[TCML] Subject: Overheated Secondary

[bartb]

Hi Wyatt,

I've never done it myself. Since Aron has, I guess it is possible. Under 
oil is a good idea, but remember regardless of shunts or not, those 
secondary windings are voltage fragile. When removing the shunts, the 
current is going to climb and the tranny impedance lowers. With my 12/60 
with 1/2 the shunts, I measured about 200mA. So the impedance dropped 
from 200k down to 53k (10.6kV at 200mA when tranny was last measured). The 
reason I mention this is that to keep a tranny in long life, LTR is a 
great help. Problem is, LTR value jumped from .02uF to .075uF and even 
the resonant value is now up at  .05uF.

If you don't make some system changes, you can inadvertently hit 
resonance depending on the cap value. If you know the change made, then 
you can design around it. I'm running my NST coil about 2.7 times lower 
than Cres with no problems (safety gaps, gap widths, etc. are of course 
important).

Take care,
Bart



nancylavoie at comcast.net wrote:
> Bart, I was wondering if you would know off hand if it is feasible to completely remove the shunts of  a 15/60 NST  without burning up the secondary winding? Any estimate as to what the current output might equal when used in a TC? Any comparison to the durability of  MOT's? Looking for a winter project. Wyatt
>