Re: What gets connected to RF ground?

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

Original poster: "Zagarus Rashkae by way of Terry Fritz <teslalist-at-qwest-dot-net>" <arbitrarily_random-at-yahoo-dot-com>


--- Tesla list <tesla-at-pupman-dot-com> wrote:
 > Original poster: "Jeremy D. Gassmann by way of Terry
 > Fritz <teslalist-at-qwest-dot-net>" <gassmajd-at-email.uc.edu>
 >
 > Group,
 >          I have been doing research on grounding and
 > what you ground to
 > what (ie RF ground and mains ground) and I have
 > found some conflicting
 > advice.  On a number of web sites, the
 > recommendation is to ground the
 > bottom of the secondary as well as the center tap of
 > the NST, and the
 > center ground of the safety gap and filter
 > capacitor.

The RF ground would be rather noisy with its
connection to the TC secondary, I think.

   Another site says
 > that only the secondary gets the ground and the NST
 > and safety gap and
 > filter get house ground.

This is what I do. Ground the center of the xmfr to
house ground, and the TC sec gets the RF ground.

   Another variation of the
 > latter is the you leave
 > the NST center tap ungrounded.

BAD IDEA. The NST can be unbalanced and you want each
side outputting as equal voltage as possible. Also the
center ground gives the NST a reference, otherwise the
core may be hot.

   Still another
 > different variation that goes
 > along with the former is as follows:
 >
 > *snip*
 >
 >          You ground your variac housing to your
 > neutral wire. All other
 > coil controls, relay housings, control xfrmr cores,
 > line RFI filters (run
 > backwards) are grounded to the variac housing. Strap
 > is taken from the
 > variac housing to a well grounded water pipe. This
 > protects the coil
 > operator and the control circuits from kickback that
 > may come down the line
 > from the step up xfrmr.
 >          Two 60 cycle cables are run from the
 > variac, through reversed line
 > filters,

why the filters?

out to the step up xfrmr. No ground
 > connection is made anywhere
 > between the 60 cycle cabinet ground and the RF
 > system ground. Hot wires
 > only are given to the primary of the step up xfrmr,
 > as well as any gap
 > motors or other utility for the coil tank circuit.
 >
 > *snip*
 >
This sounds good too. Just be sure that the neutral
has a low impedance connection to ground, otherwise
everything connected to the variac case may be live.


 > Another question is where should the Line filter be
 > placed to filter RF
 > from the house wiring?  As close to the NST's as
 > possible or should it be
 > with your variac and control box.  Depending on
 > where this goes, what
 > should it be grounded to (RF or house)?

TC, strike rail, and saftey gap grounds to the RF
ground. Everything else goes to the house ground or
neutral, IMHO. The line filter belongs as close to the
line as possible, also IMO.

  And why do
 > they say you should run
 > this filter backwards?  I think I read on Gary Lau's
 > site that running it
 > backwards is wrong.

I don't think that running line filters backward will
hurt it, because they're supposed to be symmetrical.
But I wouldn't recommend it.

 >
 > Thanks in advance everyone for your help!  Hope this
 > isn't too many
 > questions in one post!

Nope. The list is here to answer such questions.

Regards,

Chris