I use a 100 uF capacitor across my speaker to eliminate the hiss.
It is simple and does a good job.
Carl Moreschi N4PY
cjm@qvssoftware.com
----------
> From: Dr. Gerald N. Johnson, P.E. <geraldj@ames.net>
> To: Simmons, Reid W <reid.w.simmons@intel.com>
> Cc: 'weingaertner@nac.net'; K & H Darwin <darwin@together.net>; TenTec
List <tentec@contesting.com>
> Subject: Re: [TenTec] Omni C / Corsair Hssssss.
To: <tentec@contesting.com>
> Date: Thursday, February 03, 2000 3:12 PM
>
>
> I use a metal cased Motorola mobile speaker from the Motrac days. It
> doesn't pass much high pitched hiss. And I round off more with the Pass
> band tuning.
>
> There have been some passive low pass filters suited to speaker lines
> published in QST and recent ARRL handbooks.
>
> I've built a couple of my own designs that are switchable for cut off
> frequency, they are 4 ohms in and out and have at least 4 different
> cutoff frequencies in essentially a 2:1 step from about 450 Hz going up.
> They clean up hiss and sidetone distortion on most any radio. A CW
> signal coming through a narrow filter then with the pitch tuned to about
> 400 Hz with that step switched in on the speaker, there's nothing there
> but CW, very little noise. My reproducible design has been printed in a
> local club newsletter so I probably could scan something from it and
> send it out. It needs a bunch of switch poles, a bunch of capacitors,
> three large RF chokes (available from digi-key) and a couple audio
> transformers that are available from Hosfelt or Radio Shack. A 7th order
> Chebychev low pass takes away a lot of unwanted filter leak around and
> IF and audio circuit noise.
>
> 73, Jerry, K0CQ
>
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