[TowerTalk] TA-33 feed

[w8ji.tom]

> >The advertisements indicting feedline radiation as the cause of
> >TVI and BCI are a joke.  Does anyone really believe that feedline
> >radiation will cause TVI but radiation from the antenna does not?
> >
> >de  Tom  N4KG

The problem is often common mode currents on the TV antenna or CATV
feedline, not the Ham antenna.  
 
> I always figured that the radiation coming from a feedline was physically
> closer to the TV antenna than that coming from an antenna so it was much
> stronger and more likely to cause overload in the TV set.  I never saw it
> explained tht way, but it is the only explanation that makes any sense to
me!
 
Makes sense. 
 
> I have also heard that a high VSWR will render a low pass filter somewhat
> less effective and this could be the actual cause of TVI coming from a
> tranmitting system with a relatively high VSWR.  That makes some sense to
me
> as well.

That's not true. The only thing high SWR does is change filter response and
power ratings near the highest operating frequency. SWR at the operating
frequency, contrary to claims, has almost nothing to do with filter
performance at the TVI causing harmonic frequencies.

73 Tom

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