[Elecraft] KX3, FT8, and ALC Question

Don Wilhelm donwilh at embarqmail.com
Mon Oct 23 10:46:07 EDT 2017


Ed,

Perhaps you are driving the audio of the KX3 too hard.  The KX3 has an 
"quirk" that it uses for protection from too much audio by reducing the 
input signal drastically.

Try reducing the soundcard 'speaker' slider and the 'power' slider in 
WSJT-X to see if the audio input level to the KX3 is too great.

If that is the problem, then an attenuator - 10k in series with 1k 
between the audio line and shield - in the line should help.

Remember that the MIC input of the KX3 is microphone level, and you are 
likely driving it with 'speaker' level from the soundcard.  Microphone 
level is in the range of 200 to 600 millivolts while the speaker output 
from the soundcard is in the range of 1 to 3 volts - BIG difference.

73,
Don W3FPR

On 10/23/2017 10:30 AM, Ed G wrote:
> Hello,
>       I have my FT8 software set up, and am using an external E-MU 0202
> soundcard. On the KX3, I am using DATA A, with soundcard output going to the
> KX3 mic input. I have made a couple FT8 contacts.  But the ALC setting
> remains puzzling to me. I have read Don Wilhelm's setup notes for the
> digital modes, but what I am seeing does not agree with the notes. I am
> unable to see any ALC bars. I set power on zero, and essentially set the
> audio input to what sounds good (MIC Gain midscale), then up the power to 10
> watts.
>       If I try to change to the USB mode, the FT8 software switches the KX3
> back to DATA when I click the FT8 Tune button. That may be fine, but no
> matter what I do or how I set the audio input, I don't ever see any bars on
> the ALC meter.
>       Must be something simple I am overlooking?


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