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Re: Filtering on Neon secondary

Hi all,
       Written was....

> There has been recent discussion about using ferrite toroids as a core
> for filtering chokes on the secondary of power transformers.  I have a 
> number
> of ferrite rods (approx 12mm diam, 200mm long).  Can they be pressed
> into service?  Should I bundle more than one for a core?  How many
> turns should be necessary?  (12kv 60ma neon) (ie. What is the required
> inductance?)

I have used bundles of ferrite rods for chokes in the past. Although
the incremental permeability changes with large ampere-turns flowing
through the chokes (which actually shouldn't happen) it is nearly
impossible to saturate them due to the reluctance of the HUGE airgap
from one end to the other. Actual figures? Well I make mine at least
100 times the impedance of the primary coil/capacitor at the primary
resonant frequency. Others may have different views on this. It has
worked well so far. I have checked out the PI wound chokes for radio
transmitters but the couple I got hold of were rather small. I should
say that the transformer I used my ferrite chokes with had rather 
better regulation than a neon which has a high internal inductance.
If you modelled this with the chokes in the circuit, all you would
get is a slightly higher inductance. IMO chokes aren't really needed 
with neons. I have fired one minus chokes without any problems.

    On the subject of s/n ratio, yeah, let's keep it TCs in all their
forms and high voltage in general. I'm beginning to think I made a 
mistake re-subscribing to usa-tesla. I may well end that association
if the perpetual motion gurus keep at it.

Malcolm