[RFI] IN-band Filters

Tom Rauch w8ji at contesting.com
Tue Nov 7 18:26:30 EST 2006

>  I'm looking for some form of filter for the purpose of 
> reducing interference between stations operating on the 
> same band (ie, fone-cw).  This would be used in a planned 
> multi-transmitter contest setup during Field Day 2007. 
> The bandwidth and slope would need to be good enough to 
> prevent fundamental overload of (and possibly damage to) 
> the receiving station.

You typically won't be able to have significant attenuation 
even with very good L/C components and stubs with their 
inherent low Q are out of the question.
I was somewhat successful using toroids with a Q unloaded of 
500 or so in a well designed filter, but tuning of the 
filter was critical.  Stubs actually have terrible Q, 
especially down on 80 or 40 meters.

The real key is antenna separation and good radios.

73 Tom 

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