[TowerTalk] Fw: Feeding single band HF yagis 500+ ft from the shack

[Ignacy Misztal]

1 db and even 2 db is hard to discern. But it would clearly have an effect
when quantified as success in thousands of attempted QSOs, e.g., in
contesting. So we can look at the issue in statistical terms as a % of
success with an extra 1 db.

In contesting, the  number of QSOs is a function of many variables
including the operator skill, station quality, location, length of
participation and signal strength, Adjusting for the same conditions except
the signal strength, we can find approximately the number of QSOs for any
signal strength. For example, 1extra  db for a station with an
average operator, 100W and a tribander  in CQ WW CW could be 23 QSOs.
Simple extrapolation would then suggest 11 extra QSOs for 0.5 db and extra
46 QSOs for 2 db. So we can quantify not only an effect of 1 db but even a
fraction of a db.

Ignacy NO9E

On Wed, May 18, 2022 at 12:39 PM <john at kk9a.com> wrote:

> I do not know of any such study but I agree with K9YC that every bit
> matters.  Certainly at some point having an extra 1dB of gain or 1dB less
> loss becomes very expensive so everyone has to weigh how important it is to
> them.  I'm sure that K3LR minimizes every fraction of a decibel of loss at
> his station.
>
> John KK9A - W4AAA
>
>
> Kim Elmore N5OP
>
> I don't mistrust contesters that tell me they're certain of this, but...
> I'm wondering how they *know* that the difference is 1-2 dB on the
> *receiving* end? If they can increase the smoke by 1-2 dB and all of a
> sudden make the QSO, how do they *know* that's what did it? HF
> propagation is funny stuff. I do a LOT of statistics in my job as a
> research meteorologist/scientist, even though I'm not a formally trained
> statistician, and this is always my first question when presented with
> statements like this. Show me the data and how it was analyzed.
>
> I'm pretty sure that there is no such data set in existence and I don't
> know of a good way to collect one. However, I suspect that the innate
> variability of ionospherically propagated HF signal strength is far
> larger than 1-2 dB and that any p-values we'd find at the 1-2 dB
> thresholds would be pretty large and so deemed statistically
> insignificant. I suspect there are too many degrees of freedom to ever
> pin this down.
>
> I have no intention of starting a fight or creating discord. I *deeply*
> respect Jim's judgement and experience. Even so, I'd love to craft an
> experiment that would allow us to statistically determine the dB
> threshold that truly makes a difference on each band. While I'm
> spitballing, I might as well include different geomagnetic conditions as
> well.
>
> That said, there's also a good argument for not wasting a dB if you can
> affordably avoid it.
>
> 73,
>
> Kim N5OP.
>
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