Wow. I attend to important things for a couple days and look what happens.
I think some of you may have missed "intended to be humorous" in my
initial post.
Dave here is putting words in my mouth. I have plenty of understanding
and have a mass of excellent data on which to draw. I just approach
things differently than some other people reading this, and I arrive at
conclusions I find satisfactory. That is really all that matters to
me. I may also have different design goals.
Good day,
Mark N5OT
On 9/10/2019 6:11 PM, David Gilbert wrote:
Not to beat a dead horse, but no ... you aren't saying the same thing.
N5OT said to just build it and see if it works "good enough", without
further understanding or even without anything to compare it against.
Conversely, you said you relied on the K6STI's model to "do your
homework ahead of time" and that you trusted the model over someone
else's experience whether or not it was good enough.
Those are opposite approaches whether you recognize it or not, and for
the record I would have done what you did as opposed to N5OT's
approach. I'm a firm believer that as practitioners of a technical
hobby we should make an effort to understand the science of what we're
doing BEFORE we make the tradeoff decisions of cost, time, effort,
hassle, need, probability of success, etc.
Dave AB7E
On 9/10/2019 3:24 PM, Bob Shohet, KQ2M wrote:
Actually we are saying the same thing.
1) Build it and put it up!
2) Take it down or adjust it and put it back up again.
3) Repeat as needed.
4) Get on and make lots of q’s and have fun
In each case you clearly have a specific design in mind – a model or
plan whether computer generated, hand drawn or something else, with
measurements that we use to build what we put up. We don’t just
invent it in our head with random materials and random measurements
and slap it together.
In addition, while modeling programs are based on math and theory,
they are far from absolute; especially when dealing with terrain
where the measurements are not absolute either. And all computer
programs have points of inflection where the results change greatly
based on the tiniest of dimension changes and those dramatic result
changes are artifacts of software program limitations. Anyone who
does a lot of computer modeling knows that. Theory is not the same
thing as reality. Modeling programs are “guestimates” at best.
The rest of your comments are not worthy of a response.
Bob KQ2M
From: David Gilbert
Sent: Tuesday, September 10, 2019 6:01 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] "experts" on loading towers on low bands
You and N5OT aren't saying the same thing at all. He said to just
experiment and see what works well enough to be acceptable, while you
said you ignored the practical experience of other hams (stuff that
"works" or doesn't) and instead used a modeling program (which is based
purely on math and theory) to make your decision.
It's odd to see two guys pat each other on the back for reinforcement
when they don't even understand they have opposite stances. Whatever
happened to logical thinking?
Dave AB7E
On 9/10/2019 1:44 PM, Bob Shohet, KQ2M wrote:
Mark has nailed it!
One of the nice things about making something and seeing it it works
well enough is that what you make doesn’t know how well it is
supposed to work and doesn’t care. :-)
So if it works it works regardless of what anyone thought beforehand.
Usually if it works (and no one thought it would), we find out long
after the fact why it worked, and generally it was something that
wasn’t known or understood at the time, and now the field advances
with the “Gee, I wonder why it works so well?” study and discoveries
afterwards.
Simple example... I wanted to put up a 4-stack on 15 meters when I
built my station. I new that I needed heights of 30’, 60’ and 90’,
but with 100’ of tower it didn’t seem to make sense to put another
15 above that. The thinking was that even on a tall mast, the 90’
and another 15 at 109’ would be too close and would phase poorly
especially if they were pointed in different directions. Everyone
that I asked about this said so. These guys built great stations
and are great ops. You know all of their calls. But I modeled the
stack with K6STI’s YO and it looked GOOD! I asked them again. “NO!
I would not do it” came the answer in unison. Thankfully I did my
homework beforehand and I chose not to listen to the advice of
people that I respect.
So I built it and put it up anyway. The 5L at 109’ was and is a
KILLER!, especially when in phase with the 90’. I believed the
modeling over my terrain. The software was correct and my 15 meter
experience has been awesome for the past 20 years. (And I have
thanked Brian, K6STI many times over the years)
Before I put it up I reasoned that if it didn’t work I could always
take it down. But if it did work, I would never want to! :-)
Very high reward to risk ratio!
Moral of the story: Model it, build it well, put it up and see how
it does!
73
Bob KQ2M
From: Mark - N5OT
Sent: Tuesday, September 10, 2019 4:11 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] "experts" on loading towers on low bands
I'm a big fan of "experiment trumps theory" and basically I have spent
nearly 50 years doing the following:
1. Make something.
2. See if it works well enough.
3. If it works well enough, you're done. If it doesn't, change
something and see what happens.
Clearly I'm just an amateur. But because I'm on TowerTalk™ I can say I
make "educated guesses."
Love you guys,
73 - Mark N5OT
(intended to be humorous - everyone carries a bucket of gasoline in one
hand and a bucket of water in the other - they get to choose which one
they throw on the fire - I choose water) (most of the time)
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