Jon Ogden wrote:
>Carl, do you know what the "Scientific Method" is? The first stage is a
>word called HYPOTHESIS. Now I know that's a big word for some hams, but
>it really is a real word. A hypothesis is nothing more than an educated
>guess. Based on a hypothesis experiments are conducted. Based on those
>experiments, the hypothesis is proved right or wrong. If it is right it
>becomes a theory.
There is quite a lot of experimental evidence, so we ought to be well
beyond hypotheses and into the theory stage.
Parasitics that can be made to occur continuously have been well
understood for a very long time, and the cures are known.
What's still in doubt is the mechanism for events that suddenly occur in
an amp that may have been working normally for years. The simplistic
hypothesis -> experiment -> theory model doesn't work for intermittent
events like these. They can't be studied under controlled, reproducible
conditions; they can only be studied by working backwards from post-
mortem evidence. They also have a nasty habit of altering or
obliterating potentially useful evidence (for example, what was the
value of the suppressor resistor just before it was blown to bits? How
close were the grid and filament just before the event that left them
shorted?)
As yet there is no single theory about these events that explains ALL
the available evidence. None of the suggestions and opinions put forward
so far can do that. They either selectively ignore some of the evidence,
or else they aren't explained in detail and quantified.
73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.demon.co.uk/g3sek
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