Re: Fritz vs TCBOR -- initial results in...

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

Original poster: Ed Phillips <evp-at-pacbell-dot-net> 

Tesla list wrote:
 >
 > Original poster: "Gerry Reynolds" <gerryreynolds-at-earthlink-dot-net>
 >
 > Hi Brett,
 >
 > I for one have enjoyed this tread and appreciate your experiments.  Any
 > experiments however less than ideal can be useful, even if only to improve
 > ones insight to planning the next set of experiments.
 >
 > I have a Fritz (sorta) style gap employing 12 pipes and 11 gaps and I'm
 > pretty happy with it.  I seem to get 1st notch quenching with streamer
 > loading but no power arcing.  I have no way of knowing if it is optimized
 > but between your experiments and comments on another thread about losses in
 > static gaps, I'm beginning to think that there are two factors affected by
 > the number of gaps used to build a spark gap.
 >
 > 1.  The power loss in a spark gap seems to be a function of the number of
 > gaps.  ie, the more gaps, the greater the loss (for a given current).  This
 > would be due to the voltage drop across the extra electode/air interfaces.
 > The more gaps, the more interfaces.  The voltage drop across the arc itself
 > (air only) would be a function of the length of the arc.
 >
 > 2.  The ability of the spark gap to quench seems to also be a function of
 > the number of gaps.  ie, the more gaps, the easier it is to quench.  The
 > power loss is distributed over more electodes and thus easier to cool.  Ion
 > generation is distributed and maybe easier to evacuate.
 >
 > If the above is correct, then #1 jwould say to reduce the number of gaps
 > while #2 would say to increase the number of gaps.  Maybe the optimum design
 > is to increase the number of gaps only until desired quenching is obtained.
 >
 > Comments welcomed.
 >
 > Gerry R

	I have an old (ca 1918) AMRAD quenched gap which has about 20 separate
gaps, each totally enclosed and with circular plane electrodes about 1"
in diameter.  Individual plates are separated with a fiber insulating
washer and the whole stack is kept under compression with a jack screw.
Originally used in spark transmitters of course.  Works just fine on a
small TC running off a 9 kV, 60 ma transformer.  Almost no sound from
the gap itself, and a nice "hissing" sound from the streamers because of
a rather high spark rate, not measured.  In the last 85 years the fiber
insulators have been compressed enough that the breakdown voltage for
the assembly is only about 7 kV, resulting in the high spark rate with
the 0.009 ufd primary capacitor I'm using.

	The design and function of such gaps is well known and discussed in the
literature of the times, so I won't go into it here.  Note that the
spark is NOT in air.  After the assembly has run for a while all of the
oxygen in each of the little sealed cavities is exhaused and further
running causes the sparking faces to be a nice clean pink color.  The
objective of the quenching is, of course, to cause the spark to
extinguish when BOTH current through it and voltage across it go to zero
simultaneously, as at a "notch".  As a matter of interest one of the
features of the quenched gaps which was often mentioned is that they
could be operated at lower voltages than the open-air gaps such as
SRG's.

Ed