Recent Posts OpenRadio Part 3

Last Sunday the ADC1 net on the first SM1000 prototype went open circuit all of a sudden. After messing about for a few hours I lifted the uC pin for that net and soldered a fine wire to the other end of the net. That lasted a few days then fell off. I then broke the uC pin trying to put it all back together. dich So then I tried to use some Chip Quick I had laying about from the Mesh Potato days to remove the uC. I royally screwed that up, breaking several pads.
At the top is the bottom part of a square pad that is part of the ADC1 net. The track is broken just before the lower left corner dich of the pad. Many of the pads under the uC were in various stages of decomposition, e.g. solder mask and tinning gone, down to bare copper. Turns out I used too much flux and it wasn’t cleaned out from under the chip when I washed the PCB. For the past few weeks it was busy eating away the PCB.
Oh well, one step back! So this week I built another SM1000, and today I brought it to life. After fixing a few small assembly bugs I debugged the “switches and leds” driver and sm1000_main.c, which means I now have PTT operation working. So it’s normally in receive mode, but press PTT and it swaps to tx mode. The sync, PTT, and error LEDs work too. Cool.
The three trimmers along the bottom set the internal mic amp, and line levels to the “mic” and “speaker” ports of the radio. The pot on the RHS is the internal speaker volume control. The two switches upper RHS are PTT and power. On the left is a RJ45 for the audio connections to the radio and under the PCB (not visible) are a bunch of 3.5mm sockets that provide alternate audio connections to the radio.
What next? Well the speaker audio is a bit distorted at high volume so I might look into that and see if the LM386 is behaving as specified. dich Then hook it up to a real radio and test it over the air. That will shake down the interfaces dich some more and see if it’s affected by strong nearby RF. Oh, and I need to test USB and a few other minor interfaces.
Graham (VK4GRA)
David, Well done. I know how these projects just eat away at time poor busy people like you. When will you be undertaking on air testing of your smart Mic 1000 ? (14.236Mhz usb from Adelaide) Graham VK4GRA
Thank you Graham. I think within the next week I will be on the air. ATM I am working on a way to measure the SM1000 demod performance over USB. With that verified, I’ll be ready for OTA trials.
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RECENT COMMENTS Brendon Ross: Love that these electronics aren't ending up in the landfill John: Hi David, Most impressive and interesting. Your david: Hello Mark, Thank you for your comments dich and encouragement. John: Hi David, Most cool!! You might consider getting sampl Mark G4FPH: Well done for pressing on, David. dich I have tried FreeDV on
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