开云体育

Everyone.
I have a BITX 40 who is plagued with the frequency shift problem during transmit . I know there was answers to this problem on this list list before. I understand their was a solution to this problem using hardware only not needing to load new sketches. Could someone enlighten me on this hardware change. Thanks so much
73
Dave KD1NA?

I doubt there's a hardware fix that solves this, best to figure out how to load one of Allard's sketches:
? ??github.com/amunters/
The bitx40_raduino_v2 is more capable than the original bitx40 branch, but v2 has slightly more hardware mods required.

You can try adding 0.1uF caps at both ends of the cable from tuning pot to raduino, not just one end.
Goes from the middle pot pin to ground.? Also, do what you can to make the 5v coming out of the LM7805 regulator
sticking out the side of the Raduino as stable as you can.? And perhaps add some caps from 5v to ground on
that cable out to the tuning pot for good measure.

The issue is that the original Bitx40 code reads the voltage of the tuning pot using a (relatively coarse) 10 bit ADC,?
and then loads up the si5351 accordingly.? The analog signal coming into the ADC is a bit noisy,
so even when not transmitting it will jump around some.? Allard's code reads the pot many times
and takes an average.? Allard also avoids random wandering about, and locks the frequency during transmit.

Jerry, KE7ER

David :?

You did remember to install the 0.1 uF disc cap across the tuning pot (where the yellow and violet wires attach) ??

Michael VE3WMB?

P.S. I do also recommend upgrading the Raduino to use PE1NWLs code (it is backward compatible with the original code) as it will
give you a better tuning experience and will prevent any "FMing" on TX.?

I agree on changing to Allard's code. It is a wonderful improvement to all aspects of the BitX40 and works even without any hardware mods. Loading a new sketch is easy. I had no experience with Arduinos or anything like that and following the "Raduino Software for Geezers" instructions (Google it) I was able to upload and experiment with changes to the sketch. For best results you'll need at least one pushbutton switch to get access to the function menu, and make one small addition running a connection from a well-illustrated location back to the Raduino so it will know when you are in transmit, but those changes just add features like being able to scan, switch VFOs, work split, etc., and the sketch will work better than the OEM sketch right out of the box with no changes at all.

As another aside, for guys just building their BitXs. Look where the USB port is on the Raduino. Almost every build I see puts the tuning pot right in front of it so you can't get at it to change software. Mount the Raduino to the right (facing) side of your front panel and you'll have easy access to the port and have as much fun playing with sketch changes as with other aspects of the rig.

=Vic=