Re: AC wire resistance with proximitry effects

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi Bart,

This is very believable.  The Medhurst correction was around 3 
(iirc). My Q calculation without proximity effects was about 600 so 
that would make the "real" Q about 200.  I will measure the Q soon 
for closure.  It sounds like having wire diameter >= 5sd isn't 
important for good Q (my coil has diam = 2.5 sd).   Maybe we ought to 
replace the wire size recommendation in JavaTC with the Fraga 
resistance and Q predictions and leave it to the designer to choose 
the best tradeoffs.

Gerry R


> Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
>
> Hi Gerry,
>
> Fraga is looking "real".  Have you checked your coils predictions 
> with Fraga? I'm showing a Q of 207. My high turn 8.5" coil is 
> showing a Q of 155. If memory serves, that's close to measurement. 
> I'm trying to dig up my misc. Q measurements (scattered via emails, 
> hand written notes, etc.). Anyway, could only get on the internet 
> for a second, but wanted to mention that. I still need to do a lot 
> of verification with the equation and values as I did it rather 
> quickly. But, it certainly ballparked well.
>
> Take care,
> Bart
>
> Tesla list wrote:
>
> > Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
> >
> > Hi Bart,
> >
> > After looking at the Fraga equation again, it does look and L and C 
> > directly. It uses the product of L and C by virtue of the frequency 
> > needed for skin depth.  Your Les and Ces are the frequency 
> > determining equivalents that are suppose to be accurate to like 
> > 1%.  How accurate are Medhurst C and Wheeler L in predicting the 
> > correct frequency.  I doubt there will be any significant 
> > difference especially since f gets sqrt'd which will cut the error in half.
> >
> > Gerry R.
> >
> > > Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
> > >
> > > Also, with Fraga, Gary used Medhurst C and L. I wonder how it 
> > > plays out with Ces and Les in place of Medhurst? As a matter of 
> > > fact, I wonder how well a lumped effective L and C would work with 
> > > all the equations? They probably won't change a great deal (but, I 
> > > haven't looked at that).
> > >
> > > Take care,
> > > Bart