RE: secondary grounding terminal

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-compaq-dot-com>

I think there is a widespread mistaken notion that the secondary base
connection needs to be super-beefy, perhaps due in part to the widely
read texts written by Richard Quick.  Richard suggested using a large
copper plate with the ground wire held in place with a rubber band.  A
copper plate will quickly develop a resistive oxide coating, and the
integrity of a wire connection provided by a rubber band sounds poor.

The RMS secondary base current of a modest NST-powered coil is only a
fraction of an Amp.  Terry measured 350mA RMS for his 15/60-powered
coil.  The goal of the secondary connection is to provide a low
resistance, low inductance path from the base to RF ground.  The
resistance contributed by any reasonable base connection is negligible
when compared with the total path.  So it won't matter if you use
silver-plated battery connectors or Fahnstock (sp?) clips, as long as
the basic connection is sound.

The ground conductor itself is another matter, given that it may be tens
of feet long.  The AC resistance (i.e. skin effect) of small conductors
becomes significant over long distances, and this is why relatively
beefy conductors are recommended.  But for any 2 mm segment of the
ground path, it won't matter what you use.

One further consideration that I never hear mentioned is that the base
connection should be physically low-profile, in that it doesn't protrude
and become a feature that promotes corona or arcing from the nearby
inner primary turn.

My technique is to wire the secondary base to a press-fit threaded
insert in the center of the base end cap.  This also serves to secure
the secondary assembly to the coil base, although this may be more
elaborate than some may care for.  See 
http://people.ne.mediaone-dot-net/lau/tesla/secondary.htm

Regards, Gary Lau
MA, USA