uBitx on JS8Call / FT8

Gordon Gibby
 

Homebrew sound-card isolator  matched to my uBitx today -- ran into unexpected problem:   begin transmission and instead of a solid TX, the push-to-talk chattered in and out of TX / RX / TX / RX about 5 times/second incessantly    


Sound card isolation system is a double transformer, gain pot, vox-type circuit with reed-relay output (https://qsl.net/nf4rc/2019/SmallBoxSoundCardInterfaceManual2.2.pdf and Gerbers are on github) -- so quite puzzled why this happening when never happens with ICOMS..... and the SIGNALINK worked perfectly!


After multiple false theories I finally recognized that the PTT line goes DIRECTLY into a Nano.   Adding a bypass capacitor or two from PTT line to ground (all I had on hand were .047's would have preferred .01) -- and problem solved!!!!   Completely new discovery for me with this design.


The uBitx requires WAY more audio than I'm used to with mic input of ICOmS --had to change the fixed resistor in the audio attenuator to allow 10dB higher signal.    Then it could be adjusted with the gain potentiometer.    


After all THAT, I got it up on JS8 and immediately got 2 answers to my HB signal both giving me reasonable SNR's, and their signals were fine also.    Wandered down to FT8 land....wall to wall signals.   I'll fiddle more with that another day.    


Great rig.   Has taught me a TON -- thanks to you folks!


Gordon KX4Z


Gerbers for the sound isolator:  https://www.qsl.net/nf4rc/Tech/Plated_Through.zip

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