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PRIMARY STRIKES


Quoting Ed Sonderman:

 ES> I watched the coil running last night for quite awhile.      
 ES> When I get the loud discharges in the primary (pop like a    
 ES> firecraker and bright flash) I don't actually see a strike   
 ES> from the discharger hit there. Is it possible this is being  
 ES> caused by something other than a strike from the secondary?  
 ES> Like a breakdown of the primary itself?  I am using 3/8      
 ES> copper tubing on 3/4" centers i.e. 3/8 spacing.

Yes, getting all of the little electrical breakdowns sorted out 
of a new system can be a challenge. There are numerious
possiblities, all minor, that cause this type problem.

Ask yourself some questions: 

Is the breakdown occuring right before, during, or after a 
strike to the primary? All primary/tank circuit striking 
must be eliminated.

Is the flash occuring in the same spot, or area, repeatedly?
Look for minor defects in the primary winding: kinks, turns too
close together, pinching, ripples, etc. that would facilitate 
a breakdown between turns. If areas such as this are located,
then work them out as best as possible, and/or then place 60 mil
poly between turns for extra high-voltage hard insulation.
Sometimes a primary may require several strips of plastic between
troublesome turns.

Is the secondary coil coupled too closely to the primary? This
coil design offers exceptional efficiency, and it is easy to
overdrive to secondary coil with too much energy. This is 
especially true if the toriod is too small. The resultant over-
load can "kick back" to the primary coil and cause a breakdown
between turns and/or the safety gap to fire. The solution here 
is to raise the secondary coil up in relation to the primary to
loosen the coupling slightly. This will actually increase the
performance if the system was overcoupled to begin with.

Follow up on these, most likely one or more of these adjustments 
will result in diminishing breakdowns. 

 ES> The other day you asked if the RF chokes are far enough      
 ES> back. I don't know, I think so.  

Four or five feet minimum.

 ES> You said they should be mounted off axis.  Can you elaborate 
 ES> on this?  

Yes, the cores should not be on the same plain as the primary.
The relationship of the ferrite core needs to be 90 degrees off
axis with the alignment of the primary. In other words, if the
primary is a pancake or saucer on a table, the ferrite core needs
to be a hoop a dog could jump through. The pancake and the dog
hoop are 90 degress off axis from one another

 ES> You said they may be too large or too small.  I used 1.5" OD 
 ES> ferrites from Marlin Jones P/N 5065-CH.  I understand how    
 ES> they could be too small. I don't understand how they could   
 ES> be too large.  

You are right I am sure. The mushy tune problem is most likely
your ground and ground path. Loosening up the coupling too may
also help if you are running a little tight.

 ES> I have a question about tuning.  Here's how I do it.         
 ES> Running about 1/4 power with only a couple of the spark gaps 
 ES> hooked up,  I adjust a ground wire above the discharger      
 ES> about 7 or 8 inches away - to draw a constant series of      
 ES> sparks.  Then I adjust the primary tap until the white hot 
 ES> center section of the sparks is the longest.  Does this      
 ES> sound ok?

Well Harry Goldman used to say " Tune for Maxium Smoke! ",
which is what coiling is all about. I always use the longest
possible spark as a tune guide. Someday, when I get more time,
I will tell about building a "Tune Indicator" that I saw
demonstrated using a series spark gap coming off the secondary.

Richard Quick

... If all else fails... Throw another megavolt across it!



... If all else fails... Throw another megavolt across it!
___ Blue Wave/QWK v2.12