Can you "sniff" the various lines from CAN-Do! to get an idea of which is the source?

Also, my memory is that we still have an open issue with the passband ripple -- or did that get resolved and I missed it?

Again, thanks for all you're doing.

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Juan Rivera wrote:



The source of the spurs in the 70 cm prototype receiver is the CAN-Do module.


This is the receiver IF output as designed

(powered from pins 39 and 40 of the CAN-Do Module)



This is the receiver running off of a separate power source

(bypassing the CAN-Do Module +13 volt output on pins 39 and 40)



This is the same configuration as above, but with the CAN-Do module shut down


From the above it appears that:


1.    The CAN-Do module is the source of all the spurs that I see

2.    None of the spurs are being generated by the receiver’s internal power supplies

3.    Some, but not all, of the noise is entering the receiver via the switched +13 volt CAN-Do output on pins 39 and 40

4.    The remainder of the noise could be entering the receiver on other CAN-Do pins, or being radiated to receiver components or traces in close proximity


See my log for all the intermediate steps I took to reach these conclusions.


Remaining RF issues:


1.    Phase noise

2.    Microphonics