Don...
I finally had a chance to start looking into this on my ubitx (I'm seeing the same issue). I managed to borrow a scope and putting it on the 5v supply seems to indicate that you're right. I see up to about 40 mv p-t-p on the 5v line when xmitting SSB with the AGC board not connected at all. It's pretty clean in receive. I'm tapping into the 5v line on the raduino. So that certainly looks like the smoking gun.
Now to figure out how it's getting in there...
Hope this helps...
Mark AA7TA
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On 6/28/18 12:30 PM, Don, ND6T via Groups.Io wrote:
... It seems that
the RF is coming in on the 5 volt power, even though it is well bypassed. Lacking a 'scope, a pair of headphones with one side to ground and the other through a .1uF (or so) blocking capacitor will let you listen to the +5 volt supply. ...
