开云体育

I've been chasing down some noise problems in my bitx40 kit. For a start, my switching power supply is generating a _ton_ of noise. Using a 12V battery fixes that one. Now, when I plug in the Raduino, I immediately get noise very similar to the one presented in this video:?

I'd like to build a simple power supply filter as shown in the video, but I'm not sure where to start. He shows a RC filter in a Pi configuration. Would this go inline between the bitx and the Raduino on the 5 pin cable (P3)??

I'm hoping a filter like this will reduce the noise introduced by the LCD and other components on the Raduino.

Thanks!
David KM4NKU

Are you having trouble with his Australian accent? If not, re-run the video - it's all explained (particularly if you refer also to the hfsigs circuit diagram). His quoting "the DDS" means the Raduino - that's the generic term (Direct Digital Synthesis) - note it's connected to the DDS pins on the BitX main board.
73...

After staring at things for a moment it all makes sense now. Not sure why it didn’t before ?

Any idea if different values could be used for the filter? Could I use a higher value resistor and lower value (say, 33uF) caps?

I'd recommend not going lower on the caps, but resistor might be OK higher. I run at 51E. measure the voltage going into the regulator (the 7805) - don't let it go lower than 7V. A good raduino should be drawing less than 70mA, so 5V drop (12 supply to 7 in) would be about 72E, so 68E (1/2W min.) ought to be safe. I'd also recommend the cap going out of the filter be mounted/connected direct at the 7805, IN to GND (OUT is nearest the contrast pot). I found mine still had a bit of hash (and clicks when changing frequency) at 220uF, so I went to 1000uF (just what I had), and whew! Quiet!.

Good luck and 73 de ZL2DEX

I just watched VK3YE's video and made up the small filter he suggested. I have been trying to reduce the noise on my custom Bitx20 for a while and this small circuit made a huge difference. I attached it between the power supply and the Arduino power input as he suggested and it works really well.

Awesome! I tried it as well with some parts that just arrived. I used 1000uF capacitors and 1W 15 ohm resistors in a second order RC filter, very similar to the video. All the noise from my power supply and the Raduino are totally gone. Woo!

After the holiday I might try to do a write up for the wiki. This stuff might be common knowledge for most builders, but it sure wasn’t for me :)