On Wed, 01 Jun 2005 09:15:05 -0500, Cecil Moore
wrote:

I've added a Smith Chart graphic to my All-HF-Band-No-Tuner-Antenna
information on my web page.

I finally got to see the picture. Earlier, it loaded so slowly I only
got to see the top 10% after ten minutes or so.

If i read it correctly, you are saying that by adjusting the feedline
length, you have a 50 match at any band.

It sounds like this antenna and feed match....

http://www.qsl.net/w5dxp/notuner.htm


--
73 for now
Buck
N4PGW

I can honestly say I've never used a Smith Chart in anger in the whole
of my life.

Never had one in my possession for more than a minute just to inspect
it. Or by chance came across a condensed version in a book.

And I've worked on and with transmission lines from 0.1 Hz to 3000
MHz. At frequencies at which the Smith Chart is misleading and
useless.

I just didn't attend the same school as you lot.

It's habit forming like alcohol, tobacco and women. You can't think
straight without one in front of you. ;o)

But I do appreciate the love and respect you all have for it.
----
Reg.

Buck wrote:
Cecil Moore wrote:
I've added a Smith Chart graphic to my All-HF-Band-No-Tuner-Antenna
information on my web page.

I finally got to see the picture. Earlier, it loaded so slowly I only
got to see the top 10% after ten minutes or so.

QSL.NET is notoriously slow. I'm going to get a new web page supplier
one of these days.

If i read it correctly, you are saying that by adjusting the feedline
length, you have a 50 match at any band.

Close - by adjusting the feedline length, I have between a 25+j0 ohm
and a 100+j0 ohm "match" on any HF ham band. Any purely resistive
impedance between 25 ohms and 100 ohms will yield a 50 ohm SWR less
than 2:1. Most transmitters are satisfied with an SWR of less than
2:1. Any 450 ohm SWR between 4.5:1 and 18:1 (in the green zone) will
yield a 50 ohm SWR less than 2:1 if the proper length of feedline is
chosen.

It sounds like this antenna and feed match....

It is a tuned feeder that tunes the antenna system to resonance. To
get a 50 ohm SWR less than 2:1, the dipole needs to be 1/2 wavelength
on the lowest frequency of operation. That makes virtually all antenna
feedpoint impedances fall within the green target zone.

For instance, this feedline length adjustment will not work on a 102
ft. dipole (G5RV) used on 80m. The low R and high X causes the 450
ohm SWR to be higher than 18:1 so a 50 ohm SWR of 2:1 is impossible
without a tuner or network.

Here's the math:
450/18 = 25 ohms 50/25 = 2:1 SWR at current maximum point
450/4.5 = 100 ohms 100/50 = 2:1 SWR at current maximum point
--
73, Cecil http://www.qsl.net/w5dxp

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"Reg Edwards" wrote in message
...

I can honestly say I've never used a Smith Chart in anger in the whole
of my life.

Never had one in my possession for more than a minute just to inspect
it. Or by chance came across a condensed version in a book.

And I've worked on and with transmission lines from 0.1 Hz to 3000
MHz. At frequencies at which the Smith Chart is misleading and
useless.

I just didn't attend the same school as you lot.

It's habit forming like alcohol, tobacco and women. You can't think
straight without one in front of you. ;o)

But I do appreciate the love and respect you all have for it.
----
Reg.

Reg, you've aroused my curiosity on three points:

Why would you use 'Smith Chart' and 'anger' in the same sentence?

Why are there any frequencies where the Smith Chart is misleading and useless?
Which frequencies are they?

How can you say the Smith Chart is misleading and useless if you've never used
one, and never inspected one for more than a minute?

Walt, W2DU

On Thu, 2 Jun 2005 08:58:25 -0400, "Walter Maxwell"
wrote:

Why would you use 'Smith Chart' and 'anger' in the same sentence?

Hi Walt,

You've made the mistake of taking Reggie seriously for the wrong
points - but as it was by his design that you do so, you can be
forgiven. Walt, please note that all occurrences of "You" are meant
to apply to the general reader. Those general readers may now turn
their attention aside as I diverge into meaning, a dark arena few
enter fully prepared to emerge from.

As much as he rails about my "Shakespearian" language - style, nothing
else; his own - style that is - is as a Primitive. For many who have
little appreciation or training in the arts (writing being one of
them), being labeled a Primitive is not demeaning, it is merely
descriptive. As I offhandedly pointed out in another post, mine is a
Norman style to his Anglo-Saxon. The difference is not intelligence,
but persuasion. In other contexts, like religion, one might use the
word fundamentalist; hence the allusion drawn in the sentence you
responded to that ties together two disparate worlds as though the
association were an ethical choice. Reg could have as easily compared
varieties of wine to a Smith Chart - a gustatorial choice, but still a
primitive or fundamental balance. (Myself, to extend the metaphor of
religion, I would offer catholic choices.)

For either of us, if you simply divorce the style, content will
emerge, and I promise you find nothing to argue with. Unless arguing
is your only interest in posting, that is. We (Reg and I), each in
our own way, go rather the long way around the barn to say something
simple. I for one (and Reg by example, so I won't speak directly to
his motivation) are not here to simply litter facts across the board.
No you all have to suffer understanding too (as too many of you
already had the facts available before you asked any question).

So as an exercise, when you strip away style, what is left is:
But I do appreciate the love and respect you all have for it.

73's
Richard Clark, KB7QHC

Walter:

I think I might be able to guess why---when I first attempted to use
one--I tore it up and said some angry words (darn right nasty I
suspect)... I was a bit slow catching on with the smith chart, I am sure
you all were much more gifted and speedier... grin

Warmest regards,
John

"Walter Maxwell" wrote in message
...

"Reg Edwards" wrote in message
...

I can honestly say I've never used a Smith Chart in anger in the
whole
of my life.

Never had one in my possession for more than a minute just to inspect
it. Or by chance came across a condensed version in a book.

And I've worked on and with transmission lines from 0.1 Hz to 3000
MHz. At frequencies at which the Smith Chart is misleading and
useless.

I just didn't attend the same school as you lot.

It's habit forming like alcohol, tobacco and women. You can't think
straight without one in front of you. ;o)

But I do appreciate the love and respect you all have for it.
----
Reg.

Reg, you've aroused my curiosity on three points:

Why would you use 'Smith Chart' and 'anger' in the same sentence?

Why are there any frequencies where the Smith Chart is misleading and
useless? Which frequencies are they?

How can you say the Smith Chart is misleading and useless if you've
never used one, and never inspected one for more than a minute?

Walt, W2DU

In article ,
Tom Ring wrote:

I have 2 slide rules that I picked up recently, but I miss my easy on
the eyes yellow aluminum Pickett LogLogDeciTrig (I think that's what it
was) that got misplaced during a move a couple decades ago.

Keep your eye on eBay. Chances are good that you can pick up the
exact model you had before, either used-in-good-condition or
new-old-stock, for a reasonable price.

I'll admit that there's a danger to this, though. I started
collecting slide rules a few years ago, out of nostalgia, and got
bitten by the bug. I'm up to about 40 of them now... everything from
little 5" slipsticks, to an 8" circular, to an Otis King L cylindrical
in really fabulous condition. There are even a few (a Concise
circular, and a Pickett aluminum rule) with specialized X/L/C/F scales
for doing resonant-circuit calculations.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Dave Platt wrote:

In article ,
Tom Ring wrote:


I have 2 slide rules that I picked up recently, but I miss my easy on
the eyes yellow aluminum Pickett LogLogDeciTrig (I think that's what it
was) that got misplaced during a move a couple decades ago.


Keep your eye on eBay. Chances are good that you can pick up the
exact model you had before, either used-in-good-condition or
new-old-stock, for a reasonable price.

I'll admit that there's a danger to this, though. I started
collecting slide rules a few years ago, out of nostalgia, and got
bitten by the bug. I'm up to about 40 of them now... everything from
little 5" slipsticks, to an 8" circular, to an Otis King L cylindrical
in really fabulous condition. There are even a few (a Concise
circular, and a Pickett aluminum rule) with specialized X/L/C/F scales
for doing resonant-circuit calculations.


Oh, I know. I got bit by writing the response. I bought a K&E 1948
rule last night from ebay. 8.25 plus shipping. What a deal.

tom
K0TAR

On Wed, 01 Jun 2005 09:15:05 -0500, Cecil Moore
wrote:

I've added a Smith Chart graphic to my All-HF-Band-No-Tuner-Antenna
information on my web page.

This might very well be the best opportunity that I will ever have to
get in a plug for SmartSmith, which is not a demo but rather a full
featured SmithChart program with extensive Help file and is available
completely free at the following:

Download Site:
http://zaffora.f2o.org/W9DMK/W9dmk.html
High Speed Download Site:
http://64.217.230.66

Bob, W9DMK, Dahlgren, VA
Replace "nobody" with my callsign for e-mail
http://www.qsl.net/w9dmk
http://zaffora/f2o.org/W9DMK/W9dmk.html

Reg, you've aroused my curiosity on three points:

Why would you use 'Smith Chart' and 'anger' in the same sentence?

========================================
Just a figure of speech. "Anger" suggests setting about a job with
energy, determination and a sense of purpose. As distinct from mere
amusement.
========================================
Why are there any frequencies where the Smith Chart is misleading
and useless?
Which frequencies are they?
========================================
Depending on the size of the errors one is prepared to tolerate and on
the calculated parameter of interest -

Frequencies at which line attenuation per wavelength is not small.
Frequencies at which Zo is not purely real.
Frequencies at which CR is not equal to LG.
Frequencies at which the reflection coefficient is greater than 1.0

Comment : Zo is never purely real. CR is never equal to LG.
And the chart is good only to 2-digit accuracy anyway.

But Walt, you already know all this. Have you ever tried the Jones
Chart? ;o)
========================================

How can you say the Smith Chart is misleading and useless if you've
never used
one, and never inspected one for more than a minute?

Walt, W2DU

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

No problem! Worked it out for myself many years ago. Some years ago
I introduced to this newsgroup the excellent book "Transmission Lines"
by Robert A. Chipman, 1968. It aroused some interest. Some of you
obtained a copy.

It has a whole chapter devoted to the Smith Chart and fully describes
its limitations, imperfections, short-comings and approximations.

But the reason Chipman included the chapter was because of the great
savings in labour and time (in HIS day and age) when doing approximate
calculations on short, low loss, HF transmission lines such as antenna
feedlines for which it was designed. Which is all radio amateurs ever
use it for. Hardly any amateurs ever use it in anger. It has other
applications.

I first programmed a computer for work on transmission lines around
1960. At frequencies between 0.1 Hz and 1 MHz, frequencies at which
nobody would dream of using a Smith Chart. So I never became addicted
to it.
----
Reg.