Since several expressed interest, I looked thru my
files last night and came up with the following
articles for building a speech bandpass filter. The
first is by Ed Wetherold, W3NQN. His article "Passive
Audio Filter for SSB" is in the Technical
Corrospondence section of the Dec. 1979 QST, page 50.
The other appropriate article is by Bob Myers, now
W1XT. This article "The Crud-O-Ject" can be found in
the Feb. 1972 QST, page 11. I have built both of these
and they do a great job of eliminating the hum and
hiss. I still use them on a daily basis. Most of the
active filters will also do the job also. I have a
real fancy CW & SSB active audio filter that I built
years ago. It also eliminates the hum/hiss crud but
the audio filters just seem a lot simpler. I just
install them in the audio line and forget about them.
As far as I know these articles are not available
online. I can supply paper copies if anyone needs them
if you send me an SASE.
K3ND
G. Steward
282 Perkasie Ave.
Quakertown, PA 18941
73, Stew...
> > Subject: Re: Topband: eliminating radio hum/hiss
>
>
> > I have used an external, passive audio filter
> (from a
> > W3NQN QST article) for years on various radios and
> now
> > on my 850. It uses a bandpass audio filter to roll
> off
> > low frequencies below 300hz (eliminates hum) and
> above
> > 2500hz (eliminates hiss). I've used them for years
> and
> > wouldn't be without them. I have 3-4 of them, one
> on
> > each of the different radios. I can post the
> magazine
> > issues that contain the information if there is
> any
> > interest (I can go through my files tonight).
> >
> > 73, Stew K3ND
>
>
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