StrikeFinder Problem

I had an Insight StrikeFinder installed several years ago, and it always
worked well, detecting nearly zero electrical interference from the
aircraft in flight. The StrikeFinder is on a push-pull breaker, and
over the winter I normally kept it unpowered, primarily because I didn't
need it, but also because of concerns with the life of the gas plasma
display (Insight has since told me that not powering the unit could be
worse for the display than having it lit continuously.)

In any case, I've now started to power the unit in flight again, and it
is painting a solid line directly off the nose of the aircraft almost
immediately. Clear the display, and the line comes back within a minute
or two.

About 6 months ago, I had my alternator replaced with an overhauled unit
to cure alternator whine through the audio system, and that plan mostly
worked. This is the only change to the electrical system that I've
made, and given the location of the noise the StrikeFinder is painting,
I'm guessing that's the problem. During the alternator replacement,
there was a new grounding strap fabricated and applied between the
alternator and the engine. The alternator has a new filter cap on the
output, shunted to ground on the alternator case. As a mentioned, this
alternator basically cleaned up the audible whine that I had with my
previous unit, which did not cause electrical interference with the
StrikeFinder (but did produce an annoying whine in the audio system).

Insight is telling me that the only solution to my problem, if it is the
alternator, is to replace the alternator. Needless to say, I don't want
to keep swapping alternators endlessly. Does anyone have any experience
or suggestions?


Thanks,
JKG