Hi Ford,
I have used my v4, v5, and v6 uBITX with WSJT-X.? The interface is 2 600 ohm isolation transformers and ferrites to reduce RF interference.? I use the USB Cat commands to control the uBITX.? Getting the audio level on transmission is key.? I use the CW power reference and WSJT-X Tune to adjust the power to a value at or below the CW reading.
There are kits that others have used, like EasyDigi.? There are numerous available on all of the discount sites.
Many posters have stated that they connect directly to their PC without the transformers without issue.? I have not tried that.
To reduce the "hiss," I returned to the TI datasheet for the LM386.? The first thing I noticed is that HFSignals used a 1mF instead of the 10mF gain capacitor that is suggested.? This limits the low-frequency response of the amp.? There is also a note for Bass Boost that helps as well.? Pick one and try it.? (NOTE: to isolate the LM386 pins, you can bend them parallel to the body of the IC and make the connection there.? LM386s are cheap, and it is better to sacrifice one of them than damage the circuit board.
The digital audio filter is a good device if you want to do CW.? The 2.7kHz SSB filter is too wide for serious CW operation.? There are op amp and other digital files that have been used successfully.? I have made the modes to a couple of uBITX for others as I am not a CW op.
Have fun with your radio!
73
Evan
AC9TU
