----- Original Message ----- From: "drmail377"> I scrounged two 600 Ohm isolation > transformers from a couple of old dial-up modem cards I had in a junk > box and put them between the radio and the sound card inputs. I think > the source of the problem stems from the fact that there were two > grounds connected to the radio, one from the power supply and one from > the PC.
It should be possible to get good results without isolation. Just use one ground, break others, test which ground gives the best result. I usually find that just connecting the audio shield gives an almost perfect waterfall. The one thing to watch is that the power may return via this ground so the advice always given to switch off before making or breaking connections could be important, although my D44s are still functioning! Back in the old days of valve (tube) amplifiers ground loops were commonly apparent, usually cured by careful grounding rather than using isolation. In those days transformers were big and expensive and likely to get hum pickup from other transformers (as they can today!). >The antenna ground was isolated. Speaking of antenna grounds... > > You might also want to make sure your antenna ground is isolated from > any other ground. The antenna should be grounded, just make sure the ground does not go to the Softrock ground, (as you say, insulated socket) that's where the ground loop is. 73 Alan G4ZFQ
