Tuning Question

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Original poster: otmaskin5@xxxxxxx 

I've read plenty about the importance of tuning coils at low power 
(variac & gap width) to avoid damaging components until resonance is 
achieved.  I also recall a post discussing, once a coil is tuned at 
low power, you need to further tune the coil at full power due to 
additional secondary capacitance created by the streamer itself.  I 
have some questions about this.
   * Is additional capacitance of a full power streamer significant 
enough to warrant the additional tuning excersize?
   * If so, I would assume you are looking to increase primary 
inductance to compensate for increased secondary capacitance - so 
you'd be tuning outward (increasing primary turns) - correct?
   * I tried this & seemed to find increased performance tapping the 
primary at an additional 3/4 turn - i.e., from 13 7/8 turns to 14 5/8 
turns on my 15/60-0.015uF system.  Seems like a lot of additional 
primary for the small increase in secondary capacitance.  Does this 
seem to be in the ballpark for full power tuning point?
My NST died a few days after reaching this higher performance 
level.  I'm wondering if I killed it with improper tuning.

I want to optimize performance, but would also like to avoid killing 
another transformer.
   * Any tips or suggestions on doing this additional full power 
tuning excersize.  I'm concerned I'm missing something here.
Thank you - Dennis Hopkinton MA