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Q, Gaps, Etc

>Gap adventures:

>I just bought a squirrel cage fan this past weekend to use with my 
>multi-tube gap
	Wotsa multitube gap?

>I then tried the  blower using an old single gap that I had made from two
>bolts. The  secondary discharge with the blower on was about twice what I was 
>getting with the blower off!
	I bet it was.

	Gaps are kind of an obscure art/technology.  The old time wireless folk
	put a lot of development into them.  I have mucho old tyme wireless
	books.  I suspect that some of the Lindsay Pubs books on olde tyme
	wirelss would be useful.  The theory (for RF work) is that one wants
	a _spark_ not an _arc_.  They are different things.  (There was an
	_arc_ transmitter.  Whole different thing from a spark gap transmitter.)

	In general, a long gap is good.  A cooled gap, or one which is "blown"
	(as above) is better yet.  A "quenched gap" consisting of smaller gaps
	in series is as good, maybe better, depending on implementation.
	best-best is the rotary gap.  For small powers, it proably does not
	justify the complexity, but for high powers, it is a win.  Another
	technique was to run the gap in something other than air, tho gains
	here, versus a good quenched gap are minimal.

>And finally some questions:  Does anybody know how to measure the 'Q' of a
>coil?
	Q == Inductance over reistance, as i recall.
	But.  Q of the coil is of less interest than Q of the _system_.  Which
	includes the resistance and losses in the capacitors, etc, etc.  And if
	the coil is running as a helical resonator (cf Corum & Corum) the Q gets
	a bit more complex yet.

	WITH THE MAIN POWER OFF....

	Experimentally, one can excite the coil (or system) with a low power
	signal, and measure the voltage.  Excitation can be by direct
	connection, coupling by a link turn or what haveyou.

	Measure the voltage devoped across the whole coil.

	Do this for a range of frequencies, from well below resonace to well
	above.

	The peak is the resonant frequency.  The "slope" indicates the "Q".
	A high Q coil/system  will have very little voltage when "off
	resonance" even a little and a higher "magnification" on resonance.
	Plot the voltage values against frequency.

	To get high Q, use "Fat" wire. or flat strap.  (tho strap is not
	usually practical...)

	The voltage measurement will require a voltmeter that is OK In the
	frequency of interest OR a 'scope or...  (It has been argues that
	most of what Tesla was doing in Colorado Springs was measuring the Q of
	the system, and pushing it as high as possible.).

	The low power excitation is typically a signal generator, one with
	digital control makes getting the frequencies accurate easy, but is
	expensive...

===============================
A note of introudction:
	I work with RF problems, and high voltages, some.
	I am one who approaches Tesla and "his technology" as straight
	electrical/RF engineering.

	regards
	dwp