Thanks to all who steered me towards the "bad" ground wiring.
I dug a little deeper and found an old official Harvard Radio cable (that
came with the used made-in-USA back-up DVP card I bought) and a schematic.
I compared the "new" official Harvard cable to the "old" schematic. Not the
same in the grounding. I haven't figured out what exactly is different.
Need to find the "new" schematic, too. Maybe LZ sent me a "bad" cable or
maybe the design has changed and is now "bad". Anyway, when I hooked up the
older cable, the hum went away. I stopped troubleshooting and started
getting ready for ARRL DX and put the station back together.
I had intentions of trying a newly purchased Radio Shack audio xfmr. Glad I
didn't have to experiment at that point in time.
73
Mike
n2mg@contesting.com
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