All,
I've completed a preliminary evaluation of the CAN-Do RFI problem. Please see my log for details by clicking here http://www.juanr.com/pages/hobbies/ham_radio/Eagle/CAN-Do_Noise_Troubleshoo ting.htm .
Preliminary Findings...
1. The spurs seen in the receiver IF enter the receiver in two ways
o As radiation from the CAN-Do inductor
o Via CAN-Do module switched +14 VDC power on pins 39 and 40
2. I/O line filtering appears to be unnecessary
3. The switched power from the CAN-Do module pins 39 and 40 must be filtered
4. The CAN-Do module will either have to be kept physically separated from any sensitive components, redesigned, shielded or a combination of the three.
5. Moving the Can-Do module 2-1/4" forward of its normal location on the receiver PCB lowers the EMI level below the noise floor.
Suggestions...
* Create a full size PCB for the next generation receiver and shift the RF components to the back of the board (away from the CAN-Do module.)
* Add DC input filtering to the receiver
73,
Juan
WA6HTP