[WriteLog] Hum in Audio

Magnus A sm6wet at telia.com
Tue Apr 6 16:15:45 EDT 2004

Could be so if I get more problems in the future, but so far the mike is
connected directly to the radio not via soundcard.

Will look at your guess later if things work bad then too.


73 Magnus

----- Original Message ----- 
From: <tmcdermott at chiaro.com>
To: <writelog at contesting.com>
Sent: Monday, April 05, 2004 12:28 PM
Subject: Re: [WriteLog] Hum in Audio

> Most soundcards put out more than 1 volt of audio pk-pk. The microphone
input on most rigs
> is setup for about 10 millivolts pk-pk. Thus, the soundcard will overdrive
the mic input by 40 dB !
> This will saturate the audio stages in front of the microphone gain
control, so even if you turn down
> the mic gain, the audio has already been severely distorted. Sometimes its
difficult to turn down the
> soundcard output by so many dB and have it still work well. An attenuator
helps a lot. Two resistors
> in the cable from the soundcard to the mic input, or you can buy an
attenuating audio patch cable
> at Radio Shack PN 42-2152, very inexpensively. See
> for more details.
> -- Tom, N5EG
> > It a bad hum/distortion on my transmitted audio but it does not come
from computer audio. One night I had set up writelog and was
>  > trying to decode som CW and RTTY just for fun, later that evening was a
local 6m contest and using the same FT-920 as I had to
> > decode with I used on the 6m contest. I was getting bad results and
nearby station told me the truth that I sounded distorded or
> > maybee even had a carrier on SSB.
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