[Elecraft] Planning the next filters

[Dave Hachadorian]

I think you are optimally configured right now.  I used to have 
the 1.8 filters in my K3's, but sold them.  I think they hurt 
intelligibility more than they helped with QRM rejection. 
Remember that these are only roofing filters.  The DSP filter has 
a higher effective shape factor, especially on SSB.  Elecraft 
once said in an email that you could estimate the DSP shape 
factor by the formula (DSP BW SETTING+ 300 Hz)/(DSP BW SETTING). 
Especially for the SSB filters, the DSP shape factor is the 
determinant in bandwidth, as long as there is no signal just 
outside the DSP width that is causing the AGC to pump, or the A/D 
to overload.  Those effects, in the very rare event that they 
occur, can be minimized by judicious use of the RF Gain control.

As for the 250 Hz CW filter, If you look at the filter curves 
http://www.elecraft.com/K3/K3_filter_plots.htm  you will see that 
this filter should be really labeled KFL3A-370, and is not much 
different than your 400.

Dave Hachadorian, K6LL
Yuma, AZ




-----Original Message----- 
From: Chuck Chandler
Sent: Thursday, March 8, 2018 9:22 AM
To: elecraft at mailman.qth.net
Subject: [Elecraft] Planning the next filters

Right now I have the stock SSB and a 400 Hz filter in both main 
and sub
rcvrs.  I would like to add some a few at a time.  My first 
priority is to
add a couple to the main receiver, since it is the biggest chore 
to get
to.

I plan on a 250 Hz CW filter, but am going back and forth between 
the 2.1
and 1.8 kHz filters.  I know that narrowing the DSP to 1.8 gives 
a really
difficult to understand voice signal, while the 2.1 allows in 
more adjacent
signals.  However, the roofing filters may not behave in the same 
manner.
For example, the 1.8 could be set to turn on at 2.1 to take 
advantage of
skirt shape.

I primarily DX, and operate in some contests as well.  I know SSB 
contests
really need a narrow SSB filter.

Any suggestions on the matter from those who have gone this route 
before?

73 de Chuck, WS1L

-- 


===================
Chuck Chandler
chandlerusm at gmail.com
===================
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