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Re: Questions Questions

Subject: 
        Re: Questions Questions
  Date: 
        Fri, 28 Mar 1997 01:41:23 -0500 (EST)
  From: 
        richard hull <rhull-at-richmond.infi-dot-net>
    To: 
        Tesla List <tesla-at-pupman-dot-com>


At 09:04 AM 3/27/97 -0600, you wrote:
>Subject: 
>        Re: Questions Questions
>  Date: 
>        Thu, 27 Mar 1997 07:49:54 -0500 (EST)
>  From: 
>        msr7-at-po.cwru.edu (Mark S. Rzeszotarski, Ph.D.)
>    To: 
>        Tesla List <tesla-at-pupman-dot-com>
>
>
>Hello Coilers,
>         "George W. Ensley" <erc-at-coastalnet-dot-com> wrote in part:
>>> I have been attempting to optimize my 6" coil with some success. What i
>>> have
>>> noticed is that the coupling coefficient seems to vary a good deal. Any
>>> number of factors seem to affect it, breakout, toroid height, toroid
>>> size,
>>> coil height, etc. I am using K=(Fh-Fl)/Fr to find K is this correct?
>>
>>
>        Coupling is dependent only on the geometry between the primary
>and
>secondary.  As sparks start to break out, however, the load impedance
>the
>primary sees changes considerably.
>        Here is another method to measure K iIf an inductance meter is
>available,  Connect up your meter to the primary with the secondary in
>its
>proper position for normal operation.  Disconnect all leads to the
>secondary
>(including ground).  Measure the primary coil inductance with the
>secondary
>coil open circuited, and call it Lpso.  Next, short circuit the
>secondary
>windings using a small piece of wire extending from the top of the
>secondary
>to the bottom.  Again, measure the primary coil inductance, and call it
>Lpss.  One can now compute the coupling coefficient k using the formula:
>
>       k = SQRT [ 1.0 - (Lpss / Lpso) ]  
>where SQRT means take the square root.
>
>        As an aside, Tesla measured mutual inductance by using the
>available
>A.C.  power.  He ran straight A.C. power into the primary using a lamp
>for
>current limiting, and carefully measured the induced voltage in the
>secondary.  Most inductance meters use a similar low frequency to
>determine
>inductance, using a bridge arrangement.
>
>Regards,
>Mark S. Rzeszotarski, Ph.D.
>
>

All,


The method Dr. Mark shows above is the only method we use here in
Richmond
and works incredibly well.  We have shown it in practice on our tapes. 
It
is "Q&D" (quick and dirty),  works well in the hands of an idiot, and
gives
good solid results.  You should have a very good LCR meter and have all
toroid's and coils in their actual firing positions.    By the way,...
The
equation also works for the secondary being measured and the primary
opened
and shorted. 

Richard Hull,TCBOR