I am using Reg's programs to calculate the Q and R of 'large'. These coils are
in the range of 220 mm in diameter and long.

There seems to be a difference in the coil simulation between Vertload and
c_poise. In particular c_poise seems more sensitive to coil wire diameter then
vertload. Vertical load will create a coil with low R and a relativily small
wire diameter and pitch, 2 mm and .2 pitch (it does not predict Q). C_poise
requires a large wire diameter, 12 mm and a high pitch, .8 to achieve similar R
values.

Is there a reason for this? Am I missing something?

Is there a way to simulate Q and R for these coils with nec?? How would one
create an nec representation for a coil?

Thanks - Dan - kb0qil

Frank,

I am stuck with the GH descriptor. Do you have a tool that can generate a
description of a coil 250x250 mm with 22 turns of 12 mm tubing?

Is it as simple as doing the division and filling in the entries?

Thanks - Dan

Frank wrote:
"GH" should do it Dan. I also did a Mathcad analysis based on Terman. If
you have Mathcad I can send it to you. One thing I should do is compare NEC
with Terman.

Frank


"dansawyeror" wrote in message
. ..

I am using Reg's programs to calculate the Q and R of 'large'. These coils
are in the range of 220 mm in diameter and long.

There seems to be a difference in the coil simulation between Vertload and
c_poise. In particular c_poise seems more sensitive to coil wire diameter
then vertload. Vertical load will create a coil with low R and a
relativily small wire diameter and pitch, 2 mm and .2 pitch (it does not
predict Q). C_poise requires a large wire diameter, 12 mm and a high
pitch, .8 to achieve similar R values.

Is there a reason for this? Am I missing something?

Is there a way to simulate Q and R for these coils with nec?? How would
one create an nec representation for a coil?

Thanks - Dan - kb0qil

Try this Dan:

CM Inductor Q Calculation
CE
GH 1 500 10 200 100 100 100 100 2.5
GW 2 5 100 0 200 0 0 200 2.5
GW 3 10 0 0 200 0 0 0 2.5
GW 4 5 0 0 0 100 0 0 2.5
GS 0 0 0.001000
GE 0
EX 0 3 5 00 1 0
FR 0 9 0 0 3.7 0.025
LD 5 1 1 520 5.7001E7
RP 0 181 1 1000 -90 90 1.00000 1.00000
EN

I am sure you need to fine tune the structure, since I just guessed at the
wire diameter at 5 mm for #4. Also not sure what you mean by "Pitch". This
coils shows a Q of 2600 at 3.8 MHz. Don't know how 4Nec2 will handle it,
but you could end up with 520 tags!

73,

Frank


"Frank" wrote in message
news:8OPHf.9448$W31.154@edtnps90...
"GH" should do it Dan. I also did a Mathcad analysis based on Terman. If
you have Mathcad I can send it to you. One thing I should do is compare
NEC with Terman.

Frank


"dansawyeror" wrote in message
. ..
I am using Reg's programs to calculate the Q and R of 'large'. These coils
are in the range of 220 mm in diameter and long.

There seems to be a difference in the coil simulation between Vertload
and c_poise. In particular c_poise seems more sensitive to coil wire
diameter then vertload. Vertical load will create a coil with low R and a
relativily small wire diameter and pitch, 2 mm and .2 pitch (it does not
predict Q). C_poise requires a large wire diameter, 12 mm and a high
pitch, .8 to achieve similar R values.

Is there a reason for this? Am I missing something?

Is there a way to simulate Q and R for these coils with nec?? How would
one create an nec representation for a coil?

Thanks - Dan - kb0qil

Ok Dan, posted a response before I saw your comments. Getting a bit late
here, but will try your dimensions tomorrow.

Frank


"dansawyeror" wrote in message
...
Frank,

I am stuck with the GH descriptor. Do you have a tool that can generate a
description of a coil 250x250 mm with 22 turns of 12 mm tubing?

Is it as simple as doing the division and filling in the entries?

Thanks - Dan

Frank wrote:
"GH" should do it Dan. I also did a Mathcad analysis based on Terman.
If you have Mathcad I can send it to you. One thing I should do is
compare NEC with Terman.

Frank


"dansawyeror" wrote in message
. ..

I am using Reg's programs to calculate the Q and R of 'large'. These
coils are in the range of 220 mm in diameter and long.

There seems to be a difference in the coil simulation between Vertload
and c_poise. In particular c_poise seems more sensitive to coil wire
diameter then vertload. Vertical load will create a coil with low R and a
relativily small wire diameter and pitch, 2 mm and .2 pitch (it does not
predict Q). C_poise requires a large wire diameter, 12 mm and a high
pitch, .8 to achieve similar R values.

Is there a reason for this? Am I missing something?

Is there a way to simulate Q and R for these coils with nec?? How would
one create an nec representation for a coil?

Thanks - Dan - kb0qil

Hi Dan, Try the following code:

CM Inductor Q Calculation
CE
GH 1 500 11.36363636 250 125 125 125 125 5
GW 2 5 125 0 250 0 0 250 5
GW 3 10 0 0 250 0 0 0 5
GW 4 5 0 0 0 125 0 0 5
GS 0 0 0.001000
GE 0
EX 0 3 5 00 1 0
FR 0 3 0 0 3.7 0.1
LD 5 1 1 520 5.7001E7
RP 0 181 1 1000 -90 90 1.00000 1.00000
EN

Note that a detailed description of the "GH" fields are on page 20 of the
"NEC - 2, Part III: User's Guide"; on page 20. The guide can be obtained at
http://www.nec2.org/other/nec2prt3.pdf and is only just over 400 kB.

The coil dimensions you gave me are not physically realizable since 22 turns
of 12 mm diameter wire will result in a coil length of 264 mm. I have
therefore revised the wire radius to 5 mm. NEC will return an error if I
attempt to input a radius of 6 mm.

NEC indicates the coil is 123 uH, and a Q of 4471 at 3.8 MHz. You would
certainly have to silver plate the coil in order to maintain such a Q. The
formation of copper oxide will cause Q degradation over time -- despite what
some people seem to think.

I have thought of building hi-Q inductors with 1/4" copper pipe, but not
sure how you can do the same with 1/2" pipe as it must be very difficult to
bend.

Before building an antenna with such loaded radials I think it would be
interesting to model it with non-loaded radials, and compare it with a
"Lumped element" loading coil analysis.

73,

Frank



"dansawyeror" wrote in message
...
Frank,

I am stuck with the GH descriptor. Do you have a tool that can generate a
description of a coil 250x250 mm with 22 turns of 12 mm tubing?

Is it as simple as doing the division and filling in the entries?

Thanks - Dan

Frank wrote:
"GH" should do it Dan. I also did a Mathcad analysis based on Terman.
If you have Mathcad I can send it to you. One thing I should do is
compare NEC with Terman.

Frank


"dansawyeror" wrote in message
. ..

I am using Reg's programs to calculate the Q and R of 'large'. These
coils are in the range of 220 mm in diameter and long.

There seems to be a difference in the coil simulation between Vertload
and c_poise. In particular c_poise seems more sensitive to coil wire
diameter then vertload. Vertical load will create a coil with low R and a
relativily small wire diameter and pitch, 2 mm and .2 pitch (it does not
predict Q). C_poise requires a large wire diameter, 12 mm and a high
pitch, .8 to achieve similar R values.

Is there a reason for this? Am I missing something?

Is there a way to simulate Q and R for these coils with nec?? How would
one create an nec representation for a coil?

Thanks - Dan - kb0qil

On Mon, 13 Feb 2006 13:41:24 GMT, "Frank"
wrote:

NEC indicates the coil is 123 uH, and a Q of 4471 at 3.8 MHz. You would
certainly have to silver plate the coil in order to maintain such a Q. The
formation of copper oxide will cause Q degradation over time -- despite what
some people seem to think.

It is not just what "some people" think.

Check out: http://k6mhe.com/n7ws/Plating.pdf

73,
Danny, K6MHE



email: k6mheatarrldotnet
http://www.k6mhe.com/

Thank you. I will use this to figure out how to do this manually.

You are correct about the wire. Reg's program predicted 9mm not 12. I copied the
wrong number. 22 turns of 9mm tubing is correct. I am not sure how physically
realizable that number is.

Dan

Frank wrote:
Hi Dan, Try the following code:

CM Inductor Q Calculation
CE
GH 1 500 11.36363636 250 125 125 125 125 5
GW 2 5 125 0 250 0 0 250 5
GW 3 10 0 0 250 0 0 0 5
GW 4 5 0 0 0 125 0 0 5
GS 0 0 0.001000
GE 0
EX 0 3 5 00 1 0
FR 0 3 0 0 3.7 0.1
LD 5 1 1 520 5.7001E7
RP 0 181 1 1000 -90 90 1.00000 1.00000
EN

Note that a detailed description of the "GH" fields are on page 20 of the
"NEC - 2, Part III: User's Guide"; on page 20. The guide can be obtained at
http://www.nec2.org/other/nec2prt3.pdf and is only just over 400 kB.

The coil dimensions you gave me are not physically realizable since 22 turns
of 12 mm diameter wire will result in a coil length of 264 mm. I have
therefore revised the wire radius to 5 mm. NEC will return an error if I
attempt to input a radius of 6 mm.

NEC indicates the coil is 123 uH, and a Q of 4471 at 3.8 MHz. You would
certainly have to silver plate the coil in order to maintain such a Q. The
formation of copper oxide will cause Q degradation over time -- despite what
some people seem to think.

I have thought of building hi-Q inductors with 1/4" copper pipe, but not
sure how you can do the same with 1/2" pipe as it must be very difficult to
bend.

Before building an antenna with such loaded radials I think it would be
interesting to model it with non-loaded radials, and compare it with a
"Lumped element" loading coil analysis.

73,

Frank



"dansawyeror" wrote in message
...

Frank,

I am stuck with the GH descriptor. Do you have a tool that can generate a
description of a coil 250x250 mm with 22 turns of 12 mm tubing?

Is it as simple as doing the division and filling in the entries?

Thanks - Dan

Frank wrote:

"GH" should do it Dan. I also did a Mathcad analysis based on Terman.
If you have Mathcad I can send it to you. One thing I should do is
compare NEC with Terman.

Frank


"dansawyeror" wrote in message
om...


I am using Reg's programs to calculate the Q and R of 'large'. These
coils are in the range of 220 mm in diameter and long.

There seems to be a difference in the coil simulation between Vertload
and c_poise. In particular c_poise seems more sensitive to coil wire
diameter then vertload. Vertical load will create a coil with low R and a
relativily small wire diameter and pitch, 2 mm and .2 pitch (it does not
predict Q). C_poise requires a large wire diameter, 12 mm and a high
pitch, .8 to achieve similar R values.

Is there a reason for this? Am I missing something?

Is there a way to simulate Q and R for these coils with nec?? How would
one create an nec representation for a coil?

Thanks - Dan - kb0qil

"Dan Richardson" wrote in message
...
On Mon, 13 Feb 2006 13:41:24 GMT, "Frank"
wrote:

NEC indicates the coil is 123 uH, and a Q of 4471 at 3.8 MHz. You would
certainly have to silver plate the coil in order to maintain such a Q.
The
formation of copper oxide will cause Q degradation over time -- despite
what
some people seem to think.

It is not just what "some people" think.

Check out: http://k6mhe.com/n7ws/Plating.pdf

73,
Danny, K6MHE

Thanks Danny, Interesting paper. It certainly points out problems with
silver plating. I must say I have never attempted to measure the Qs of
inductors with and without plating, but it is something to think about. My
point was more about the effects of copper oxide on inductor Q. It makes me
think that the best way to prevent the build up of oxide is to use some kind
of low-loss insulating material on the surface of the copper.

73,

Frank

Frank wrote:
Thanks Danny, Interesting paper. It certainly points out problems with
silver plating. I must say I have never attempted to measure the Qs of
inductors with and without plating, but it is something to think about. My
point was more about the effects of copper oxide on inductor Q. It makes me
think that the best way to prevent the build up of oxide is to use some kind
of low-loss insulating material on the surface of the copper.

The problem is that copper oxide isn't necessarily what forms on copper
-- you can have copper chloride, sulfide, oxide, and perhaps other salts
in various combinations and thicknesses depending on the environment.
Likewise, silver will form all those salts.

If a chemical coating is a very poor conductor or a very good conductor,
it won't appreciably degrade the Q. What will degrade the Q is a coating
of sufficient thickness of an intermediate conductivity. I've tried for
years to find data on the various salts of both metals, and found only
very few.

But here's a quote from Chipman (_Theory and Problems of Transmission
Lines_, 1968, p.81 - thanks to Wes, N7WS!):

"For many years it was thought that silver was necessarily the best
plating material, since silver has the highest conductivity of all
metals. However, careful measurements have shown that the corrosion
products on a silver surface in ordinary atmospheres have intermediate
conductivity, while those on a copper surface have very low
conductivity. The result is that high frequency currents in a copper
conductor flow almost entirely in the copper, below the surface
corrosion layers, and the conductor's effective conductivity is that of
the copper. For a silver conductor, on the other hand, an appreciable
fraction of the current flows in the corrosion material of intermediate
conductivity (the corrosion products are generally oxides and sulfides)
and the effective conductivity of the conductor as a whole may be
substantially less than that of silver. If a silver surface is protected
against corrosion, including oxidation, by an extremely thin layer of
plated or evaporated gold or by a low-loss dielectric coating, a silver
plated conductor will have the lowest possible distributed resistance."

Chipman is obviously assuming a pure silver plating. As Danny's posted
paper (http://k6mhe.com/n7ws/Plating.pdf) points out, "silver" platings
are seldom pure silver, and are usually considerably less conductive
than copper to begin with.

So it's been known for at least several decades that silver plating
degrades Q over the long run, for a couple of reasons. But myths die hard.

Incidentally, I've found a couple of errors in the equations in the
Fowler paper Danny posted (and which Wes N7WS kindly sent me years ago),
apparently made during the copying of the original equations from their
source. There seem to be some additional errors which I can't identify.
If anyone knows where I might get a copy of the paper with the original
equations, which is reference 10 (Astbury) in the Fowler paper, I'd be
very appreciative. I've requested a copy of the paper through the local
library, but it's likely to take a very long time to get. Perhaps some
of the U.K. readers can make a suggestion, since the I.E.E. is the
British equivalent of our I.E.E.E. I see from the I.E.E. web site that
they're in the process of getting their older journals on line, but
haven't finished the task. I don't mind at all paying a fee for it.

Roy Lewallen, W7EL

Frank wrote:
It makes me
think that the best way to prevent the build up of oxide is to use some kind
of low-loss insulating material on the surface of the copper.

Magnet wire comes to mind.
--
73, Cecil http://www.qsl.net/w5dxp