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Hi All,?
I've been doing a lot of testing on the transmitted audio and getting a lot of RF on my signal above 5W or so.?
Has anyone experienced this?? ?I have been changing supplies, things like that but even on the best supply it seems to be there.?
If nobody has experienced that I would like to know that.?
If many have I wonder what has been done. This bitx20 channel has all sorts of information on it but I find it hard to sift through jumping in the middle like I have.?
Anyway, let me know
73 Brad?
N8YG

H Mike, resonant antenna 1:1 and same with dummy load. thanks for the reply. This is a fully completed model. Not the kit.. Not sure if it's worth revisiting the bias settings or if there is just modulation of the mic input somehow.. The 2 tone test works fine without distortion I guess since it is generated by the pi in digital mode to the codec. But the mic input is being distorted. I will dig into this at some point soon, but just need to gather information before doing anything. I love this radio, in fact if I can get this problem resolved it will be my main rig. (also have ten tec omni VII, IC-7300 and ubitx rev 5 with ssm2167 compression that makes it an amazing rig).?
73 Brad N8YG

ok, not Mike, Max.. sorry

I've noticed that C31 is missing from my circuit board which looks lo be a local power puddle reserve for U5 the LM380 amplifier. Is this normal? Also is there a layout/parts placement to help me with debug? I did not see this on github, but maybe it's not available so the board is not copied... which I get. Even a parts placement would help.?

A pic of c31 missing.?

Thanks Farhan, just doing my due diligence making sure everything is correct before jumping in further.

I'm keeping this alive in case anyone runs into this issue. Here is an audio recording from k3fef web sdr.?
I start at 5w and it doesn't sound too bad.. noisy because of the low power but otherwise fine.. then go to 15w and you can hear the distortion clearly.
I didn't build this so taking my sweet time to dig into it LOL.?
I have an aversion to doing it because otherwise having a blast playing with it.?

I have a problem that is similar and may be the same. Will be digging into this more later.

Got an audio report that said it sounded distorted. The mic is the one that came in the uBitx v3 kit.

Will try to get an audio recording to compare.?

Thanks Kc5wz. Yeah, it looks like the 2 tone test audio is not distorted nor is the ft8.. so probably just in the simple mic input amp area.. but that's just drive by debug.. as we used to say at work...?
Brad

Brad,

I would also look at possible RF feedback.? You could try using a dummy load for the sBitx antenna and monitor on a radio in the shack.? If you have some snap-on ferrites, try those on the mic cable.

73
Evan
AC9TU

Thanks Evan, I have done all that.. and more..it seems that the issues is only related to the mic input.. but happens if on dummy load or 1:1 antenna, with various power supplies.. etc. The 2 tone test does not seem to corrupt, nor does the ft8 signal, so I guess it's in the mic input chain. Which I think I'm going to wait on this a bit to see what the fix is for the tx power before jumping on the circuit board with fixes. BTW my resonant antenna is 300 ft to the back yard.. so I've never had rf in the shack.. It's kind of nice that way.. :-)
73 Brad