These are some shots of my new 2.5" coil during initial testing.
one 7.5/20 NST, 10nf MMC and 4 segment RQ/TCBOR spark gap.
~11.7 turns of bare 4AWG solid wire.
These are a few shots to a grounded target. These were taken while running a 7.5/20 NST. Maximum spark length is about 12". Shown running with it's new primary.
And here is a short video clip. (626kB)