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Re: Neon pricing


Chip,
        thanks for the advice on neon sign tranformer pricing. Today I went
over to the Neon Sign shop I've delt with before and picked up a 15KV 60ma
unit. On the way out I asked for any bad units, the owner call some of his
crew over, they grabed 2 units out of the trash pile and gave them to me.
All three were good. I now have to 15KV 60ma transformers and 1 15KV 30ma
transformer for $40. (he didn't have change and I wasn't going to argue!)


Everyone,


        I hooked up one side of the 15Kv 60ma "bad" unit in place of my Xeon
starter xformer and immediatly had 1' sparks break out from my 28" by 4"
torroid! My little starter xformer would never do that.


        Specs:

        primary:        15.5 turns inverted cone 1/4" copper tubing.
                        11.75" inside diameter
                        41"    outside diameter
                        30 degreee rise.
                        124 uH measured inductance.

        cap:            0.0137 uF measured 
                        10" by 96" rolled flashing and 0.060" polyethylene
                        in transformer oil.
                        I'm a little woried about blowing this with 15Kv.

        Fo              122KHz

        spark gap:      three 3/8" by 1 1/2" carriage bolts. I will build an
                        RQ cylinder gap today!


        Secondary:      two polyethylene trash cans glued together 7.5" to
                        8" to 7.5" 20 5/8" long.
                        wound with 22 A.W.G. magnet wire. 2 coats of water
                        based polyurethane over it. Oops!

                        33.4 mH measured inductance.
                        238Khz self resonant frequency => 13.5pF self
                        capacitance
                        133Khz resonant with 28" by 4" torroid => 30pF
                        torroid capacitance. 
                                                note: the torroid was
                               measured on the coil which was sitting
                               on the floor of the garage.


Any thoughts? comments? At this level of Power, 7.5Kv 60ma, what size sparks
are reasonable?


                                        jim

 ps.
        I mispelled tesla and this message bounced. Since then, I've built
RQ's gap and got a (measured, straight line distance) spark of 20".

                        I can't say more power anymore. I have to say MORE ROOM!

                                        jim