#34 SSE bipolar Coil

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

Original poster: Parpp807-at-aol-dot-com 

Hi all,
I finally lit up my small bipolar wound with 14.5 inches, around 1450 turns 
of very old #34
single-silk-enameled wire. It is wound on a piece of 2.25 inch OD PVC. The 
primary is
four turns of 3/ 16 copper tubing. The green silk produced a fine looking coil
that looked like a piece of fine green cloth. That was before I moped on the 
polyU. The varnish turned the beautiful green silk into a yuch black. My 
guess is the polyU destroyed
the silk. I found it impossible to keep any sort of tension on the thin wire; 
something is needed to keep the coil from unraveling.  I think I should have 
wrapped the coil in transparent scotch tape or vinyl tape instead of using 
the polyU. The coil inductance is around 30 mH and with the 0.22 MMC tuned in 
at around 3.25 turns on the primary. I get a 14 inch
spark between two pieces of #6 wire for the antenna. The spark is thin and 
feathery and
closer to the blue than it is to white. I tried a primary coil with a 4 inch 
diameter but this  
close spacing is too tight a coupling and there was much primary / secondary 
arcing. A
change to a spacing of nearly 2 inches, slightly less than a six-inch 
diameter, tamed things down. I have some silicon rubber sheeting that's 1/32 
inch thick. Wrapping that around the secondary almost eliminated the arcovers 
with the 4 inch diam primary and 
also hid the black coil. :-)) Increasing the spacing between coils also 
eliminated the need for the silicon sheeting.

There may be a little learning taking place. I have a question to ask of the 
list:
The desirable D : L ratios are usually given as something between
3 - 6 to one. For the 1/2 wave bipolar, does this apply to just 1/2 the 
length of the coil,
or to the entire length? Does this little coil with a diameter of 2.5 inches 
and a length of
14.5 inches have a ratio of 6.4 or 3.2? I suspect it is the latter and the 
ratio applies to
each side of the dipole.

Happy day,
Ralph Zekelman