RE: [amsat-bb] Re: AO40Rcv and soundboards? Isolation xformer.

["Gunther Meisse" <gjmouse@xxxxxxxxxx>]

I just use a little junk matching transformer from RS: # 45-705. Works
great.

    Speaker output ------[||]--------- Sound card in: 10k side of
   100k side:(bridges ---[||]--------- Ground          xformer
   8ohm.) You can place a res to load the speaker output if you like. I
do not..
 73
Gunther Meisse
W8GSM
-----Original Message-----
From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org]On
Behalf Of Mark L. Hammond
Sent: Saturday, November 10, 2001 12:22 AM
To: amSAT-BB
Subject: RE: [amsat-bb] Re: AO40Rcv and soundboards? ditto


Any chance one of you fellas has a schematic posted on the web somewhere,
and a Radio Shack part number?

Thanks,

73,

Mark

At 05:51 PM 11/9/2001, you wrote:
>At 02:52 08/11/2001 +0000, you wrote:
>>Jim,
>>  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!
>>73
>>Gunther Meisse
>>W8GSM
>>AMSAT LM:594
>>
>>
>>-----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
>Snipped........
>
>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!!!!
>
>FWIW
>
>
>Norm, VK2XCI
>Voice of The Edge of The Outback
>njmcmillan@bigpond.com


Mark L. Hammond  [N8MH]

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