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Re: quiet spark gap ?



"Hello All,
 
  Has anyone designed a "quiet" spark gap; ( perhaps one utilizing
multiple
washers, a SG tube, a distributor/rotor combination from an automobile,
etc.,
etc.) ?  If so, could you please share your results and the construction
details with all of us?! 
 
  Additionally, how does one access the archives for this list?
 
 
 
  Thanx and best regards,
                                            Trent:

	Answer to your question is certainly.  So-called "quenched gaps"
consisted of a stack of electrodes, insulated from each other and sealed
to prevent air entering or leaving. Since they are completely seald the
sound is pretty well contained, and the oxygen is quickly depleted so
that electrode burning isn't a problem.  Actual electrodes were usually
circular islands on the electrodes, and so arranged as to have an air
gap of the order of 0.010".  They've been around for almost 100 years. 
I have an AMRAD "1 kilowatt" quenched gap, circa 1918.  When running it
with a 12 kV, 60 ma transformer the sound of the gap itself is almost
inaudible when the secondary of the coil is shorted so that there are no
streamers, and completely inaudible when the sparks are flying.  I have
JPEG photos of this one which I will send upon request.  Only get 16"
sparks with this gap, because the separating washers have become
compressed over the years and the gap is too small.
  
	There were many magazine articles on the construction of such gaps
during "the good old spark days".  Think Lindsay still sells reprints of
Bucher's "PRACTICAL WIRELESS TELEGRAPHY", which has a description of
one. Bucher's "THE WIRELESS EXPERIMENTER'S MANUAL" 1920 edition, has a
description of a quenched gap, between pages 119 and 121.  Lindsay's
book "The Electrical Experimenter 1916-1917" has a descriptions of both
fixed and a ROTARY quenched gaps on page 71.  These are just a few
references from my book shelves here in the study.  I'd sure like to see
someone make a quenched rotary gap, as I suspect it could be a good AND
quiet performer.

Ed