[TowerTalk] coax stubs /bandpass filter

[jimlux]

Richard (Rick) Karlquist wrote:
> I've given up trying to make the lumped element argument to hams.
> Too hard to change belief systems.
> Coax stub filters are firmly entrenched ham radio folklore,
> regardless of whether they make engineering sense.


I think the engineering appeal (such as it is), is ease of fabrication. 
  Everyone has scraps of coax around, and the tuning is easy.. hook it 
up and grab a pair of garden shears and start cutting.  You could do it 
empirically (Keep cutting until the offending signal is "nulled") and in 
situ (e.g. field day).


> They are seldom if ever used for filtering in commercial HF radio systems.
> 
> BTW, the argument about the Q being "too high" goes away
> with the realization of the difference between loaded and unloaded
> Q. 
I figured that was the case, but thought maybe there's something else 
going on (interaction with the Tx or Rx Zs?)