Subject: WIRE CHART
Date: Fri, 29 Mar 96 22:55:22
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Te> Robert, Brad and any concerned parties,
Te> This form of "basket weave" winding is ancient and works great in
Te> radios where microhenries are needed, but the inductance per unit turn
Te> drops way down, too. In the common class of amateur coils, 20"
Te> diameter and smaller, the interturn capacitance is a virtual
Te> non-issue. High inductance is of prime importance as the output is a
Te> function of current delivery rate and coil inductance. Tesla only
Te> fiddled with the problem of internal capacitance in Colorado due to
Te> the tremendous diameter of his coils where just one turn added a
Te> significant capacitance to the coil.
Te> Richard Hull, TCBOR
Te> From: "Robert W. Stephens" <rwstephens-at-ptbo.igs-dot-net>
Te> Hello Group,
Te> I'd like to jump in here and put in my 2 cents worth. This actually
Te> costs me about 2.8 cents in my quaint Canadian money. I think I
Te> understand the
Te> physical geometry of the coil winding technique
Te> which Brad Alheim is attempting to describe, and I'd like to suggest
Te> that where it's merit might best be used to advantage, that is to say
Te> as Brad points out,
Te> it has reduced interturn capacitance, might be a good way to wind a
Te> high performance SECONDARY coil! This is where interturn capacitance
Te> is really a problem to performance. You have to charge this built-
Te> in distributed capacitance every time you send a power pulse up your
Te> 1/4 wave helical resonator. Less capacitance here from a different
Te> winding technique
Te> and subsequent reductions in the interturn capacitance from
Te> dielectric protective coatings, the coil form, etc., would let more
Te> energy arrive at the top where we want it! This is one way (I
Te> suspect) where coil length to diameter aspect ratio can contribute a
Te> very real yet not commonly understood influence to coil performance.
Te> Congratulations Brad for inspiring thought in this direction!
Te> The down side to this idea however (if I've got Brad's concept
Te> visualized correctly), is the mechanical reality of
Te> winding thousands of feet of wire onto such a specifically convoluted
Te> form with a continuous and repetitious hassle of every second post
Te> being in the way
Te> that you need to get your supply reel of wire around. In a factory
Te> a machine could be made to do this through the economy of mass
Te> production. In the home workshop this might be a good example of
Te> 'diminishing returns'. A thousand times the effort for a 5%(?) gain?
Te> Comments anyone?
Te> Happy coiling, R.W.S.
Sounds like a great idea, I never thought of using a honeycomb winding for
the SECONDARY! The winding could be facilitated by using an external
split "ring" with removable pins for the winding arbor, and after winding
a few inches, the winding would be "varnished", the arbor removed, pins
inserted in last couple of windings. split "rings" put in place to hold
pins, and wind again. This would be tedious, but would be challenging,
fun, and it MIGHT EVEN WORK! The wire is wound from the "end" and it is
wound with "wire in hand", weaving it in and out between the pins. I've
wound many coils this way (largest about 8" diameter and 12" long for a
longwave 160-190kHz. transmitter antenna coupler. Used very heavy litz,
and it worked well, pretty coil, too!)
I've yet to make a REAL coil, (largest was a 24" high x 3" dia. fired
with an ignition transformer and a stationary gap, not impressive at all,
but fun to fiddle with. generated LOTS of RFI, though! Know better now.)
going to start soon. I'll make 2 seperate secondaries, one solenoid wound,
and one with the honeycomb winding. I'll see which throws best spark!
Don't have a pig yet, (I've got my scrounging source working overtime at
the electric company) but will probably use a large ignition transformer
or neon for starters if I don't get a pig by the time the coils and gap
are made. Will use a homemade cap for starters, until I can afford one of
those nice caps you guys are talking about! (working on a real LOW hobby
budget right now, $0.00!)
I have a couple of plastic pulse caps I was thinking about using, but after
reading the posts on the pulse cap subject, I decided to save them for
their intended use and roll my own.
Let the sparks fly!
Brad Alheim brad.alheim-at-the-spa-dot-com
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