Re: In need of a vacuum tube

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Shad <shenderson@xxxxxxxxxxxxxxxx>

Matt, All,

For grid leak resistors, use wire-wound ceramic power resistors.  Do
*NOT* use the aluminum heatsinked power resistors! I've had them explode
like little cannons and blow out a chunk of porcelain like a
projectile.

For grid leak, I generally use a 3-5kv cap in the 2-5 nF range.  Grid
leak is usually in the 8-20kohm range for me.  The bigger the value of
the grid leak resistor, the slower the charge on the cap bleeds off, and
the less power the coil will pull.  Lower values make the coil run
smoother, but increase the power drawn.  Lower values also must
dissipate more heat because of the higher current they see.  My grid
leak coils are generally 12-15 turns of 26ga wire, placed physically
below the primary coil. Less voltage stress on it, and less chance of a
flashover arc hitting it and imparting some nastiness to the tube.  I
like to wind a piece of cardstock on the primary form, then wind the
grid coil on that.  That way I can slide the grid coil up or down to
increase or decrease the amount of drive the tube sees.

Hope it helps!

Shad H.

On Mon, 2006-03-20 at 18:35 -0700, Tesla list wrote:
> Original poster: Fucian@xxxxxxx
>
> In a message dated 3/20/2006 4:59:44 P.M. Pacific Standard Time,
> tesla@xxxxxxxxxx writes:
> Original poster: "Hooper, Christopher AZ" <christopher.az.hooper@xxxxxxxxx>
>
> Good day great coilers,
>
> I agree that tube coils are cool indeed. Here is a little link, as
> dipped the chokes in epoxy and rotated them till the epoxy cured (5
> mins). Here is the link @
> http://users.cableaz.com/~chooper/images/tubeiew.jpg. Running two 1kwatt
> Mots I was able to get 30 inch sparks, a cool little animated gif @
> http://users.cableaz.com/~chooper/images/sparks_1.gif.
>
> Happy tube coiling to you.
>
> Rgs,
> Christopher Robin
>
> Neat!Time to audio mod that thing now!
> Whats a good way to calculate the grid leak resistor/capacitor?I have
> 10 7kohm25watt resistors(abit large for 25watts). I was thinking
> around 35kohms/.001uF 10kv ceramic?
>
> This resistor/capacitor dictates how much current the coil will draw no?
>
> Matt
>
>