[CW] 600 Hz Resonant Speaker for CW - Plans

[wealsowalk at aol.com]

Ken, modern receivers with "narrow filters" on the IF?usually means 300 or 250 hz wide.? A mechanical device like the one you are talking about here is very much sharper than that and can be a very large help.? You can also?use an electronic audio filter to get down to 1 or 2 hz wide band now, but it is not usual to see those and the ringing sometimes gets on your nerves a bit.? Either way can be very helpful though.? Another way to get at a signal is to feed the audio to a computer audio card and scan it, like what is done for psk31, and then you are really spreading out the noise you would ordinarily hear so that you can ignore that part.? Also you can make multiple scans and average out the noise so that signal detection by computer far outperforms either the narrow filters or the mechanical method.? Still, the mechanical resonant speaker is very intriguing, though expensive by comparison with electronic audio filters.

Bill

AC6QV


-----Original Message-----
From: LA5HE Ragnar Otterstad <la5he at otterstad.dk>
To: CW Reflector <cw at mailman.qth.net>
Sent: Mon, Aug 31, 2009 8:55 am
Subject: Re: [CW] 600 Hz Resonant Speaker for CW - Plans





I think your spelling "resonant" is more correct than "resonate" as used 
in the article. I am curious to know how it can be of much help, unless 
the receiver you are using does not already have any narrow filters, or 
has a lot of noise in it's audio stages? I almost always use headphones 
for CW listening anyway.

Ken N6KB


Works like a very selective audio PEAKFILTER.

73  Rag   LA5HE


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