[Boatanchors] Cheap & Easy Selectivity

[rbethman]

Alex,

I agree that all are capacitors.

I was using different things as examples of a way to get around a 
manufactured one.

I may have stretched it too far, but was trying to also make the point 
that the definition of "gimmick" can be found readily, and never bring 
electronics into it.

My view of the "gimmick" has usually insulated wire attached at ONE end 
to two different places in a circuit, twisted or wrapped around each 
other, with the length trimmed to optimized the desired circuit 
characteristics.

I haven't run across zip cord being used.  It would seem to be longer 
for the same effect, but the difference in the dielectric of the 
insulators would have to be run through to see what the real difference is.

Bob - N0DGN

Alex Whitaker wrote:
> "...it is possible to capacitively couple the antenna directly to the
> next RF amplifier grid, or to the mixer input grid, by wrapping an
> insulated wire around any exposed wiring in the grid circuit.  This
> forms a gimmick, which has a few picofarads of capacitance to the wire
> around which it is connected."  Electronic Communication - 3rd Edition -
> Robert L. Schrader.  
>
> I personally have only heard the term gimmick in reference to one wire
> twisted around another in the manner described above.  I believe Bob
> Bethman's examples of glass between two copper plates, or a long screw
> used as he states describe capacitors, but not a gimmick.  
>
>
> 73,
>
> Alex 
> AA9XY
>   
<BIG SNIP>