Re: Debug question regarding FT8 and KD8CEC cat control #ubitx

Nikos SV1IYF
 

Hi Tom and Doug,

My setup is as follows:
1) Stand alone ADC (Edirol UA-5) is driven by line level analog audio, tapped-off at the ends of the volume potentiometer.
This interconnection a) eliminates any distortion introduced by the audio amplifier and b) the digital audio level is fixed.
On a side note, the original AF amplifier lasted only a couple of hours. It is now replaced.
2) Analog audio from my laptop is used for TX modulation connected to the mic jack.
3) Frequency and Tx control via cat.
When the cat cable is in place a high pitched frequency is heard and it is also visible overlayed on the JTDX witerfall  (banded spectrum).
Disconnect the USB cable and it goes away.

73 Nikos

 On 6/4/2018 5:24 μμ, Doug W wrote:
Are you getting any noise connecting your audio lines direct to your computer?  Trying digital modes is on my project list and I always assumed I would need coupling transformers.  I saw your response to Nikos regarding cross talk from the CAT connection but I was wondering about hum or ground loops or any other dirtiness on the signal.  Do you have any means of measuring noise or are you going by ear?

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