[petek]

Jack,
Try the ground first (although I do have a separate ground to my sender already...)

I doubt that you'd need much capacitance at all as I'm guessing the noise is actually up in the 100's or perhaps 1000's Hz range. It's just that the meter isn't damped so the meter is capable of sensing the jumps from the sender. (Again, a guess on my part as I haven't taken the meter apart.) For a quick SWAG, try a 10uf, 50 V cap from ground to the sensor lead.

DV... haven't forgotten about you... give me a few minutes... picture coming...