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I built up the 8-pole audio lowpass filter board and it’s waiting to be tested. I also re-worked some of the DC power distribution so the whole receiver up to the audio power amp can be operated seamlessly on either 5V USB power from the Nano (w/no audio power amp) or on 6V-14V external power (w/audio power amp) without any switching.
In the process of doing that I blew up the Nano board and the TFT display board. I have the system back up and running, but with a junkbox TFT display board that doesn’t have touch capability. I have some new display boards on order, but they might take a couple weeks to arrive. Meanwhile, I’m cleaning up some firmware matters. I now have a function to save the whole radio state to EEPROM and automatically restore it on power-up. I also have some GUI cleanup matters that I’ve been putting off.
After repairing my EFHW wire antenna which was knocked down by a concrete truck when I had some work done on my house last year, I was a little disappointed to hear a local 1440 kHz AM station punching through down near the noise threshold. That station runs 5000 watts and is only about 1/2 mile away, so maybe it’s to be expected. It does point to the need for front-end filtering.
Hopefully I’ll get the 8-pole lowpass installed and tested in the next several days.
W3JDR Bright Ideas 
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