Bob,

 

First of all I should warn everyone that I woke up this morning doubting my 11 milliamp CAN-Do power supply load figure.  I was rushed last night and I want to recheck my work.

 

Also in this thread somewhere someone mentioned 0.008" as the max bend per 1" PCB segment.  It's worse than that if you accept the AVX suggestion.  Their number was 0.0038"  I've written all this up in my AMSAT presentation and it's getting peer reviewed at the moment.  I hope to get it out in the next week.

 

Bob,  I think your sketch is more or less what we (the OSCAR group) are suggesting as a solution for the 70 cm Receiver.  I'm not sure it will be a good universal solution, and if that 11 milliamp load ir correct then I think we could just dump the switching step-down converter on the CAN-Do module and completely eliminate the EMI emission problem by going to a linear regulator or tapping power off of the main PCB.  That would side-step a potentially troubesome problem.

 

73, Juan

 

On 7/18/07, Robert Davis <bob2leo@gmail.com> wrote:

I guess I should have finished reading before I send my previous email.

I'm trying to visualize this dual compartment idea which still provides connector face area to both compartments. See attached (as ppt or jpg).

If heat is the issue of the power board, then we can make it a bigger postage stamp as necessary, right? But it would stay in the same compartment as CAN-DO.

At first blush, I think this idea is better than having connections on 2 different walls of the module.

bob

Robert Davis

KF4KSS

 

On 7/18/07, Dick Jansson-rr < rjansson@cfl.rr.com> wrote:

Juan:

 

One difficulty in your suggested "little daughter board" is that while the circuitry may not take much space, getting the cooling of that PCB to the module baseplate may require much more volume and it is restrictive as to where you place this daughter board. In the current design of the URx that is one of the three areas needing the added heat sinks.

 

Dick Jansson, KD1K

kd1k@amsat.org

kd1k@arrl.net

 

From: eagle-bounces@amsat.org [mailto:eagle-bounces@amsat.org] On Behalf Of Juan Rivera
Sent: Wednesday, 18 July, 2007 05.06
To: 'Jim Sanford'
Cc: 'David Smith'; 'Dave Black ((Work))'; 'Dave Black ((Home))'; 'Louis McFadin'; 'AMSAT Eagle'; 'Samsonoff@Mac . Com'; 'Juan.Rivera ((Work))'
Subject: [eagle] Re: Jim's comments

 

(snip)

 

  What if we just disable the CAN-Do module's step-down converter and create a small PCB that would attach to the 40-pin header and be the home for the power supplies for whatever was in the other side of the enclosure – in this case the receiver analog circuitry.  The CAN-Do module would get its power from that little board and so would the receiver.  In the case of this receiver we could put all the power supplies on a PCB about the size of a large postage stamp.

 

1)     

2)    Moves the 157 kHz receiver switching power supply to the separate compartment in the front on that little daughter board and gets rid of that spur in the passband

(snip)

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