[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [TCML] air core

    With care you can create a coil with no former at all..

If you make a thick paper former and coat the out side with wax paper. Wind the coil onto the wax paper and coat with multiple layers of varnish until you have a really thick coating. Carefully fold the inner paper tube in on its self and remove from the coil. You now have a coil held together with only varnish.

I have made a couple of these, and I have seen no changes in properties from a coil wound in a more conventional way. The coils do look good on their own, but when you have added a top load and a primary, they look almost exactly the same as a regular coil.

I'm my opinion, not worth the extra hassle for a flimsy coil compared to using a more solid former.


On 11/11/2012 18:42, Ed Phillips wrote:
As long as the form is clean and dry enough that there isn't any discharge along the surface the performance will be pretty much independent of the material. I've experimented quite a bit with making coils for receivers using various forms of PVC tubing, ordinary mailing tubes with or without drying and sealing, and even a piece of wood and couldn't tell any difference in the Q at 4 MHz, well above the frequency of most TC's. The purpose of these particular tests was a report that some forms of black and grey PVC pipe were quite lossy when used for coil forms and that sure wasn't true for my cases. I certainly agree about the 'art and appearance' business. A neatly wound coil on a 'good looking' form can be a real thing of beauty!


Jim Lux wrote:

On 11/10/12 3:32 PM, JJR+weluvlucy.com wrote:

Hello to the list,
Has anyone ever built a secondary coil without a coil-form. Wouldn't air
be the ideal coil-form because it has a dielectric constant of 1?

Tesla mailing list