[eagle] Re: Module Temperatures

Jim Sanford wb4gcs at amsat.org
Sat Sep 1 02:22:37 PDT 2007


John:
If you have a final LO design, it would seem appropriate to route (or 
announce posting of a paper) and convene a formal Peer Review.  We can 
use that to force the discussion and decision.

Question:  Do we have a chance of getting a handle on the passband 
ripple in time to use the board as the downconverter for our demo at 
Symposium?

Thanks & 73,
Jim
wb4gcs at amsat.org


John B. Stephensen wrote:
> Since the jumps were due to frequency corrections in the digital TCXO, 
> you could make a recording using an external frequency reference. I'd 
> like to make sure that everyone agrees with the current LO design 
> before doing rev. B.
>  
> 73,
>  
> John
> KD6OZH
>
>     ----- Original Message -----
>     *From:* Juan Rivera <mailto:juan-rivera at sbcglobal.net>
>     *To:* 'John B. Stephensen' <mailto:kd6ozh at comcast.net>
>     *Cc:* 'Dick Jansson-rr' <mailto:rjansson at cfl.rr.com> ; 'AMSAT
>     Eagle' <mailto:eagle at amsat.org>
>     *Sent:* Saturday, September 01, 2007 00:56 UTC
>     *Subject:* RE: Module Temperatures
>
>     John,
>
>      
>
>     I never made the WAV file since the IF output was jumping in
>     frequency every few seconds.  I have several .WAV files of those
>     jumps in my log on EaglePedia.
>
>      
>
>     Once you get the SAW filters dialed in I'd like to do a
>     temperature run and see how they act over temperature since they
>     seem to be so sensitive to matching.
>
>      
>
>     Juan
>
>      
>
>     ------------------------------------------------------------------------
>
>     *From:* John B. Stephensen [mailto:kd6ozh at comcast.net]
>     *Sent:* Friday, August 31, 2007 4:51 PM
>     *To:* Juan Rivera
>     *Cc:* Dick Jansson-rr; AMSAT Eagle
>     *Subject:* Re: Module Temperatures
>
>      
>
>     If the first prototype behaves during the thermal testing, it will
>     ensure that any copy of rev. B will work. The first mixer is the
>     hot spot and that will remain the same. Unless anyone objects to
>     the latest requirements document, the power dissipation will go
>     down by 1/2 Watt in the rest of the board.
>
>      
>
>     I just received an assortment of 2% inductors from muRata, so I'll
>     be able to optimize the matching network and use a 2 pF trimmer
>     for fine tuning.
>
>      
>
>     Did you ever make a .wav file for Phil Karn? He wanted a recording
>     of a CW signal for evaluating phase noise. Since it's narrow band,
>     it won't be affected by the passband ripple.
>
>      
>
>     73,
>
>      
>
>     John
>
>     KD6OZH
>
>      
>
>         ----- Original Message -----
>
>         *From:* Juan Rivera <mailto:juan-rivera at sbcglobal.net>
>
>         *To:* John B. Stephensen <mailto:kd6ozh at comcast.net>
>
>         *Cc:* Dick Jansson-rr <mailto:rjansson at cfl.rr.com> ; AMSAT
>         Eagle <mailto:eagle at amsat.org>
>
>         *Sent:* Wednesday, August 29, 2007 19:54 UTC
>
>         *Subject:* Re: Module Temperatures
>
>          
>
>         John,
>
>          
>
>         We're working on a plan to get some thermal/vacuum testing in
>         on the first prototype.  If we can get this together in a
>         reasonable time I'd like to do that before you get too far
>         into the PCB design for the next rev in case there are some
>         thermal surprises.  I'll keep you posted on our progress...
>
>          
>
>         Juan
>
>          
>
>         On 8/28/07, *John B. Stephensen* <kd6ozh at comcast.net
>         <mailto:kd6ozh at comcast.net>> wrote:
>
>         If we can keep the SAW filters above -35 C there should be no
>         problems.
>
>          
>
>         As soon as I can get the a problem with the Gerber files
>         solved, I'll prototype the adjustable SAW filter matching
>         network. After that, the rev. B PCB can be created.
>
>          
>
>         73,
>
>          
>
>         John
>
>         KD6OZH
>
>             ----- Original Message -----
>
>             *From:* Juan Rivera <mailto:juan-rivera at sbcglobal.net>
>
>             *To:* Dick Jansson-rr <mailto:rjansson at cfl.rr.com>
>
>             *Cc:* John Stephensen <mailto:kd6ozh at comcast.net> ; AMSAT
>             Eagle <mailto:eagle at amsat.org>
>
>             *Sent:* Tuesday, August 28, 2007 20:05 UTC
>
>             *Subject:* Re: Module Temperatures
>
>
>              
>
>             Dick,
>
>              
>
>             That's fantastic news and will make a huge difference in
>             my ability to get a sound night's sleep!  As you know, the
>             SAW filters in the existing 70 cm Receiver are rated at a
>             minimum operating temperature of -35C and the minimum
>             storage temperature wasn't much lower.  This should mean
>             that John can return to a one PCB design instead of having
>             to split the receiver into two separate enclosures.
>
>              
>
>             73,  Juan - WA6HTP
>
>              
>
>             On 8/28/07, *Dick Jansson-rr* <rjansson at cfl.rr.com
>             <mailto:rjansson at cfl.rr.com>> wrote:
>
>             Juan & John:
>
>              
>
>             I have finally been able to achieve some analytical
>             results for projecting the temperatures of Eagle modules
>             after two hour and three hour eclipse periods of no-solar
>             heating. This has taken some time as I was struggling with
>             the proper use of the SINDA software and had to call for
>             some help -- which is why we pay money for the license, it
>             comes with help when needed. (I should also note that with
>             modern versions of this software and a pricey, but fast
>             and capable, Dell computer, these analytic runs only
>             required 18 seconds of real run time!)
>
>              
>
>             Nevertheless, I have been able to get some believable
>             modeling results. The spacecraft model used is what I now
>             call "Small Eagle", the formerly proposed, but rejected
>             600x600x435mm spaceframe structure. While this is not as
>             large as our currently planned hexagonal structure, the
>             equipment bays are just about the same size as the larger
>             spaceframe. I ran the model with one of the E05 20,
>             125x180mm, modules with coatings with an effective
>             emittance of about 0.45, rather than 0.04, as would have
>             to be done for the URx module. There was essentially no
>             power dissipations in any module, at the most about 20mW
>             in a few modules. This is granted to be an abnormal
>             situation, but I wanted to see what happens. A later run
>             was made with only a total spacecraft power dissipation of
>             only 7mW were only lower by 0.1°C to 0.2°C lower temperatures.
>
>              
>
>             Modules started out at temperatures of +20°C and the
>             spaceframe core structure at +10°C. The propellant tank
>             was empty so it did not contribute any large thermal mass
>             to delaying the cool-down. After two hours of eclipse the
>             module temperatures were - 5.2°C to -5.4°C (with the high
>             emittance module being cooler), and after three hours of
>             eclipse the module temperatures were -15.9°C to -16.2°C.
>             The spaceframe core structure (equipment panels) were down
>             to -10.2°C and -19.4°C respectively. For these cooling
>             periods, the spacecraft outer skin temperatures ranged
>             from -35°C down to -55°C. The deployed solar panels became
>             a bit chilly, down to -113°C.
>
>              
>
>             A subsequent SINDA run was made with some kind of useful
>             power dissipations in modules -- 0.5W to 1.0W -- not large
>             but supposedly enough to keep things from getting out of
>             hand, and with a total spacecraft dissipation of 16.5W.
>             The two hour eclipse temperatures ran from -3.4°C (1.0W)
>             to -3.9°C. In three hours of eclipse the module
>             temperatures were at -13.3°C down to -14.0°C. In other
>             words, these levels of power dissipation did not
>             significantly warm the modules. The spaceframe core
>             temperatures were at - 8.0°C and -16.3°C respectively.,
>             just a few degrees warmer.
>
>              
>
>             What this data tells me is that specifying the "cold"
>             temperature of a module does not have to be much lower
>             than -20°C, and if it is operating at all they can be only
>             a little higher. Cold module temperatures certainly do not
>             need to be in the -60°C range. Beyond these statements, I
>             shall not presume to be a specification writer.
>
>              
>
>             '73,
>
>             Dick Jansson, KD1K
>
>             kd1k at amsat.org <mailto:kd1k at amsat.org>
>
>             kd1k at arrl.net <mailto:kd1k at arrl.net>
>
>              
>
>              
>
>          
>
> ------------------------------------------------------------------------
>
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