[CQ-Contest] Re: Choice of CW Narrow filters

n6tr at teleport.com n6tr at teleport.com
Fri Apr 16 10:42:07 EDT 1999

> However, when using the narrow filter adjacent to some strong stations, I am
> frequently asked to QSY by one of them, even though he isn't bothering me. 
> The only reason I'm there, of course,  is that I couldn't find a clear spot
> wide enough for the 500 Hz filter.  So, am I obligated to move, or not?

Nope.  It's a jungle out there - if you are getting results and are 
happy with the situation, then you don't have to do anything.  

With respect to 500 versus 250, I think the shape of the filter is
much more important than 6 db points.  Typically, you need to get
around 30 db before you can consider someone outside of your 
passband.  A really good 500 Hz filter could easily have more
rejection of someone 400 Hertz away from you than a poor 250 Hertz
filter would.

Yes - 400 Hertz - because your passband goes 250 Hertz up and down
from your center frequency.  

I have used some of the "super" filters sold as after-market improvements
for the common radios.  These tend to have very sharp skirts and are
really nice filters.  However, I can't use them if they are too narrow.
Typically 500 Hertz is the max.  Otherwise, I feel like I am not connected
to all of the radio frequency spectrum I need to be in order to run 
stations efficiently.

For my own personal perferences, I really have adapted well to the 
stock 500 Hz filters in the TS850.  Having the two filters is series
almost makes them perform like a really good after market 500 Hz filter.
For most QRM situations, either switching to the other sideband, or 
cranking on the passband tuning a little solves the problem  This is
what I have used in the past seven ARRL SS CW contests.

The only thing for sure is that everyone develops their own preferences
for what they like to use and there isn't one best way.  However, I
do agree with the comment that wider is better and using the organic
DSP between your ears to it fullest ability will enhance your score.

I recently discovered the power of this DSP when doing moonbounce
work on six meters.  I have always thought that you had to use really
narrow filters on your receiver to hear weak EME signals.  However,
what I found was that it was EASIER to copy weak EME signals using
the SSB bandwidth positions!  I polled other weak signal guys, and 
many of them do the same thing.  It seems that giving the brain a
full spectrum of sound to reference against allows it to pick out
the weak signals better.  This may not work for everyone as there are 
still those who prefer narrow bandwidths, but it was a surprising

73 Tree N6TR
tree at contesting.com

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