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Re: Primary construction



Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com> 


This points out one of the great dangers of beginners in fabricating a
"fixed" primary and not using some "scrap wire" to explore the full possible
tuning range with their caps.

My advise is to remove your present primary and wind up a quick primary of
perhaps 30 turns of scrap wire (ga. not important for quick tuning test) and
sand off a bare spot at each turn (stagger a big to prevent flashovers from
pri turn to turn).  Your can even use some scrap cardboard with slots cut in
it as a quickie primary support.

With a full 30 turns you can explore the output at 30% variac setting at
each tap until you find the proper resonance point.  Then you will know what
type of primary to wind as a final "finished product" of copper tubing ---
add 2 additional turns in case changes are necessary.  This also allows you
to quickly calculate the max. dia size of your sub-base assembly before
building one too large or with too many primary turns that act as an
auto-transformer and sometimes try to flash over in the outer windings.

Terry's advise might work, but if not, then go back and do the complete test
before you lose all your patience.

Don't feel bad --- I've been tripped up with too few turns available also
back in the 60's on some earlier coils.

Dr. Resonance


 > In general, you should tap you primary at about 58% of what it was at
 > 2nF.  Search around that area for the new tune point.
 >
 > Cheers,
 >
 >          Terry