Stuart,
I have read all of N6LF's material, some text
even before it was made public to others. OK?
My goal in all of this is along what Jim Brown
posted ... to encourage others to LEARN how all
this works and then make the best choices for YOU.
To NOT take statements that cannot be accurately
replicated at face value just because they read it
on an Internet forum.
Rather ask, "Is this in alignment with theory, and
then, will this really be better for MY setting?"
Look at the other posts, such as by WA3F where he
has invested his time to understand what is going on,
tried various ideas and then evaluated as he best can,
IF at the end of the day, was there an improvement or not?
Our common goal should be to present ideas in such
a fashion to encourage experimenting WITH accurate
understanding of why, or why not, their actual
results will be compared to others.
Times have changed, for you and I too, and we owe
those who will follow us to be accurate in our posts.
WW2 notes are fine as to history, but we don't live
in the environment now, probably never will again.
I would suggest that if we were to poll the audience
on this forum or on most others, the majority would:
A. Not own any of the simple equipment you cite.
B. And so have no idea how to use such.
At best, a SWR bridge and/or watt meter are owned by
many, then a less percentage might also own a "black
box" meaning one of the MFJ-259B, RF-1, etc. instruments.
No scopes, no RF current meters, and no way to build such,
and sadly in many cases no desire to understand why they
are useful. I believe we can help create that desire!
Thankfully, we can help change much of that by instead of
making questionable "ham lore" statements, we can on purpose
encourage others to LEARN how things really work, and then
decide if the changes could be an improvement for them.
The day when I could go visit one of my Elmers and ride away
with a couple of ARC5 chassis or old salvaged meters in the
basket of my bike for my next project, those days are gone.
Like it or not, we are the next generation's cyber-Elmers
and we need to consider that when we make our statements.
Where you and I am in total agreement is with the goal of
helping others to learn more and understand this topic, by
creating their own personal data resources from the various
sources, such as RSGB, ARRL, Orr's, along with web sources.
Many local university library's offer an option to checkout
their books to local residents. This can be a great resource.
One of the sharper NEW hams on here is James, K8JHR, who not
only has invested the time to learn, but also to experiment
and confirm that the suggestions of others, actually works
for him in his setting and not take blanket statements at
face value. And that sometimes they don't work for him too.
So how can "old xxxxx" like you and me help others to do
the same? I have no doubt that you and I probably either
own, or have access to everything you mentioned as to
that test equipment. That's great for you and me but ...
Without those simple tools you mentioned, how can anyone
know with a high level of confidence what their backyard
results will be? And that their efforts were not in vain?
That's why Rudi has stated over and over again to NOT expect
the same results as he did with his testing ...
... unless you can accurately measure the same data points.
Re-read what type of effort he said it required. Re-read how
he determined what had to be basically perfect.
And to NOT drift into the "ham lore", that elevated radials
are always ALWAYS going to be better. Maybe or maybe not!
Re-read your post below and note the specific critical details
you cited and ponder the following questions please:
"symmetric radials" ... what is the x.x dB loss here if I cannot
place ALL of my radials in such fashion?
"uniform layout in all directions, so local earth differences and
coupling are minimized" - same question, what is the x.x dB loss
here if my local earth is not uniform in all directions?
"I see nothing exotic needed in instruments if symmetry and
good practices in vertical antenna construction are followed" -
again what is the x.x dB loss here if such is not followed exactly?
Well? If you and I cannot answer the above questions with hard
numbers, then why should we make a posting saying that elevated
radials are better? What if Joe Ham has only a basic SWR bridge
of unknown accuracy? Then what?
I quote your posting, "They are the most efficient."
Rudi did NOT make any such statement, instead he is very
open as to what is REQUIRED to replicate his results.
Will Joe Ham's switching to elevated radials REALLY
be an improvement over the 9 ground mounted radials
that he has run as long as he can, where he can? Is
he going to be able to notice any difference to make
the work and expense worth it for him in HIS yard?
The correct answer here is ... we simply do not know!
But Joe Ham reads on the Internet that such and such is true.
This is the challenge I have with "ham lore" that is too
often presented and then accepted as the truth, when in
reality that statement is not always true.
I'll repeat what I said earlier ...
My goal in all of this is along what Jim Brown posted
... to encourage others to LEARN how all this works
and then make the best choices for YOU.
To NOT take statements that can not be accurately
replicated at face value just because they read it on
an Internet forum and believe/hope such is true.
Rather ask, "Is this in alignment with theory, and then,
will this really be better for MY setting?"
I really DO want others to TRY ideas and see IF they work
for their settings. It may not, due to either limitations
on what they have to evaluate it, due to lack of any special
tools to measure things, or specific differences in their
local setup, like unique land profiles. Understand why!
Rick and I have been discussing this off-line and again
we share a common goal of helping Joe Ham to understand
how all this works, and then what works best for them,
in their setting and within their actual resources.
I don't believe these forum posts are a waste of time, as
long as everyone understand the above stated goals.
Perfection is NOT the target here, doing the best you can
with what you have, such is excellence and a worthy goal.
Let's re-visit Rick's revised statement WITH the details
that may influence your or my real world observations:
First, let's rewrite the statement for consideration:
"Various verticals used here over a period of time
have appeared to be 12-18 dB stronger than a dipole
in certain repeatable settings"
>From reading the recent posts, someone on here may now
have either a new understanding or a more accurate view
of the following:
1. Path wave angle matters, "high angle" or "low angle"
2. Antenna orientation matters, "off the ends"
3. Propagation matters, Grayline, solar flare, time of year
4. Relative linear value of dB to each S-meter unit
5. All of the above matters together in multiple ways
6. You fill in the blank here with terrain, power lines, etc.
Now that Rick has provided more details, what he did
there, and how he measured the relative changes, Joe
Ham can look at this in a more accurate light now!
He or she can now understand why such a statement for
a given set of variables, could be very accurate.
As each of the statement's details can be LEARNED or
understood as to why they matter, and then properly
APPLIED to each of his/her individual settings. QSL?
I believe that's what you want too, but first you and I
need to LEARN and APPLY that the newer hams today do not
have the same resources (normally) on-hand that we might
have and that we may have used for many years now.
How can we encourage them to understand and perhaps consider
buying/building some of these same tools? What is better?
A. Make blanket statements that are way too 'fuzzy' which
tend to over promise and instead deliver disappointment.
or
B. Provide resources to learn, and then apply, by explaining
why they need to think for themselves and confirm it?
Rudi did everyone a great service with sharing his results, but
for whatever reasons, some decided to draw other conclusions
and then create "ham lore" which is tough to overcome, unless
one learns the principles and then applies it to their setting.
Learn to understand personally.
Apply to use practically.
And most important ...
Enjoy this hobby!
73 de Billy, AA4NU ... who still has much to learn too.
-----Original Message-----
>From: Stuart Rohre
>Sent: May 21, 2012 3:37 PM
>To: Discussion of Ten-Tec Equipment
>Subject: Re: [TenTec] Radial Research
>
>Billy,
>If you view Rudy's excellent power point and look at the pictures, you
>find that Rudy uses symmetric radials as is usually done with verticals
>when there is adequate room. His site has a uniform layout in all
>directions, so local earth differences and coupling are minimized. His
>measurement tools are often home made or basic, ie the radial current
>transformer is simple to replicate with circuit board soldered together,
>hobby copper tubing (or brass), and a core suited for the band being
>tested. A relative voltage is developed which represents current in the
>radial being measured.
>HP RF millivoltmeters are commonly available to hams from surplus
>sources at reasonable prices. These are good for reading the voltages
>developed from transforming radial current.
>
>I see nothing exotic needed in instruments if symmetry and good
>practices in vertical antenna construction are followed. 20 MHz
>oscilloscopes are common and reasonably priced, and would also also
>suffice for voltage measurements for the lower bands.
>
>Back before WW2, hams were measuring radial and feed line currents with
>thermocouple RF current meters and they are adequate for work at 40m and
>below today as well, and likely most are marked as good up to 20 MHz,
>thus good for at least 20m and as relative indicators somewhat beyond.
>They can be used in opposite pairs of radials to preserve symmetry and
>detect any relative radial current variation other than that of the
>measurement device. Most would require use of a transmitter as your
>signal generator, but some exist that have a 0 to 1 Amp RF scale.
>
>The modeling studies of L.B. Cebik, W4RNL, show that differences in
>which place you feed an antenna can alter the pattern slightly. (Such
>as on a symmetric Horizontal Loop).
>
>If your local soil varies so much that your radial currents are not
>balanced, the effect will likewise alter your pattern, but that does not
>prevent the vertical from working as expected, it just may favor one
>direction over another, slightly.
>
>The variations in the propagation has a much greater effect on the
>signal and for that we have no control, once the signal leaves the
>antenna. Most of the signal influence once radiated depends on the
>earth out beyond the Fresnel Zone, some 5 wavelengths beyond the antenna
>location and usually out of the ham's control as to what is on the earth
>at that distance---buildings, ponds, different terrain or elevation.
>
>Extensive radial systems are needed at AM band because their main
>interest is a nice controlled ground wave pattern to cover their
>intended broadcast area, and nulls in the directions of any co channel
>station to which they might cause interference.
>
>Hams on the other hand have different concerns in their main use of sky
>wave signals.
>
>-Stuart
>K5KVH
>_______________________________________________
>TenTec mailing list
>TenTec@contesting.com
>http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|