All,
I’ve completed a preliminary evaluation of
the CAN-Do RFI problem.
Please see my log for details by clicking here.
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