Re. need some input

To: tesla-at-pupman-dot-com
Subject: Re. need some input
From: Gary Lau 19-Mar-1999 1601 <lau-at-hdecad.ENET.dec-dot-com> (by way of Terry Fritz <twf-at-verinet-dot-com>)
Date: Fri, 19 Mar 1999 19:48:34 -0700
Approved: twf-at-verinet-dot-com

>Original Poster: "art" <ignatz-at-datasync-dot-com> 
>
>my first tc was a bugzapper getting 2 1/2 inch sparks i was amazed at the
>results i got with no planning! the next one will have some design
>configuration to it. i just wanted it to work good the first time with my nst.
>and not fry anything up :-)
>well i have a nst on hand 12k/30ma. i wanted to see if a few things mattered
or
>not?
>1, safty gap setting should be gaped just far enough that there is no spark,
>and between the terminals should be a good rf ground. 

Correct.  Make sure the gap is set with the tank circuit disconnected.

>2,do i need more than one set of gaps? 

For the safety gap, no.  Just a single one as you described above.

>3,should the safty gap be as close as possable to the xformer?

Yes, reasonably so, though I doubt several inches makes any difference.

>4, is it a good idea to shield the xformer?

You mean magnetic shielding?  No need for that.  It should be shielded
against strikes from the secondary though.

>5, can i put the xformer to close to the coil?

I have mine about 15" below the primary.  Theoretically there will be
some eddy current losses, but I doubt it will make an observable
difference in performance.

>SPARK GAP
>is there a good configuration to start with. 
>more than one gap?

I've had good results with both single and multiple gaps.  But in both
cases, it's VITAL to observe that the electrodes be rounded and smooth on
all arcing surfaces, and that the arc channel have forced airflow through
it.  Don't even bother if there's no airflow, performance will be
terrible.  A good starting point is a multi-gap cylinder, a.k.a. the RQ
or the TCBOR gap.

>RF CHOKES
>do i really need them?
>whats a good Mh/Uh

You will no doubt get several different answers to this.  I say no,
chokes in a protection network eliminate one problem (they're good at
filtering out the tank frequency) but create another comparable problem
(they will ring at their own self-resonant frequency).  Instead, use just
an R-C network in each leg of the NST.  C=300-800pF in parallel with
safety gap, R=1K-10K, 50-100W between NST terminal and main spark gap.

Regards, Gary Lau
Waltham, MA USA