Ron H wrote:
Can I use some RG-58/9 coax as a conductor for a fencer? The unit pulses
about once per second at about 2500 volts. I need to feed a fence with about
25 feet of conductor underground so I thought maybe using the coax leaving
the shield ungrounded might work. Any thoughts? I figured that if I grounded
the shield, it might act as a choke......

At this sort of frequency, the shield acts mostly like a bit of
capacitance. And that doesn't vary much whether you ground it or not,
once the cable is buried, since the soil surrounding the cable is also
"grounded". But leaving it floating makes it a shock hazard. I would
ground it. I also suggest that you strip the shield back a couple
inches from the ends of the internal insulation, to keep the center
wire from arching to the shield at the ends.