- View SourceJohn,Litz wire reduces the impact of the skin effect and the proximity effect. So for a piratical explanation I have just wound a 18 turn coil with standard solid 18 gage wire, close wound, on a 7.5" FSL and I find the tuning range (using a 10 to 381 pf variable capacitor) is 1200 to 400 KHz. Now I rewind a 18 turn coil, close wound, on the same 7.5" FSL using 660/46 Litz wire, and I now find the tuning range is 1850 to 405 KHz. So my question to you is if it is not higher
**distributed capacitance**using the solid wire over that of the Litz wire, then what is it that is causing the frequency, at the high end of the band to be lower and having less tuning range? This is not theory, this is what I see from a piratical stand point. I am sure that if you want the theory behind it you can find it somewhere here on the web. (I am not skeptical, I am a believer)EverettIn a message dated 1/5/2013 11:25:00 P.M. Central Standard Time, jpopelish@... writes:On 01/05/2013 09:15 PM, everettsharp@... wrote:

> Hi John,

>

> It probably does not mean anything if you have enough space between the

> turns, but when you have the windings next to each other, then distributed

> capacitance does become a major factor. Blitz wire does have less distributed

> capacitance when the windings are butted up next to each other, then does

> standard wire.

I didn't know that. Is this a fact you have measured, or a

claim you have read, somewhere? (I'm sceptical.)

--

Regards,

John Popelish - View SourceOn 01/06/2013 01:08 PM, everettsharp@... wrote:
> jpopelish@... writes:

(snip)

>> (mailto:everettsharp@...) wrote:

>>> Litz wire reduces the impact of the skin effect and

>>> the proximity effect. So for a piratical explanation

>>> I have just wound a 18 turn coil with standard solid

>>> 18 gage wire, close wound, on a 7.5" FSL and I find

>>> the tuning range (using a 10 to 381 pf variable

>>> capacitor) is 1200 to 400 KHz. Now I rewind a 18 turn

>>> coil, close wound, on the same 7.5" FSL using 660/46

>>> Litz wire, and I now find the tuning range is 1850

>>> to 405 KHz. So my question to you is if it is not

>>> higher distributed capacitance using the solid wire

>>> over that of the Litz wire, then what is it that is

>>> causing the frequency, at the high end of the band

>>> to be lower and having less tuning range? This is

>>> not theory, this is what I see from a piratical stand

>>> point. I am sure that if you want the theory behind

>>> it you can find it somewhere here on the web. (I am

>>> not skeptical, I am a believer)

>

Here is what I am thinking about, with regard to comparing

>> One more question. Was the length (across the turns)

>> of the 18 turn Litz coil the same as the length of the

>> 18 turn solid wire coil? In other words, was the 18

>> gauge solid wire the same width as the (as wound) Litz

>> wire?

> I don't know what the length was of the two wires, as I

> did not measure them. However, the cross section area

> of 660/46 Litz wire is nearly the same as solid 18 gage

> wire.

Litz to solid (or any other two choices of winding conductor.

As long as the resonant Q of a the inductance of a loop and

with its own stray capacitance and a tuning capacitor allows

some actual math solutions, if two tuning cap values and two

resonant frequencies are available from an experiment, it

should be possible to calculate the actual coil inductance

and effective, parallel, stray capacitance. The additional

requirement is that, either the resonant Q is about 10 or

higher, so the losses do not appreciably affect the resonant

frequencies, or the effective losses must be calculable for

the for the loop at the two resonant frequencies.

The point being, that with a given coil, and two resonant

frequencies, with two values of tuning capacitance, it

should be possible to calculate the loop inductance and loop

stray capacitance, by solving a pair of simultaneous

equations for each coil.

So, it should be possible with these two resonant

frequencies, per coil, with two values of tuning

capacitance, we should be able actually solve for any coil's

actual inductance and stray capacitance.

This technique should be handy to compare any two different

construction choices (diameter, turn spacing, conductor

strands, wire insulation, form material, etc.) to work

toward an optimum (widest tuning range per dollar, highest Q

per dollar, or whatever figure of merit you choose) design

for any available coil conductor material and construction

technique.

This solution rapidly takes coil design optimization out of

the opinion phase and moves it into experimental science.

--

Regards,

John Popelish