Hi Paul, Here is a bunch of data on my big secondary coil. Bare and with a toroid at two different heights. Pictures of the setup are at: http://63.225.104.218/test/TeslaCoils/Misc/PaulNich/ I am still working on the postscript thing. I am sure I can get it going when I have a bit more time. With the secondary on this ground plan. It's inductance measures 74.1mH (normally 75.4). The terminal is high enough that it does not effect the inductance. The voltage drop at the higher order harmonics was too small for the measurements of impedance to be trusted. The fundamentals should be very close. I used a high frequency variable resistor to find a similar drop at the given frequencies and then measured it. The fundamentals are much more pronounced (especially with a terminal) than the f3 and f5s. Let me know if this is ok or if you have questions. Cheers, Terry ======================================= System name: BIG LTR Coil Bare Coil Website: http://63.225.104.218/test/TeslaCoils/MyCoils/BigCoil/BigCoil.htm Owner email: terrellf@uswest.net Distance of nearest wall (if any): 5feet 4 1/2 inches to three wood walls. Height of ceiling (if any): 6feet 11 1/2 inches Radius of effective ground plane (if limited): 5feet Secondary... winding radius: 10.26 diameter 5.13 radius winding length: 30.0 inches DC winding resistance: 69.87 ohms number of turns: 1000.5 wire diameter or gauge: 0.0201 inches #24 height of base of winding above the ground plane: 1.0 inches Disc Primary (if present)... Not used inner turn radius: outer turn radius: height of primary plane above the ground plane: Cylinder Primary (if present)... Not used winding radius: winding length: height of base of winding above the ground plane: Strike ring (if present)... Not used radius: height above ground plane: Toroid (if present)... inner radius: outer radius: height of toroid plane above the ground plane: Frequencies... 1/4 wave (f1): 148.37 kHz 3/4 wave (f3): 353.40 kHz 5/4 wave (f5): 513.84 kHz Impedances (if available) ... 1/4 wave (z1): 784.17 ohms 3/4 wave (z3): Not accurate 5/4 wave (z5): Not accurate Please send your results to paul@abelian.demon.co.uk ================================================== System name: BIG LTR Coil 43 Inch High Toroid Website: http://63.225.104.218/test/TeslaCoils/MyCoils/BigCoil/BigCoil.htm Owner email: terrellf@uswest.net Distance of nearest wall (if any): 5feet 4 1/2 inches to three wood walls. Height of ceiling (if any): 6feet 11 1/2 inches Radius of effective ground plane (if limited): 5feet Secondary... winding radius: 10.26 diameter 5.13 radius winding length: 30.0 inches DC winding resistance: 69.87 ohms number of turns: 1000.5 wire diameter or gauge: 0.0201 inches #24 height of base of winding above the ground plane: 1.0 inches Disc Primary (if present)... Not used inner turn radius: outer turn radius: height of primary plane above the ground plane: Cylinder Primary (if present)... Not used winding radius: winding length: height of base of winding above the ground plane: Strike ring (if present)... Not used radius: height above ground plane: Toroid (if present)... inner radius: 5.25 inches outer radius: 11.75 inches height of toroid plane above the ground plane: 43.0 inches Frequencies... 1/4 wave (f1): 99.17 kHz 3/4 wave (f3): 320.56 kHz 5/4 wave (f5): 490.28 kHz Impedances (if available) ... 1/4 wave (z1): 408.1 ohms 3/4 wave (z3): not accurate 5/4 wave (z5): not accurate Please send your results to paul@abelian.demon.co.uk ================================================ System name: BIG LTR Coil 45 Inch High Toroid Website: http://63.225.104.218/test/TeslaCoils/MyCoils/BigCoil/BigCoil.htm Owner email: terrellf@uswest.net Distance of nearest wall (if any): 5feet 4 1/2 inches to three wood walls. Height of ceiling (if any): 6feet 11 1/2 inches Radius of effective ground plane (if limited): 5feet Secondary... winding radius: 10.26 diameter 5.13 radius winding length: 30.0 inches DC winding resistance: 69.87 ohms number of turns: 1000.5 wire diameter or gauge: 0.0201 inches #24 height of base of winding above the ground plane: 1.0 inches Disc Primary (if present)... Not used inner turn radius: outer turn radius: height of primary plane above the ground plane: Cylinder Primary (if present)... Not used winding radius: winding length: height of base of winding above the ground plane: Strike ring (if present)... Not used radius: height above ground plane: Toroid (if present)... inner radius: 5.25 inches outer radius: 11.75 inches height of toroid plane above the ground plane: 45.0 inches Frequencies... 1/4 wave (f1): 97.87 kHz 3/4 wave (f3): 321.4 kHz 5/4 wave (f5): 490.16 kHz Impedances (if available) ... 1/4 wave (z1): 407.72 ohms 3/4 wave (z3): not accurate 5/4 wave (z5): not accurate Please send your results to paul@abelian.demon.co.uk