[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>
>
>
>
>
>
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> Via the Eagle mailing list courtesy of AMSAT-NA
> Eagle at amsat.org
> http://amsat.org/mailman/listinfo/eagle
>
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