[Lowfer] Hi-pot testing of pipe cap and THHN house wire today...

[WE0H]

I tried to fry my new copper pipe variable cap today at work. I couldn't get
it to fail. I applied 4500vac and 5000vdc to the cap and nothing happened.

I then took a foot of #12 THHN house wire and laid it on a sheet of aluminum
which had the hi-pot tester connected to the stripped end of the wire and
the other connection to the metal sheet. I slowly ran the DC volts to 5000
and nothing arced at all. I then applied AC volts to it and found at 2500vac
that the wire started to make a frying sound and emitted ozone. I continued
to 4500vac and the sound got louder and smelled more ozone, but no arcs were
seen in a dark room and the insulation didn't show any damage.

I have come to the conclusion that the loop wire lying on the tree branches
should not have any trouble with voltage levels as I tested. The trees even
wet with rain wouldn't have the conductivity of the metal sheet.

It appears that the transmit loops will work fine with higher power when we
get 136kc and for use under the Part-5 400w limit.

I should note that the cap has several layers of 6-mil poly wrapped around
the inner pipe and measures 173pf with a minimum value of 13pf. It is quite
compact. I should have pictures when it is finished.

I hope I haven't overlooked something here, as I am no engineer.

73's,
Mike>WE0H
http://www.we0h.us/lf.html