RFI from uBitx TX after AGC and other mods installed


RowlandA
 

I just finished installing:
1) ND6T AGC mod using Kees' kit. 
2) AGC off/med/long switch as described in ND6T's instructions
3) T/R LED (Sunil's approach)
4) An RF gain control with an on/off switch so I have front panel on/off using Sunil's enclosure.
5) A wire from J1 to the purple wire on the Digital connector for an S-meter reading

The good news is - no smoke and everything seems to be working.  But now when I transmit (so far just tried SSB), I get very loud RFI (my own garbled voice) in my headphones or speaker, so something I added is getting RF into the system.

I installed the AGC board right at the RF in/out point using the approach outlined by Kees.  I ran RG-174 to the RF gain control, grounded at the RF gain control but not grounded (per instructions) at the AGC board.

I used twisted pair for the runs from the AGC board to the audio gain pot and the +5/ground which I picked up from the green Raduino wire, tapped at the point where the green wire connects to the resistor at the Key jack.  The ground lead twisted to the +5V lead is connected to the ground "bus wire" that connects the front-panel PTT, Phones and Key jacks together.

The wires to select AGC hang time from the front panel switch are not twisted together.

Everything is connected to the AGC board using header pins and plug-in wires so I can disconnect easily from the AGC board, but not easily from the other end of the wire(s).  

Is there an obvious place to start troubleshooting this and/or since I'm already using coax and twisted pairs as recommended in ND6T's instructions, thoughts on a fix?

73,

Rowland K4XD

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