With millions of other subscribers world-wide, I am receiving as many as 250
spam messages daily, many generated by viruses in other people's computers.

99 perecent of this attrocious rubbish originates in the United States of
America, the land of the free.

Can't you get Bush to do something about it?

I can do no better than speed-read the subject lines and dump everything
unless the subject matter is OBVIOUSLY something of interst to me.

SWR or Old Wives is OK

Female or male teenagers at my time of life are not.
---
.................................................. ..........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. ..........

Reg Edwards wrote:
I can do no better than speed-read the subject lines and dump everything
unless the subject matter is OBVIOUSLY something of interst to me.

Reg, does your software involving loading coils take distributed
coil capacitance into account? Is there some rule of thumb involved?
--
73, Cecil, W5DXP

Cec,

I thought you'd never ask. ;o)

Regarding solenoidal, single-layer, antenna loading coils -


Rule 1.

Inductance cannot change with frequency. With ANY coil, inductance between
the end points depends solely on dimensions and number of turns. As you
know, calculating formulae can be found almost anywhere. But to be very
exact with a long coil, an appreciable fraction of a wavelength, add the
inductance of a straight wire of the same length. After all, the coil may
consist of less than one turn as occurs when a coarse helix of wire is
pulled out straight. For a demonstration use program SOLNOID3. Read the
notes.


Rule 2.

Self-capacitance of a multi-turn, fairly close-wound coil consists of two
parts, Ca and Cb, both of which can be considered to be in shunt with the
coil to form a parallel tuned circuit. The structure does in fact behave
like this and has a measurable resonant frequency.


Ca is the same as the capacitance between the two halves of a dipole of the
same overall length and diameter as the coil. Matters become very
complicated as the spacing between turns increases


Cb is the capacitance between N adjacent turns ALL IN SERIES with each
other. So as N increases the resultant fast becomes very small. As spacing
between turns increases Cb decreases even faster. This is intuitively true.


All the above is calculable from dimensions. As is done in LOADCOIL and some
other programs. I'm sure somebody will let me know if a significant error
is found.


Sorry I am unable to provide references. I doubt if there are any. I have
made measurements.


Why not ask Yuri ? He sounds like an expert.
----
.................................................. ..........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. ..........

=========================================

"Cecil Moore" wrote
Reg, does your software involving loading coils take distributed
coil capacitance into account? Is there some rule of thumb involved?
--
73, Cecil, W5DXP

Cecil,

There's a little check you can make on the accuracy of program SOLNOID3
regarding the self-resonant frequency of a solenoid.


The resonant frequency is due to the stray capacitance of the coil being in
shunt with the inductance.


The program allows the length of a coil to be stretched out until it is as
long as the wire it was wound with. Throughout the process, as L and C
change with coil length, the self-resonant frequency is calculated.


Resonant frequency is calculated up to the point when the original N turns
are stretched out into a straight length of wire. You can do a simple check
using your space-man's pocket calculator.


Does the program-calculated resonant frequency coincide with the resonant
frequency of the straight wire considered as a 1/2-wave dipole ?


Incidentally, when the coil is only partly stretched out, the program can be
used to estimate the resonant frequency of "Slinky's". Never having had a
Slinky I cannot say precisely how accurate this might be.
----
Happy Xmas to you and yours and all that sort of thing.
----
Reg.

Reg Edwards wrote:
The resonant frequency is due to the stray capacitance of the coil being in
shunt with the inductance.

Hi Reg, that answers my question. I'm glad you didn't go the
"lumped" route. Do you have a program that calculates the delay
through a real-world coil?

Incidentally, when the coil is only partly stretched out, the program can be
used to estimate the resonant frequency of "Slinky's". Never having had a
Slinky I cannot say precisely how accurate this might be.

Did you take into account that some Slinky's are made out of
plastic. :-)
--
73, Cecil, W5DXP

"Reg Edwards" wrote in message
With millions of other subscribers world-wide, I am receiving as many as
250
spam messages daily, many generated by viruses in other people's
computers.

99 percent of this atrocious rubbish originates in the United States of
America, the land of the free.

Can't you get Bush to do something about it?

Very Funny! In the States most of the Spam comes from your side of the
pond, or from .TW or China! They relay it through someone else!
Blocking helps some, but nothing works for all if it!

On Fri, 12 Dec 2003 19:45:42 GMT, "Roger Gt"
wrote:


"Reg Edwards" wrote in message
With millions of other subscribers world-wide, I am receiving as many as
250
spam messages daily, many generated by viruses in other people's
computers.

99 percent of this atrocious rubbish originates in the United States of
America, the land of the free.

Can't you get Bush to do something about it?

Very Funny! In the States most of the Spam comes from your side of the
pond, or from .TW or China! They relay it through someone else!
Blocking helps some, but nothing works for all if it!


Yep, here in the US we are busy as beavers making Chinese, Korean and
Brazilian (Portugese) spam. On the other hand, the Commonwealth of
Virginia indicted two North Carolina men for violating VAs anti-spam
law. One has been arrested and extradited and the other is
surrendering.

Russ

On Fri, 12 Dec 2003 14:19:08 +0000 (UTC), "Reg Edwards"
wrote:

With millions of other subscribers world-wide, I am receiving as many as 250
spam messages daily, many generated by viruses in other people's computers.

99 perecent of this attrocious rubbish originates in the United States of
America, the land of the free.

Can't you get Bush to do something about it?


No, we were hoping The Queen could kill it at the shoreline
for you.

Frankly most of my spam comes from Brazil.

On Fri, 12 Dec 2003 14:19:08 +0000 (UTC), "Reg Edwards"
wrote:

With millions of other subscribers world-wide, I am receiving as many as 250
spam messages daily, many generated by viruses in other people's computers.

99 perecent of this attrocious rubbish originates in the United States of
America, the land of the free.

Can't you get Bush to do something about it?

I can do no better than speed-read the subject lines and dump everything
unless the subject matter is OBVIOUSLY something of interst to me.

SWR or Old Wives is OK

Female or male teenagers at my time of life are not.
---
................................................. ..........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
................................................. ..........

Isn't Spam just plain a pain.. our Server here use a company named
Postini (do a google search) contact your Local server and tell them
you would like this feature to be added.. Postini filters all my
incoming mail and stops 98 percent of the spam before it's downloaded
to my computer. It also has Virus checking so the 200 or so viruses
i've been getting each week have been stopped before it's downloaded
on my machines. It would be a worthwhile investment even if I had to
pay a little extra for the service. Instead of looking through tons
of email to determine what is spam, I just go to the message center
and look a the list of blocked headers and tell it to deliver only the
ones I want .. or I can read the message there first.

Check it out.

Also most of the spam I'm receiving here seems to originate from China
or the far east. But most of the viruses unfortunately are coming
(mostlikely unknown to the actual person,) from other hams in the U.S.
who just won't keep their machines virus programs updated. I long ago
stopped reporting them cause it did no good and just used up too much
of my time.. Just block them now..

Cheers ,
73 Dave

Reg Edwards wrote:

With millions of other subscribers world-wide, I am receiving as many as 250
spam messages daily, many generated by viruses in other people's computers.

99 perecent of this attrocious rubbish originates in the United States of
America, the land of the free.


hmm, most of my spam originates from members of newsgroups that have a
computer infected with Swen virus. The rest appears to originate in the
far east.

Which brings up the thought: Guys and Gals, check out your computer to
see if it is infected! If you are using a Winbox, using Outlook in one
of it's incarnations, Internet Explorer, and haven't updated for a
couple years, guess what?


- Mike KB3EIA -