Again with the forms?

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

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


 Hi all,

 Does the dissapation of the secondary really matter?  I use 1/4"thickwalled
PVC 2" pipe with my small test coils, and have seen no difference between it
and thin PVC.  I really can't justify the expense of an acrylic tube for a
big coil, where the power input is magnitudes greater than a small coil
(10kva polepig vs a 15/60NST?)  Sonotube has been proven to work well, so
long as it's dry and well-prepared.
  Now true, some forms are lousy at TC freqencies, and tend to carbon track
badly.  If you're going for every mm of power output, I could see the
expense being a bit more rationalised.  But for a beginner, or even casual
coiler, PVC works grand and is a whole lot cheaper (sometimes even the big
stuff is free for the asking).  Looking at the number of coils running PVC,
even the huge systems using 1/2" thick PVC, I can't see it being all that
horrible as a form.  HDPE is wonderful for a form, but at least for me hard
to find what I *want* (different than what's available).

  Besides, odds are I'll smoke the secondary anyway trying to get that last
bit of spark out of it.  If I really expected the form to smoke, I'd have a
few smaller forms ready so I can "re-cycle" the wire onto them. Usually the
wire gets messed up at the ends, leaving a thousand foot or so of good wire
on the form.  I have wound plenty of small 2" coils off of my "bad" 8"
secondarys.  They work fine, I just have to keep a rag on the wire to knock
off the polyurethane as I re-wind the coil.

 So I'm not denouncing expensive forms.  I'm just sayin' (mostly to the
newbies) that PVC works fine, and acrylic is not a necessity for a good
performing coil.  Does it help?  sure!  Less energy dissapated= more energy
to the streamers!  But for those struggling to get the $$ for the coil, the
white (and green) 4" PVC drainpipe (mine was $12 a 10' length I believe at
Home Depot) works fine after cleaning with acetone and maybe a light
sanding.
										Just my $.02
												Shad
PS, Not tryin to open the whole can of worms again, this debate can be found
it the archives, several times, at www.pupman-dot-com