Terry filter + isolation transformer

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Qndre Qndre" <qndre_encrypt@xxxxxxxxxxx>

Hello coilers, espacially Terry!

Terry's filter is designed to operate with the center winding of an 
NST tied to RF-ground which is where the center tap should be tied to 
when using a transformer designed for midpoint-grounded use anyway. 
But what if the transformer is not an NST but a true isolation 
transformer? In this case the whole tank circuit can be operated in 
floating-ground condition which is good for several reasons: You can 
do measurements of the voltage across any part of the circuit by 
grounding any point you want and measure the voltage which appears on 
another point of the circuit. Strikes will not hit the tank circuit 
since it will not pass current to the ground. The experimenter has a 
better chance of not being electrocuted by accidently touching a part 
of the circuit while having low resistance to ground. Possibly there 
are many other advantages. But how to use Terry's protection circuit 
in such a floating-ground circuit?

Possible configurations I see:

1. Just connect the two connections from the transformer's secondary 
to the "Hot1" and "Hot2" wires on the schematic while leaving the 
"NST ground" and "RF ground" connection unconnected? That way the RF 
will still flow through the MOVs/Caps and "cancel itself out" which 
is what we want. However, "symmetric" interference occuring at both 
wires will be ignored but it seems like this shouldn't do any harm 
anyway since it will not cause current to flow through the 
transformer's secondary. Also the floating-ground condition is preserved.

2. Connect "Hot1" and "Hot2" to the transformer's secondary and "RF 
Ground" to RF ground but leave "NST Ground" unconnected? Doesn't seem 
to make any sense to me since the "Hot" wires aren't in any way 
related to RF ground during normal operation. Looks like it will just 
make the isolation transformer effectless since the voltage gets some 
reference to ground.

3. Connect one end of the transformer's secondary to RF ground, 
double the number of MOVs/Caps/Resistors in series in the filter and 
connect the other end of the transformer's secondary to the 
connection "Hot1" of the filter while dropping all the parts below 
the ground wire on the schematic. Sounds very implementable. It's 
just that grounding the secondary of the isolation transformer kills 
all of the advantages mentioned above. ;)

So the most logical configuration seems to be the first one. Anyone 
seeing problems with that configuration or wanting to suggest another 
one? This question is especially for Terry since I'm sure he will 
know best how his own filter design works, what it's intended for and 
what it's not intended for.

Regards, Q.