[CQ-Contest] Bandpass filter

Tom W8JI w8ji at w8ji.com
Sat Jul 7 16:19:22 PDT 2012

> Definitely
> not worth getting into the esoterics and trying to come up with
> something that will do it for less.  Just shoot the thing with the
> filter equivalent of a double-barreled shotgun and be done with it.

Hi Guy,

The reason why I find this interesting really centers around two things:

1.) making things work as well as possible for the investment appeals to me

2.) it's interesting to learn how stubs and filters actually work in systems

For example, my Force12 dual-band antenna actually suffers in gain and F/B 
ratio with wrong "unused feedline lengths" on the 10-meter section. By using 
a different length line length to my switch, the ten meter section is 
transparent to 15 meters.

It isn't that stubs and filters, if big enough, will not work. It's just 
that learning how they work is fun and useful, and helped me find an 
accidental problem.

Who knows. This might help someone build a better filter, fix a problem, or 
write a better filter or stub article.

73 Tom 

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