Re: Tuning by current mea

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 Te> From Esondrmn-at-aol-dot-com Tue Apr  4 16:21 MDT 1995
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 Te> 15:59:24 -0600
 Te> Date: Tue, 4 Apr 1995 17:59:05 -0400
 Te> From: Esondrmn-at-aol-dot-com
 Te> To: mark.graalman-at-mediccom.norden1-dot-com
 Te> Cc: tesla-at-grendel.objinc-dot-com
 Te> Subject: Tuning by current measurement

 Te> cc: tesla-at-grendel.objinc-dot-com

 Te> Mark,

 Te> Thanks for the recent posting on measuring secondary current.  My
 Te> interest in this is to get a better idea of where my sharpest tuning
 Te> point is.  My system should be high Q.  I have it spaced up off the
 Te> floor on plastic, I used plastic mounts for my primary (3/8" copper
 Te> tubing), moved my RF filters back away from the primary, shortened my
 Te> ground paths, etc. - everything that should result in a high Q but I am
 Te> having a difficult time finding a nice sharp tuning point by trying to
 Te> guage the longest discharge.  Also, I don't have an oscilloscope
 Te> available. 
 Te> I would appreciate more commentary on this subject.

 Te> Thanks,  Ed Sonderman

 MG> Ed, I don't know how many turns you have on your primary, or what your
     level of pri/sec coupling is, but if you have heavy coupling and alot
     of turns in the primary the resulting power transfer to the secondary
     can be so high that small errors in the primary frequency will go
     un-noticed. Others may argue this, but to be quite honest as far as
     tuning the primary coil is concerned, I do the following and it has
     always been accurate enough that further tuning other than spark gap
     and slight coupling adjustments offer little benefit. I attach a 100K
     ohm carbon resistor to the side of the toroid and then to end of the
     resistor I attach a #30 wire of a length equal to the appoximate length
     of the discharge, and run it out horizontally from the toroid and attach
     it to a insulated support. In other words, the wire/ resistor act as the
     discharge arc. Then I measure the frequency of the secondary coil with a
     scope and generator. I then remove the secondary coil from the vicinity
     of the primary and tune the primary circuit frequency to match that of
     the secondary. It has never been off by more than about 1/4 turn on the
     primary tap placement. By the way, I usually use a pri/sec coupling of
     about .15 as a starting point.

                                Mark Graalman TCBA# 1399

... Alias, Mark the spark
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