Here is the finished board with the on board Arduino and Si5351 alongside an original uBITX.

Hi! Thank you for your comment and advice. My friend have found the cause of spurious of 75 KHz. He said the cause of spurious was the noise of VCC around 19 MHz of 0.15V. As the result of the

What about the Nextion code Ian?

Hi Akira san, thanks for your update: That's good news, congratulations! This issue may also be related to the strong "birdie" that can be heard at 7199 kHz when the radio is in LSB mode (almost no

Rick, I have a Kees kit and the symptoms are almost exactly as you describe. I don't know that I've heard squeals but otherwise muffled RFI is how I would describe it. Unless Don weighs in with a

Dear Akira, Please share with us the specific details about modifications you used that successfully solved the spurious output problems. Thank you very much and 73 Jerry aa1of

Haha, well, there are always unforeseen complications. On mine, when I open PTT the fan coasts down and I'm guessing acts like a little magnetic generator and puts quite the whir into the AF signal

I really don't have myself setup for portable and I'm on vacation visiting with family in South Carolina so I'm off net for 7 days. 73 Bill WA8VIH/4

Hey Arv, If you try the "snubber" diode, you might put a .1uf or maybe even higher value cap across the diode to help take down the little overshoots that will occur even with the diode in most cases.

Recommendation: Use Allard's v2 firmware and associated hardware mods: https://github.com/amunters/bitx40-raduino-v2 Moving to a high side vfo using Allard's firmware should fix this spur. When

I wondered on that too. Some of C++ features are bulky but for Arduino you don't use them. But it makes building reusable code far easier. Encapsulation is a useful one and I don't see any cost for it

Google "oop and microcontrollers" or "C++ and microcontrollers" . The main reason is the code bloat OOP generates -- Paul Mateer, AA9GG Elan Engineering Corp. www.elanengr.com NAQCC 3123, SKCC 4628

As someone that cut their teeth is the '70s with K&R C the biggest thing I see is poor programming not poor programming languages. I also grew up in systems where resources are scarce and adding

If the problem is feedback from the RF portion of the AGC board back to the AF input, wouldn't a ferrite bead on the Audio input at the AGC board accomplish the same thing without attenuating the

I have this happen, but typically with poor SWR. That would make sense if it is an EMI issue, wouldn't it?

Kees, I tried the clip on beads and if anything it made matters worse- applied to the audio cable. Perhaps multiple turns on a more perfect mixture may help but in reality adding that additional

Did you add the ferrite bead on only the Audio line (not the ground) and was it #43 material ? That's what I would try. But if adding 10nF-15nF to ground which is about 7K at audio frequencies is OK,

Writing that in plain ansi C is just more error prone work than it needs to be. What is your suggestion to fix that? There are elements of C++ that I don't like and tend to be misused (e.g., multiple

Howdy, I am seeking someone close to Atlanta, GA that has a working Bitx-40 "Kit" the one that you just do the final wiring and put the "kit" in a enclosure. My "kit" receives great but does not

Forgot to ask. Did you connect the capacitor across the connector end to ground of C1 or the 2N3904 Base end of C1 to ground ? 73 Kees K5BCQ