Content-Transfer-Encoding: 8bit
Date: Fri, 26 May 2000 10:24:50 -0700 (PDT)
From: "Clifford Buttschardt" <cbuttsch@slonet.org>
To: rsgb_lf_group@blacksheep.org
Cc: "John Davis" <longwave@mindspring.com>
Subject: Re: LF: Optimal width for LF?
In-reply-to: <392056A6.F57284D1@slonet.org>
Message-ID: <Pine.GSO.3.95.1000526101615.22754M-100000@oso.slonet.org>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org
Sender: <majordom@post.thorcom.com>

Further update on the filters mentioned below.  I am convinced that any
filter has enough tolerance variations that experimental "tweeking" is
necessary for minimum ringing.  Most of us are using 800 hertz center
frequencies obtained from a crystal source.  This signal was then gated
by a function generator (a morse keyer works just fine too!) while
carefully adjusting all poles.  Sometimes interchanging pole position is
valuable!  The conclusion is that experimentation is more valuable than
calculation for these filters!   Cliff K7RR


On Mon, 15 May 2000, Cliff Buttschardt wrote:

> Christer and the group.  I was delighted to get the two URL's
> containing the 30 Hz filter and noise blanker.  You might
> remember
> some years ago the "HDO" phase linear filter.  That was when I
> was W6HDO rather than K7RR.  For years that filter served us
> well.  I really enjoyed the experimental way of finding least
> ringing, so I placed variable resistors in the old design
> using
> an automatic key.  Even the old Williams textbook approach
> benefited from experimental "tweaking".  73  Cliff  K7RR  
> 
> C Andersson wrote:
> > 
> > >Could you post a brief text summary of your design?
> > >73, Bob ZL2CA
> > 
> > PA0LQ filter descriptions:
> > http://www.alg.demon.co.uk/radio/136/af_filter.htm
> > http://home5.swipnet.se/~w-54761/pa0lq_filter.htm
> > 
> > 73
> > Christer, sm6pxj
> 
>