Re: LTR caps

To: tesla-at-pupman-dot-com
Subject: Re: LTR caps
From: "Reinhard Walter Buchner" <rw.buchner-at-verbund-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Mon, 14 Jun 1999 22:36:28 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Hi Gary,

> Original Poster: Gary Lau  13-Jun-1999 1557 <lau-at-hdecad.ENET.dec-dot-com>
SNIP
> I have to disagree with the suggestion that LTR caps don't work well
>with static gaps.  All long I have been using a .01 uF cap with my
>15KV/60mA NST and static gap, and this was exactly mains-resonant,
>giving very satisfactory 51" sparks.  I just tried paralleling my
>.012uF MMC cap with my .01uF Fair Radio Sales cap.  I'm now
>getting 58" sparks with the .022uF combo.  Can't complain about that!

Hey, you beat me at that power level ;o)) !! At 900VA, my maximum spark
was 51-53". However, you have encountered something very similar to what
I did: You almost doubled your input Joules (from 2.7J to 4.95J), yet
the spark length only increased by a mere 7" (of course 58" IS great, NO
question about it). This is pretty much the same thing that happend to
me. Obviously you retuned the coil. Did you try running a larger topload
on the LTR setup? I can´t try this, yet, on my coil, because I ran out
of toroid material (and $$ for this month ;o}). Did your coil give you
(aka like mine) 58" arcs plus a few "non grounded rod" interested
streamers? With my present toroid, I get 2-4 streamers of about 8-10"
length that will emit from the toroid, even though I have a 57 incher
connecting to a grounded rod (suggesting to me the toroid is way
too small). And, as you suggested, my non-cooled static gap probably
can´t handle the ~600A primary current properly any more. I always
thought the Joules (And of course the transformers capability to
recharge it "fully") were THE major factors in spark length. Yet, your
and my own experience seems to show this isn´t the full truth. Didn´t
you do some MSims a while ago, that told you 22nF would also be
about right for your RSG? I would love to see the spark length
increase you will get from static vs. rotary gap.

> One further thing of interest here.  The reason I migrated from the
>FRS cap to an MMC was that the FRS cap became warm.  With
>the two in parallel, that is no longer the case.  This isn't too
>surprising due to the no doubt lower BPS occuring with the larger
>cap, but it does show that the FRS caps can be made to work
>reliably.

Another possibility that springs to mind is the current. While you
increased the total primary current, you have now divided it up
between "2" caps (MMC and FRS). Of course, if you "exactly"
doubled the current, this theory doesn´t hold true, but if the
primary current is NOT twice the old primary current (i.e. less
than 2x), then each cap will see less current, than when they
are run alone.


Coiler greets from germany,
Reinhard