[WriteLog] Hum in Audio

[tmcdermott at chiaro.com]

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  http://www.tapr.org/~n5eg/index_files/page0005.html
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.