Battle of the Capacitors

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Original poster: "sundog by way of Terry Fritz <twftesla-at-uswest-dot-net>" <sundog-at-timeship-dot-net>


 Hi all,

 Did an impromptu test over the holidays.  I have my polepig up and running
on 120v (the 240v drop is coming along slowly), running ~2.5kva.  I'm using
a 240bps sync gap, and an 8" coil.  Comparison was by the gap sound and
streamer quality (length, power, etc)

 On the testbed was a 35kv30nf Maxwell, a 16.7kv35nf MMC (panasonic caps),
and a 30kv34nf cap (3 10kv .1uf caps in series).  The gap was left at the
same position for each cap, as the capacitancies were pretty much the same.
Yep, I know I'm seriously overvolting the MMC with a 14.4kv polepig, but
what the hey, it's all in fun!

 The MMC gave a nice rich sound.  There was no heating of the cap bank, and
performance was good.
 The 3 10kv caps gave the gap a bit sharper sound, and also did not heat.
The streamers were maybe 1-2" longer (measured byfrequency of hits to a
grounded target just inside of strike range).
 The Maxwell gave the gap a very sharp, harsh sound.  Again, no heating of
the cap. The streamers grew ~1" longer with the Maxwell.

  The MMC is the biggest of the caps as far as actual bulk goes, followed by
the 3 10kv jobbers, then the maxwell (roughly the size of a brick).

  So there isn't much difference between the performance of the caps.
Cost-wise, I spent $1.40 on each Panasonic cap(7 strings of 11), and about
$10 to mount them. Right around $120 for a 16kv35nf cap.  I spent $40 each
on the 10kv .1uf caps.  Flattened 1/4" tubing for interconnections, so I'm
figuring ~$125 for a 30kv34nf cap.  The 35kv30nf maxwell was about $130 when
all was said and done.  Pricewise, they are about the same (a new maxwell
will almost certainly cost more).
  Repair wise...I have 4 of the 10kv caps.  That means I have 1 spare.  If
the Maxwell blows..well..I'll probably cry a bit and start hunting for
another.  The MMC...I have some spare panasonics hangin' out on my workbench
for the "oopsies" when (and if!) they occur.


 My conclusion now that i've run the caps at low power level,
   The MMC is probably the cheapest for most people, as I lucked up on the
other caps.
   The professional-cap MMC (big caps in series/parallel) will probably
handle current better.
   The professional single cap holds the size advantage, but you're stuck
with the values you get.  And you can always use more capacitance ;)

    So unless you luck up on a pro cap(s), go MMC!  The actual performance
difference is nothing to write home about, and you end up with a cap that's
easily stackable to whatever voltage/capacitance you need.  And once the
240v drop is in, we'll see how MMC's run at the multi KVA levels. (like
5-15+kva!)  I've got a polepig and a 60A breaker, and I'm not afraid to
chunk 'er wide open!  =^))
															Shad