[RFI] DigiKeyer II

[CR]

There is an RFI modification for Microkeyer II's below SN 765 that might 
help.
See http://www.microham.com/contents/en-us/d143.html

Excerpt:
"Those who are experiencing RFI in the microphone circuit can add 
bypassing in the field by installing a 0.001 - 0.01uF high voltage 
capacitor (the value in not critical) from the shield of the USB 
connector to the metal mounting bracket of the DB37 connector as shown 
here."

I do not own any of these products.

Cortland
KA5S