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RE: Re: AO40Rcv and soundboards? ditto

At 02:52 08/11/2001 +0000, you wrote:
>  I second that motion. I'm also in commercial broadcasting, and have hade
>the same experiences. You hit it right on the head. I just grabbed an old
>Radio Shack 10k-100k transformer and slapped in between the receiver and the
>audio input to the soundcard. All hum gone!
>Gunther Meisse
>-----Original Message-----
>From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org]On
>Behalf Of Jim.Walls@sce.com
>Sent: Wednesday, November 07, 2001 10:42 PM
>To: amsat-bb@AMSAT.Org
>Subject: Re: [amsat-bb] Re: AO40Rcv and soundboards?
>Moe - AE4JY said (in part):
> > 4. 60/120Hz AC hum pickup can be a problem.  It may not show up on the
>waterfall display since the display doesn't go that low but would screw up
>the decoder.
>I will second this one.  I have a background that includes working as a
>broadcast engineer wherein my responsibility was a studio for a major radio
>traffic reporting service.  The biggest source of hum and noise problems I
>had to deal with was unbalanced audio lines.  Either a balanced device

And again, from a broadcasting background, every audio and control line is 
600hm balanced, shielded twisted pair. Suitable transformers can be had 
almost anywhere, preferably centre-tapped to allow for a dc 
"phantom-circuit" and ensure ac balance. Keeps RF out too!!!!


Norm, VK2XCI
Voice of The Edge of The Outback

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