed to the environment and when weather conditions were poor (wind and rain), my connections suffered with a 15 - 40% degradation. I applied a temporary weather proofing over the spliced area and today, with wind a rain, I have been able to maintain a consistent D/L speed.
Again, thank you. This is a good and useful tool.