[eagle] Re: 70 cm Receiver IF Spurs - Problem Solved
juan-rivera at sbcglobal.net
Sun Jun 17 11:06:45 PDT 2007
I don't want to tear into the CAN-Do module. I feel like it is a loaner and
not mine to modify. It would be interesting to disconnect the switch and
the current monitor from the CAN-Do power input and move it to those user
pins as you suggest. That might just work, but I also know they don't want
to have multiple versions of the module floating around and this would be
We also can't loose sight of the radiated noise from that inductor. I can
see signs of EMI if it gets within 2 inches of the sensitive areas of the
From: Chuck Green [mailto:greencl at mindspring.com]
Sent: Sunday, June 17, 2007 9:18 AM
To: juan-rivera at sbcglobal.net
Subject: Re: [eagle] 70 cm Receiver IF Spurs - Problem Solved
I am impressed with your testing and analysis.
I find it curious that you were unable to filter the power from the
CAN-Do! . But switching noise is notorious for being difficult to
filter. So maybe that is something to just forget. But in a total
system (satellite) it may not be possible to forget. We may need to
find a way to filter the power for sensitive modules even if not using
power from the CAN-Do! ; in which case, such a filter may also filter
the noise from the CAN-Do! .
If your analysis is correct, and it certainly seems to be, then it would
also seem possible to remove the switch from the CAN-Do! (not just
bypass it) and rout your clean power source through the CAN-Do! current
measurement circuit thus saving having to do this in the module.
Great work! And thanks.
Juan Rivera wrote:
> Hi Chuck,
> Bad news I'm afraid. See my report for details... I've sent out a link
> the group.
> -----Original Message-----
> From: Chuck Green [mailto:greencl at mindspring.com]
> Sent: Saturday, June 16, 2007 8:57 AM
> To: juan-rivera at sbcglobal.net
> Cc: eagle at amsat.org; David Smith; Dave Black (Work); Dave Black (Home);
> Samsonoff at Mac. Com; Juan.Rivera (Work)
> Subject: Re: [eagle] 70 cm Receiver IF Spurs - Problem Solved
> Hi Juan,
> This is fantastic!
> Please try one more experiment. Pass the module current through the
> current measuring circuit on the CAN-Do! while bypassing the switch
> transistor (you could just short across the switch transistor) and see
> if the problem reappears.
> If you end up having to use the user pins, you will need to add current
> measuring circuitry to your module. While this is no big deal, its one
> more thing you might not have to do.
> Juan Rivera wrote:
>> The 70 cm Receiver spur problem has been solved. Click here
>> for details.
>> Via the Eagle mailing list courtesy of AMSAT-NA
>> Eagle at amsat.org
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