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Re: free standing coil

Ed, thanks for the comments.
> 
>     On the practical side of the Q issue, I asked Richard Hull about
> the Q's they get for their Magnifiers. He estimated that the loaded (
> meaning with terminal connected ) coil Q was about 80. This is probably

I define loaded Q in the classic sense of having the coil loaded
(in this case by spark resistance). In a normal use of a transmission
line it is normally by its characteristic impedance. Spark loading
is rather less well defined than this (depends on spark current and
degree of spark channel ionization).
L/C ratio is the definitive factor in his Q measurement. The coil 
former will add to R in the equation below as will spark when run-
ning.
(Q=1/R x SQRT(L/C)
Characteristic impedance approx SQRT(L/C) for high Q coil

> since they used a fairly thick (1/4"?)1ft diameter PVC form, but they still 
> get 100+ inch arcs at 7kW of input power. So, perhaps it is not worth
> the investment to obtain the highest Q's?!? 

It would be an interesting exercise, but since the primary will be
the determining factor when powered, you're probably right. System
(coupled) Q is an aggregate :   Qsys = SQRT(Qp x Qs)

>     A related request for the group:

No problem. I'll post some data directly to avoid clogging the list.
I'll try and get it together this weekend.
I once tried the same trick on usa-tesla and got no help at all :-(

> The method I use to determine Q is the 1/2 power bandwith method: 

Ditto

> 1) find the resonant frequency f0 of your coil with/without terminal
> using a sine wave signal generator

Signal lead connected directly to bottom of the coil ?  Do you want
to take sig. gen. impedance into account ?

Malcolm