I took a few minutes to look over your new specs and compare them against the Acceptance Test Procedure.  I've got a number of tests in the ATP for which there are no specs:


·         Image rejection

·         Internally generated spurs

·         Local oscillator leakage

·         Input and Output VSWR


Items that need to be addressed that aren’t in either document:


·         EMI conducted susceptibility

·         EMI radiated susceptibility

·         Short and long-term frequency stability


I also take issue with the -60C minimum power-down temperature.  I think this is unrealistic just from a CTE mismatch perspective.  The reliability of anything subjected to that wide a temperature spread is going to suffer.  A way must be found to raise that temperature.


I have a few thoughts...  The CAN-Do switching step-down converter is only supplying 11 milliamps.  If we take a slight efficiency hit we could just go to a simple linear regulator and completely eliminate the radiated and conducted EMI emission problem from CAN-do.  That eases the EMI filtering and shielding requirements for every single payload.  That seems like a good trade-off to me.


Rather than worry about trying to conduct heat through a PCB why not just go to externally mounted regulators for the CAN-Do and the Receiver right on the case itself.  We’re not that pressed for space.  That eases the heat sink and the associated thermal gap filler issues.  EMI will still be an issue, but only for external sources instead of one that is inside the enclosure itself.  That strikes me as a huge bonus.  Why not design a single-sided PCB with the regulators hanging over the edge and the whole assembly, PCB and regulators, mounted directly to the enclosure.  Stick it in with the CAN-Do module in a separate cell.  Filter all the signal and power through the common bulkhead.


I’m also curious as to why you are specifying two different types of SMA connectors.




Juan – WA6HTP