[TenTec] Ten-Tec 411 Centaur Amp Problem

[geoffrey mendelson]

On May 31, 2010, at 10:55 PM, <wow_chf at hotmail.com> wrote:

> It is interesting how a simple fix for these problems doesn't seem  
> to be
> well known.
>
> I submitted the article draft to QST, and it was questioned by the  
> Technical
> Review folks, and although I have been published in QST before, they  
> could
> not see how this would "transform" the apparent input SWR.
>
> I have received hundreds of emails on how this technique worked for  
> radio
> amateurs all over the world.



I can't prove it mathematicaly, but I can give you a logical  
explanation. If you look at as a short wire, it probably has no effect  
in the circuit that you can model, or measure. If you look at it as  
part of the entire circuit including the finals of the radio and the  
input of the amp, it changes things. In effect it acts a delay line,  
which just shifts exactly where in the circuit things are.

Everyone can easily understand that a wave has it's voltage peaks at  
1/4 and 3/4's it length, and it's low points at begining and the  
middle. It's what happens in between that is less obvious and less  
understood.

So if you look at the entire circuit and see that at a particular  
frequency, the combination has a "bad" impedance, changing it would  
give you a "better" (or even "good") one. In the days of tunable  
finals on transmitters, or tunable input circuits in amps, then you  
could just slightly tweak one to change things.
Now the only way to change the effective impedance of the circuit is  
to add or subtract a little delay, moving where along the wave things  
are.

Geoff


-- 
geoffrey mendelson N3OWJ/4X1GM
Jerusalem Israel geoffreymendelson at gmail.com
New word I coined 12/13/09, "Sub-Wikipedia" adj, describing knowledge  
or understanding, as in he has a sub-wikipedia understanding of the  
situation. i.e possessing less facts or information than can be found  
in the Wikipedia.