[TCML] Reproduction of the first "Quenched" Gap...

[Jeff Behary <electrotherapy@xxxxxxxxxxx>]

Hey All,
 
I just finished an unusual spark gap adaptation patented originally by Kinraide in 1898.  It was basically two disks, 6" in diameter, with a copper jug that would be filled with water to keep them cool.  I used aluminum, which was several hundred dollars cheaper than 1/4" thick copper plate.  
 
The gap was also patented in the UK and Germany, and was represented in a separate patent of a high frequency apparatus, later known as the "Kinraide Coil".http://www.electrotherapymuseum.com/2008/ElectricalSparkGap/index.htm
 
Here is one of the patent variations:
http://www.electrotherapymuseum.com/2005/1GBPatents/index.htm
 
It is an unusual and historic spark gap.  The plates (espescially large) had to be in perfectly parallel planes to operate correctly, because the voltage across the gap was only 900 volts, and the currents being high the sparks needed to be distributed across the whole surface of the gap in order not to arc or short...  Original spacing was around .010", but could be opened or closed for hotter or colder sparks by a lever.  People being new to spark gaps (and Tesla Coils) (and X-Ray Coils) in general at this time did not always have an easy time with it.     
 
The gap concept reappears in Germany much later as part of the Telefunken wireless apparatus, patented by Wein, Lepel, and others and becomes known universally as the "Quenched Gap" in wireless telegraphy.  (There was even a Noble Prize landed for this discovery, much to the disgust of Tesla, see below...)
 
The effect on the coil is interesting.  The sound is really strange, a movie is also in the link.  The finished outfit using this gap is almost complete.  The gaps in the photos are kept close to original for concept tests, but a third gap is being constructed with 1 1/4" diameter tungsten disks centered in each 6" disk, protruding a few thousandths of an inch from the aluminum.  This keeps the large capacity of the gap but gives it a better spark surface.  The water cooling is simple but effective.  Some tests with this little modification have been very promising.  It allows a single spark gap to handle a bunch of current - even 500mA or more from MOTs.
 
Similar concepts appear from Tesla as early as the London lecture, still years before.
 
Jeff Behary
 
Tesla on Undamped Oscillations and Tesla Coils...
 
"...I know that some have claimed that Professor Thomson also invented the so-called Tesla coil, but those feeble chirps ne'er went beyond Swampscott. Professor Thomson is an odd sort of man; very ingenious, but he never was a wireless expert; he never could be. Moreover, it is important to realize that this principle is universally employed everywhere. The greatest men of science have told me that this was my best achievement and, in connection with this apparatus [referring to schematics of Fig. 31], I may say that a lot of liberties have been taken. For instance, a man fills this space [break D] with hydrogen; he employs all my instrumentalities, everything that is necessary, but calls it a new wireless system -- the Poulsen arc. I cannot stop it. Another man puts in here [referring to space between self-inductive lines L L] a kind of gap -- he gets a Nobel prize for doing it. My name is not mentioned. Still another man inserts here [conductor B] a mercury[-arc] rectifier. That is my friend Cooper Hewitt. But, as a matter of fact, those devices have nothing to do with the performance... "
 
Nikola Tesla, Quoted from "His Work With Alternating Currents", Leland I Anderson
This book is FABULOUS!  Rare insight on Tesla's own opinion to people using his patents...taken from papers never meant to published during the famous Marconi trial disputes...
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