Re: Resonant Frequency

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi all,
        In connection with this thread:

On 23 Feb 2002, at 18:25, Tesla list wrote:

> Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<evp-at-pacbell-dot-net>
> 
> Tesla list wrote:
> > 
> > Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <Goinbonkers-at-aol-dot-com>
> > 
> > Quite possibly.  Tesla did experiment with them.
> > Mike
> > 
> > >
> > > Does this suggest a cone might resonate exactly at quarter wave?
> > >
> > > Dave
> > >
> > >
> 
> 	Without running the experiment it would be difficult to prove, but I
> suspect that at some ratio of height to diameter the condition would be
> met.  It surely is for a solenoid.  However, NOTHING magic happens!!!
> 
> Ed

Someone mentioned 0.3 for a solenoid which sounds reasonable. 
Wouldn't be a terribly useful spark producer though. But further to 
this, aspect ratios dropping to those for flat spirals are going to 
do two things: the increase in mutual L outstrips the drop in 
capacitance which starts to rise again, and the Q is probably going 
to be quite poor. That probably sounds absurd at first glance but 
there is evidence of Q degradation in conical resonators and it is 
well known that Q peaks in a h/d=1 spacewound solenoid with no 
topload. Dave Thompson's measurements suggest that the Q of his 
spiral resonator is poor and the performance appears to reflect this. 
Against that, one has to consider the performance of spiderweb aerial 
coils as used in radio receivers. A few thoughts to drop into the mix.

Regards,
Malcolm