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What gets connected to RF ground?
Original poster: "Jeremy D. Gassmann by way of Terry Fritz <teslalist-at-qwest-dot-net>" <gassmajd-at-email.uc.edu>
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. Another site says
that only the secondary gets the ground and the NST and safety gap and
filter get house ground. Another variation of the latter is the you leave
the NST center tap ungrounded. Still another different variation that goes
along with the former is as follows:
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, 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.
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)? 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.
Thanks in advance everyone for your help! Hope this isn't too many
questions in one post!