[Elecraft] adding 250Hz filer, any improvement?

[Edward R. Cole]

Vic and all who replied,

I kind of cheated when I made my inquiry.  I omitted the fact that I 
was actually asking about copying eme CW (though some of you may have 
guessed).  I am the only station in Alaska that regularly operates 
2m-eme.  Since Alaska counts both for WAS and DXCC that makes me in demand.

I have not operated CW eme for a long time, but am about to start up 
again (I have mainly operated digital eme since 2003).  One of the 
main reasons for my K3 purchase was operating CW eme.  (I also use it 
on 500-KHz)

In the past I was using my FT-847 which only has the 2.2-KHz SSB 
filter.  I used the DSP CW filter on 400-Hz for searching for signals 
and then narrowed down to either 200 or 100-Hz (the FT-847 DSP is not 
variable and provides only 400/200/100/25 Hz filtering).  My hearing 
is bad and I wear hearing aids full-time, so I can not dig out weak 
signals as well as some.  Narrowing bandpass is essential.

I have not tried to copy CW eme with the K3, yet.  I am waiting for 
my new DEMI 144/28 transverter.  But I did experiment listening to 
weak CW on 20m and tried out the APF feature.  It works super!  I am 
looking forward to trying it out on eme.

This coming weekend is the annual 432 & 1296 SSB eme event (not 
really a contest), so I am trying to get set up for that.  There will 
be both CW and SSB signals to listen to.  Unfortunately, I found that 
one of my FET's is bad in my 1296 amplifier so I will not be 
transmitting.  But it should be fun listening into all the 
stations.  I have a 1296/28 transverter to use with the K3.

73, Ed - KL7UW

------------------------------

Message: 11
Date: Wed, 09 Feb 2011 08:13:19 -0800
From: Vic K2VCO <vic at rakefet.com>
Subject: Re: [Elecraft] adding 250Hz filer, any improvement?
To: elecraft at mailman.qth.net
Message-ID: <4D52BD1F.8030308 at rakefet.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

I see that others have told you that you can narrow the DSP and it 
will be just as good as
long as there are no nearby signals greater than about S9+20.

Let me add that a huge improvement in copyability of weak CW can be 
gained by using the
APF in current firmware. It has a bandwidth (I believe) of about 30 
Hz at 6 dB points, and
also provides a slight gain boost. It's easiest to select 1 Hz tuning 
steps (tab 'fine')
when tuning with it on.

I usually use a DSP bandwidth of 300-400 Hz and APF on when copying 
really, really weak
signals.

I know there are guys like W4ZV who have a DSP between their ears 
that does a better job
with wider bandwidths, but not all of us have this ability!




73, Ed - KL7UW, WD2XSH/45
======================================
BP40IQ   500 KHz - 10-GHz   www.kl7uw.com
EME: 144-1.4kw*, 432-100w*, 1296-testing*, 3400-winter?
DUBUS Magazine USA Rep dubususa at hotmail.com
======================================
*temp not in service