Message-ID: <391C6885.A4BB64A8@bellatlantic.net>
Date: Fri, 12 May 2000 16:24:37 -0400
From: "Andre' Kesteloot" <akestelo@bellatlantic.net>
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To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: Optimal width for LF?
References: <09e401bfbc0e$5e55ab60$2301a8c0@maly.cz.gmc.net>
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Petr Maly wrote:

> Hello all
> I am just designing a new RX for 136 kHz band. It will have IF on 1 MHz with
> high quality x-tal filter with bandwidth 200 Hz. The main selectivity will
> by obtained on AF with passive filter with coils on pot cores. Till now I
> used similar filter with bandwidth about 50 Hz and it seems to be still too
> wide for LF. I was about to make it new with 15 Hz width. Somebody here
> mentioned 1 Hz wide filter which seems to me to be too narrow. At least, the
> filter cannot be narrower than obtainable osc stability. Can we make a
> little questionnaire here? What bandwidth do you use and what is the
> experience?
>
> 73, Petr, OK1FIG

My own experience is that your narrow-band filters, if physical filters  (i.e,
coils and capacitors, or crystals), are very liklely to ring. How about using
software filters?
73
Andre' N4ICK