[TowerTalk] Re: narrowband filters

[Jim Brown]

On Mon, 5 Jul 2004 19:21:46 -0000, Jim Jarvis wrote:

>I don't recall where this thread started, but I think it was someone
>looking for magic filters for in-band FD applications.
>
>None of this will help you IN band.  But I've been able to run ssb & cw at the
>same time, using 4 el 20's @ 70' spaced by about 400', with no difficulty 
whatever.

Where it started was me asking about narrower filters to suppress IN band 
interference (CW and SSB on Field Day). We are already working with 100 w 
to good dipoles at roughly 400' from each other, some at right angles and 
some parallel. And we are working with some radios that are "better" in terms 
of phase noise and intermod, and some that are worse. 

The discussion here has been good. I own several ICE bandpass filters, and 
am aware of comarable filters sold by Dunestar. All of these are bandpass 
filters, broadbanded  to cover an entire ham band. I'm looking for filters that are 
much narrower, more like 50-100 kHz wide. Specifically, I'm trying to learn two 
things. 

1) How much attenuation can I hope to get with practical filters over how 
narrow a bandwidth?

2)  Where can I find designs for practical filters, suitable filters for sale, or  
both? 

Jim K9YC