Richard Clark wrote in
:

I am wondering why you are trying to resurrect this train wreck.

I was seeking comment on the issue of asymetric branch feed topology.

It was put to me that accounting for the phase shift due to the different
branch lengths does not fully account for the time lag. My contention is
that in transforming the problem to the frequency domain, conversion of
time lag to phase lag fully and properly accounts for the different
branch lengths.

Gordon's paper was offered as evidence that my feed was "WRONG!".

Yesterday, I note that Kraus has a clear diagram of branch vs distributed
feed, and the technique of transposition to offset a half wave phase
delay.

I also note the ARRL agrees with me (http://www.vk1od.net/lost/Fig7.png
(c)), but that isn't a bullet proof recommendation!

I am now confident my critic was wrong.

Owen

On Mon, 15 Dec 2008 21:50:04 GMT, Owen Duffy wrote:

Richard Clark wrote in
:

I am wondering why you are trying to resurrect this train wreck.

I was seeking comment on the issue of asymetric branch feed topology.

Hi Owen,

That seemed to be a strain based on the illustration offered as it
wanders the field.

It was put to me that accounting for the phase shift due to the different
branch lengths does not fully account for the time lag. My contention is
that in transforming the problem to the frequency domain, conversion of
time lag to phase lag fully and properly accounts for the different
branch lengths.

Too many conversions going on there in your statement. I don't see
any transformation (conversion?) to OR from the frequency domain; and
I don't see what that would offer. Distance, "polarity," phase and
time are all hands on the same watch. Their conversion is trivial -
as you appear to be rebutting to your critic.

Gordon's paper was offered as evidence that my feed was "WRONG!".

The offeror left it you to sort it out rather than arguing their own
case, hmm?

Yesterday, I note that Kraus has a clear diagram of branch vs distributed
feed, and the technique of transposition to offset a half wave phase
delay.

I also note the ARRL agrees with me (http://www.vk1od.net/lost/Fig7.png
(c)), but that isn't a bullet proof recommendation!

True.

I am now confident my critic was wrong.

If the criticism is, as you offer above about accounting for "time
lag," as if that fell into some special category, then your confidence
is well grounded.

When I examine your other correspondence to piece together the story,
then both sides of the argument have valid points. Yours, being more
general, is more conclusive.

The second take-home here seems to be, if you wish to teach someone
how to perform a task, or build a project, you shouldn't do it with
negative examples without being encyclopedic to completion (which
invites boredom).

A proof with the free version of EZNEC was easily achieved with some
minor elaborations for the NBS Yagi. That is the beauty of modeling,
it encompasses ALL the ways to fail or succeed.

73's
Richard Clark, KB7QHC

"Richard Clark" wrote in message
...
On Mon, 15 Dec 2008 21:50:04 GMT, Owen Duffy wrote:

Richard Clark wrote in
m:

I am wondering why you are trying to resurrect this train wreck.

I was seeking comment on the issue of asymetric branch feed topology.

Hi Owen,

That seemed to be a strain based on the illustration offered as it
wanders the field.

It was put to me that accounting for the phase shift due to the different
branch lengths does not fully account for the time lag. My contention is
that in transforming the problem to the frequency domain, conversion of
time lag to phase lag fully and properly accounts for the different
branch lengths.

Too many conversions going on there in your statement. I don't see
any transformation (conversion?) to OR from the frequency domain; and
I don't see what that would offer. Distance, "polarity," phase and
time are all hands on the same watch. Their conversion is trivial -
as you appear to be rebutting to your critic.

Gordon's paper was offered as evidence that my feed was "WRONG!".

The offeror left it you to sort it out rather than arguing their own
case, hmm?

Yesterday, I note that Kraus has a clear diagram of branch vs distributed
feed, and the technique of transposition to offset a half wave phase
delay.

I also note the ARRL agrees with me (http://www.vk1od.net/lost/Fig7.png
(c)), but that isn't a bullet proof recommendation!

True.

I am now confident my critic was wrong.

If the criticism is, as you offer above about accounting for "time
lag," as if that fell into some special category, then your confidence
is well grounded.

When I examine your other correspondence to piece together the story,
then both sides of the argument have valid points. Yours, being more
general, is more conclusive.

The second take-home here seems to be, if you wish to teach someone
how to perform a task, or build a project, you shouldn't do it with
negative examples without being encyclopedic to completion (which
invites boredom).

A proof with the free version of EZNEC was easily achieved with some
minor elaborations for the NBS Yagi. That is the beauty of modeling,
it encompasses ALL the ways to fail or succeed.

73's
Richard Clark, KB7QHC

Hi Richard

What is the reasoning used to indicate 300 ohm line is used in (B) of the
referenced http://www.vk1od.net/lost/Fig7.png .?

Jerry

On Mon, 15 Dec 2008 23:57:39 GMT, "Jerry"
wrote:

Hi Richard

What is the reasoning used to indicate 300 ohm line is used in (B) of the
referenced http://www.vk1od.net/lost/Fig7.png .?

Hi Jerry,

It should follow the rule of being the square root of the product of
the source and load Z.

73's
Richard Clark, KB7QHC

"Jerry" wrote in
:

....
What is the reasoning used to indicate 300 ohm line is used in (B)
of the
referenced http://www.vk1od.net/lost/Fig7.png .?

The figure is is from the ARRL Antenna Handbook.

In (b), the numbers are rounded. A nominal 280 ohm dipole via 1/4 wave of
400 ohm line gives 570 ohms at the tee. Two such branches are paralleled
for 285 ohms, which on 300 ohm main feed line line results in a VSWR of
1.05... should be acceptable.

Does that help?

Owen

Richard Clark wrote in
:

....
The second take-home here seems to be, if you wish to teach someone
how to perform a task, or build a project, you shouldn't do it with
negative examples without being encyclopedic to completion (which
invites boredom).

Richard,

That same thought occurred to me on first reading it. Teaching what not
to do has its place, but it 'dumbs down' the learner.

Explaining the concepts, and how to use them imparts empowering knowledge
more than rote learning of negative Rules of Thumb.

Still, people keep telling me that that is all old world thinking, today
you train (instead of educate) people to specific and narrow tasks, and
competency for immediate tasks (train to the need) is more important than
knowledge of principles and concepts.

I have quals to opearate a fork lift. One of the questions I was asked
for assessment was "name six places that you should not park a fork
lift". Of course, one cannot just nominate any 6 places that would be
inappropriate, it MUST be THE six places on the assessor's list. One of
them is "on a railway track". So, rather than training people to identify
hazards, and not park the fork lift in a hazardous place or way,
"competent people" know the rule to not park the fork lift on a railway
track. No doubt accident / incident driven training... a negative driver.
(I will leave you to think about 5 other stupid places to park a fork
lift!)

Owen