KH6TY Sound card interface v0.3

Finally took the plunge and reworked the sound card interface. I wanted to make it a little more compact and try to put it into an enclosure.

v0.2 was built on another section of perfboard, but I messed it up and decided to build v0.3 on a piece of half sized Perma-Protoboard.

KH6TY sound card interface v0.3
KH6TY sound card interface v0.3

v0.3 currently half works. Getting sound through from the radio to the laptop seems to be working fine. Getting sound out from the laptop through to the radio doesn’t seem to be working that well though. Seems like there’s not enough voltage into the 2n4711 transistor to make the collector close the PTT line and make the radio transmit. Kind of wondering if I grabbed the wrong diodes that go before the transistor. I also seem to be getting some voltage loss in the 3.5mm connectors. Given how much they’ve been soldered and unsoldered, I should probably find new ones to replace them with.

Still some more hardware debugging to do on this latest iteration.

Update: Electronic devices are weird sometimes. You test them out and they don’t work. Leave them alone for a while, and then they start working. Not sure what it was I did in the sound card settings or in fldigi, but the interface seems to be working now (at least it triggers the PTT when I put fldigi into transmit mode). Now to see if I can actually make a QSO with it.

Update: Successfully made two contacts with the interface! First one was PSK31 with an op in Belgium on 20m and the second one was the W1AW/7 portable station in Idaho on 20m RTTY. Yay!

Instead of mounting it inside a tin, I mounted the board onto another piece of 1×4 lumber with some rubber shelf liner glued to it. It’s kind of neat to see it next to the laptop and imagine the currents flowing around in the circuit while I play.

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