All,
Please see my write-up here.
The CAN-Do noise is not lending itself to an easy cure. I think
this whole subject of RFI/EMI needs to be looked at closely. Every payload
will be affected by noise on its inputs and can affect other payloads by
creating noise that is propagated back out from within its module chassis.
With the current scheme, of having a CAN-Do module located in the same
case as the main payload, there are several issues that need immediate attention:
1) The
CAN-Do module provides dirty power – both the +13 VDC output and the
ground are noisy
2) The
CAN-Do’s switching power supply inductor, L3, radiates noise that can
affect sensitive circuits several inches away.
Both of these factors are adversely impacting the 70 cm breadboard
receiver in the form of 5 kHz spurs on the IF output. As I mentions
earlier, Rather than work to clean up the CAN-Do module immediately, we should
focus on making the receiver function In the presence of this noise. This
approach will result in a more robust design. The CAN-Do module needs to
be cleaned up, but for now it acts as a great real-world noise generator.
I’m currently out of ideas. I’d like to hear what you
all have to say.
73,
Juan
WA6HTP