Indulge me...

Back in the early 1980s I taught apprentice electricians...an older
colleague, who had been 'discharged' as a Major in the German Wehrmacht
Engineers -and made no secret of it, was the HV Instructor, he and I found a
common interest in the works of Tessla.

We contrived to use the resources of @#$% make one 'mother' of a Tessla
Coil.

Suffice to say the primary transformer was a kVA or so of a large
fluorescent sign transformer (20A 240V supply), 3/4" diameter, carbon rod
arc-gap (shielded), 1/2" plate glass plate capacitors and a fine wire
secondary coil wound (in the machine shop)on a 10/12 foot(?) 12 inch
diameter cardboard  former carpet roll former.

It was unofficially assembled in the high voltage lab...much more
unofficially 1st year apprentices were routinely and ritually assembled into
a the darkened room...then the light display began!

After a suitable period we would then emerge from the darkness with
fluorescent tubes and the arcs would descend...while our hair was on end and
arm/body muscles cramped...the apprentices were generally cowed.
(Explains far too much of my present demise!)

Another era...the ritual was too soon uncovered, properly @#$%
Administration and Workers' Compensation got involved, certain persons
chastised and the devilish Coil demolished.

The point of this saga...

Latterly we discovered that Industry Canada (DOC) had too become involved on
an investigative basis; we learned that during our exhibitions, local
broadcasting and even low band TV in the immediate locale was reportedly
obliterated but certainly interfered with.

So...perhaps the harmonics of a spark gap are indeed legion?
Mmmm
73
Martin
VE7MM/VE0BC/G4EZG

PS SOooo... Steve/Scott...ZLland on a spark gap next time???