[eagle] Re: Preliminary CAN-Do EMI Findings and Suggestions to Mitigate in the 70 cm Receiver

Jim Sanford wb4gcs at amsat.org
Fri Jun 15 05:20:35 PDT 2007


Juan:
As usual, good work, and well documented -- thanks!

What is your plan for proceeding to execution of the ATP?

After you've developed a test configuraton and executed/documented the ATP,
I'd like to see a single document, titled "Recommended changes to 
design," which would be the single summary of all you've learned and 
would recommend we do different in this design.  As always, I'm open to 
a better idea.

THanks & 73,
Jim
wb4gcs at amsat.org


Juan Rivera wrote:

> 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_Troubleshooting.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
>
>------------------------------------------------------------------------
>
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>  
>
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