[eagle] Re: Receiver Spec vs. ATP, a few Suggestions and aQuestion or Two

John B. Stephensen kd6ozh at comcast.net
Sat Jul 28 16:09:57 PDT 2007


Linear regulators would add 1-1.6 W of power consumption depending on 
battery voltage.

73,

John
KD6OZH

----- Original Message ----- 
From: "Chuck Green" <greencl at mindspring.com>
To: <juan-rivera at sbcglobal.net>
Cc: "'Dave Black (Work)'" <dblack at mail.arc.nasa.gov>; "'Dave Black (Home)'" 
<dblack1054 at yahoo.com>; "'David Smith'" <w6te at msn.com>; <eagle at amsat.org>; 
"'Samsonoff at Mac. Com'" <samsonoff at mac.com>; "'Juan.Rivera (Work)'" 
<Juan.Rivera at gd-ais.com>
Sent: Saturday, July 28, 2007 22:30 UTC
Subject: [eagle] Re: Receiver Spec vs. ATP, a few Suggestions and aQuestion 
or Two


> Hi Juan,
>
> I think the reason you have not seen much regarding the CAN-Do redesign
> is that, as far as I know, no one has stepped up to do the power supply
> redesign.  Until that happens, not much else will happen.
>
> I'm not thrilled with the idea of giving up the switching power supply.
> Remember that the efficiency hit must be multiplied by 10-15, the number
> of CAN-Do's on the satellite.
>
> The "dead-bug" modification is intended to fly.  Those who were not
> around in the early days have no idea what loose wires have flown
> successfully in the past.  That's not to say we should encourage such
> things, just that it's not as ugly to those of us who have seen much
> worse in the past as you might think.  Because of the IC's mass (very
> small) it is probably very secure just the way you see it.  But we will
> also epoxy a radiation shield to it and then conformal coat the whole
> thing with a heave conformal coating which will make it very difficult
> for anything to move.
>
> I'm ready to start a new design (layout) just as soon as someone gives
> us a new power supply design that is quieter, and hopefully, more
> efficient than the 90% we now have.
>
> Chuck
>
> Juan Rivera wrote:
>> Bdale,
>>
>> It would be a trade-off.  I've put out all the information I have and
>> everyone knows my opinions.  I think someone else is supposed to be 
>> looking
>> into this but I forgot who it is since nothing has been posted.  I'd like 
>> to
>> see some alternative suggestions from the experts on the CAN-Do, the
>> enclosure, and the EMI situation in general.
>>
>> By the way, do I have a prototype CAN-Do module or was the intent to fly
>> this version with the dead-bug step-down converter hanging by three leads
>> and a few wires?
>>
>> Juan
>>
>> -----Original Message-----
>> From: Bdale Garbee [mailto:bdale at gag.com]
>> Sent: Saturday, July 28, 2007 2:41 PM
>> To: juan-rivera at sbcglobal.net
>> Cc: 'John B. Stephensen'; David Smith; Dave Black (Work); Dave Black 
>> (Home);
>> eagle at amsat.org; Samsonoff at Mac. Com; Juan.Rivera (Work)
>> Subject: Re: [eagle] Receiver Spec vs. ATP, a few Suggestions and 
>> aQuestion
>> or Two
>>
>> On Fri, 2007-07-27 at 21:23 -0700, Juan Rivera wrote:
>>
>>
>>> 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.
>>>
>>
>> Hrm.  What makes you say "a slight efficiency hit"?
>>
>> Doing this on one or two modules that are particularly susceptible to
>> noise *may* make sense (and I'm certainly open to considering this as an
>> alternative), but we're already on our second power supply design on the
>> CAN-Do! because the original switcher, which was more efficient than a
>> linear regulator, was deemed too inefficient to fly on P3E by our
>> AMSAT-DL friends.
>>
>> Bdale
>>
>>
>>
>>
>> _______________________________________________
>> Via the Eagle mailing list courtesy of AMSAT-NA
>> Eagle at amsat.org
>> http://amsat.org/mailman/listinfo/eagle
>>
>>
> _______________________________________________
> Via the Eagle mailing list courtesy of AMSAT-NA
> Eagle at amsat.org
> http://amsat.org/mailman/listinfo/eagle 



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