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Re: More Coupling...



Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-uswest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Marco, All, 

Marco, thanks for identifying your coupling measurements. I did the same with
yours as with others but it was tedious as you have values in cm that I had to
convert to inches then back to meters (inches to model in JavaTC to obtain near
correct values for acmi). 

The primary dimensions I had to kind of guess at looking at your photos
(detailed dimensions were not available, but inductance was). I realized early
on that you measured coupling using the entire primary turns and not at the
point you would tune at for the 0.1uF cap you use, otherwise the inductance and
K would have been been different. This is just fine, but wanted to point that
out for everyone. 

This is kind of interesting to me. We have heard at times that BIG COILS can
get away with running at higher coupling values than smaller coils. If I was to
take a look at your K values you measured, I would think "ok, not really
different than what I've seen lately", but if you tap at about 8 turns (approx.
tune point for 0.1uF, maybe a little less), the value of K increases by about
0.027. So for a base line of zero, you measured 0.169, but add 0.027 to it and
baseline is at a K of 0.196! Marco, your running at higher K values than you
measured for the height assuming main components have not changed. You probably
already know this, but thought I'd throw that out for everyones benefit. 

Here's the data acmi spit out: 
(note, height is converted to inches, rounded 3 decimals). 

acmi values for Ls=80.3mH, Lp=104uH 
Marco's measured values are Ls=80.221mH, Lp=103.8uH 

height     acmi    marco 
(inch)      K        K      delta    err% 
5.8661    0.225    0.229    0.004    1.78 
5.1969    0.219    0.223    0.004    1.83 
3.622     0.204    0.207    0.003    1.47 
2.0079    0.187    0.189    0.002    1.07 
0.3937    0.169    0.169    0.0      0 
-1.1811   0.150    0.148    0.002    1.33 
-2.8165   0.132    0.129    0.003    2.27 
-4.2913   0.118    0.112    0.006    5.08 
-5.0787   0.107    0.105    0.002    1.87 

Note about error %: This is based on quantity. For example, 0.001 delta is huge
to a K of 0.050 and small to a K of 0.250. This is how Paul was basing the
amount of error the program varies from measurement so I've chosen to display
both for everyones benefit. 

I'll start putting info up on a web page instead of displaying to the list from
now on as more data comes in to save some TL bandwidth (unless there is a cry
for this data to be posted here). If something odd occurs with certain coils,
I'll post back. 

Happy Holidays, 
Bart 

PS: If you find yourself bored this holiday season - <hint> measure K <grin> I
dont' have any smaller coil measurements. 
  
  
  
  
  
  
  
  
  
  
  
  
  
  

Tesla list wrote: 
>
> Original poster: "Marco Denicolai by way of Terry Fritz
> <twftesla-at-uswest-dot-net>" <Marco.Denicolai-at-tellabs.fi> 
>
> Hi Bart. 
>
> I have measured some time ago Thor's coupling coeff. and reported my 
> results at: 
>
>
> <http://www.saunalahti.fi/dncmrc/th_ccoef.htm>http://www.saunalahti.fi/dnc
> mrc/th_ccoef.htm 
>
> I can't recall if Paul has already used my data or not. 
> The measure was taken by first measuring Lprimary and Lsecondary, then 
> Lprimary+secondary (in series) at different primary height. 
> >From that M was derived and then k. 
>
> I got a pretty linear curve: the little curvature near k=0.12 is probably 
> due to 
>  the fact that I was forced to change a connection lead for 
> that measurement point. 
>
> Regards 
>
> "Tesla list" <tesla-at-pupman-dot-com> on 22.12.2000 04:28:02 
>
> To:   tesla-at-pupman-dot-com 
> cc:    (bcc: Marco Denicolai/MARTIS) 
> Subject:  Re: More Coupling... 
>
> Original poster: "Barton B. Anderson by way of Terry Fritz 
> <twftesla-at-uswest-dot-net>" <tesla123-at-pacbell-dot-net> 
>
> Hi Paul and Everyone, 
>
> My reply here is to ask (plead) for more coiers to make coupling
> measurements. 
> All that is needed is a DMM capable of volt and amp readings (or meters
> capable 
> of this). Also needed is a primary that can be moved above and below the 
> secondary base line in steps (or the secondary to achieve the same result). 
> Measurement is easy (we can define that later). 
>
> If case you haven't kept up with this thread, I have found an increase in 
> coupling error to Paul's program "acmi" predictions (error increases in the 
> direction of increased coupling). What I would like to find out with your
> help 
> is: 
>
> 1. is current changing during measurement (and not realized), 
> 2. is the flat primary shape causing the error, 
> 3. if #2 is correct, does acmi need to apply a correction of some type, 
> 4. if #3, is this true for only flat primary's? 
> 5. Lot's of other little tid bits to increase our coupling knowledge. 
>
> So we need some flat, helical, and conical coupling measurements as well.
> This 
> type of comparison has been needed for some time and the information will add
>
> another little wrinkle in our coiling brains. 
>
> Any takers? Anyone? 
>
> Thanks, 
> Bart