Team:
Our next TS conference will be Tuesday night at 2100 EST, 1800 PST, 0200
ZULU.
The agenda is posted on the TeamSpeak conferences page of EaglePedia.
Please add to it and join us Tuesday night.
Note: I'll be travelling to VA and the weather is looking ugly (to be
kind), so I might be a few minutes late. If I don't show up, please
press on and take good notes.
Thanks & 73,
Jim
wb4gcs(a)amsat.org
Hi everyone,
This seems to be a quiet week for general AMSAT and satellite info for the
ANS Bulletins. Perhaps its an opportunity to provide a shot of longer range
information about what AMSAT is up to?
1. Anything that can be said about Eagle?
2. Anything that can be said about the New Lab or University projects?
3. Anything that can be said about P3E?
4. Plans for Dayton?
5. Early info for the next Symposium?
If you have anything please send the info to me by Saturday afternoon? I'll
get it formatted into the final form for the bulletins ... just having the
info helps the ANS editors a lot!
Thanks!
--
73 de JoAnne K9JKM
k9jkm(a)amsat.org
Editor, AMSAT News Service
John:
Per your suggestion, I have examined your data for the U band Receiver. I
shall first examine the power supplies for the receiver. The data that I
have elicited from your information is as follows, powers in Watts:
Device Dissipation Delivered
U16 0.340 0.850
U17 0.411
U18 0.384 1.200
U19 0.108 0.090
U20 0.040 0.224
------------ ------------
Totals 1.283W 2.364W
For a grand total power dissipation of the power system of 3.647W. Of the
delivered power you have identified two devices that suck up (U2 = 0.490W
and U3 = 0.388W) a total of 0.878W. It is not clear where the remaining
1.486W is dissipated. Your help in identifying where this thermal energy is
dumped in the module would be helpful, just to make sure that no stone
remains unturned in this matter of handling these dissipations. Hot
resistors could be an issue of concern......
You talk (somewhat glibly) of sinking regulator devices to PCB copper pads
and such. For at least five devices, U2, U3, U16, U17, & U18 I consider that
such mounting is not acceptable as such concentrated dissipations,
exacerbated by the vacuum environment, must be treated more specifically in
achieving heat sinking to the module housing. The module Base Plate, drawing
E05 21, being of somewhat robust 1.6mm thick aluminum should help
significantly in dissipating these module powers. More direct thermal
coupling methods are going to be needed in this module to get that heat to
the Base Plate. PCB thermal conductivities, even enhanced by added copper,
are not good at all and cannot really be depended upon in these situations.
With this module "pushing" the envelop of module power rating, baring a full
heatsink module, it is clear that the coatings of the module will not be
bare aluminum. This raises the ante in the picture of keeping command-level
modules from getting too cold in the eclipse situation. The original concept
for maintaining full control of the spacecraft through a 3 hour eclipse,
where the spaceframe can be as low as -130°C or lower, low power,
command-sensitive modules would not become dangerously cold, provided that
their dissipations are indeed low and the thermal coatings highly
reflective. If on the other hand we depend upon higher dissipation modules,
such as this URx, then the module temperatures may be a concern in the
eclipse situation. This is all subject to detailed analytic examination upon
the construction of a full spacecraft analytic model, which we do not have
at the moment, we first need a detailed mechanical design before having that
analytic model.
In any event, this URx presents a significant thermal challenge. Solving
this challenge first needs an understanding of the physical bodies of these
devices of the forenoted concern. Can you provide me with the physical
information on these devices, either directly or by URL? Can you also
respond to my earlier question on where the rest of the power dissipation
resides? By one means or another we need to engineer a more direct thermal
connection between these devices and the E05 21 Base Plate, which may
require some inventiveness of our collective crania.
'73,
Dick Jansson, KD1K
(ex: WD4FAB)
kd1k(a)amsat.org
---------------------------
I had pizza with Brian Kantor WB6CYT Saturday night. He said somebody in
AMSAT, possibly Rick, had asked for root access for the amsat.org
machine so that various new functions could be added.
I wasn't sure (and neither was Brian) of the specific new functions to
be added, but they seemed to be various forms of engineering support.
Brian is concerned, and I agree with him, that these additions might
risk the stability and security of a stable machine already relied upon
very heavily by everyone in AMSAT for email reflector and web services.
Problems might come from the new services themselves, or from the much
larger set of administrators with root access that would surely result.
For example, counter to the assumptions of some, the amsat.org machine
doesn't run Linux; it runs BSD Unix. They're similar in many ways, but
there are crucial differences that anyone with root access must be aware of.
Computers, even rackmount servers, just aren't so expensive or hard to
come by that we have to cram everything on a single box. If there's need
for another new server to handle AMSAT engineering-related services, I'm
sure we could come up with a new box and host it at either UCSD (where
Brian would manage it) or Qualcomm (where I would manage it.)
Just let me know what's really needed, and we can make it happen.
Phil
This is a repeat of the earlier e-mail.
Here is a proposal for arranging the Eagle antennas that Stan Wood
and I worked out today.
By moving the 2M dipoles to the corners we have sufficient room for
full sized elements over the ground plane. The 2M antennas should get
about 8dB.
Three L band patches in cavities should give us greater than 12 dB gain.
By putting the S1,S2 and C band patches in hex shaped cups we
maximize the available space. The cup arrays can be NC machined out
of a solid blank and therefore attain precise control of the spacing.
It may also serve as heat a radiating device. Each patch will be
circular polarized and fed with a single feed from it's matching
amplifier.
The 70 CM Circular polarized patch should have around 6 dB gain. We
will look at getting more gain on 70 cm. Seven S1 patches will be
mounted on top the 70CM patch. They should get about 15dB gain.
Tom's S2 interferometric patches are included.
Omni antennas similar to that used on P3D will be required on the
opposite side of the spacecraft.
There should also be room for the Sun Sensors on both sides of the
spacecraft.

Lou McFadin
W5DID
w5did(a)mac.com
_______________________________________________
Via the Eagle mailing list courtesy of AMSAT-NA
Eagle(a)amsat.org
http://amsat.org/mailman/listinfo/eagle
Lou McFadin
W5DID
w5did(a)mac.com
(Repeated from earlier since I did not see a return note)
I regret very much not being with you tonight. I am in Boston trying to
not get snowed in with Eric Blossom and others taking Cell processor
training from Mercury. We left dinner long after the TS started because
we left work long after the TS started!
The Cell processor is a fascinating thing and has the potential to be a
really disruptive technology but it is tedious to program.
73's
Bob
N4HY
--
AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL,
TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair
"Taking fun as simply fun and earnestness in earnest shows
how thoroughly thou none of the two discernest." - Piet Hine
Lately I have not been receiving Eagle email, owing to shifts in addresses
that I was assured did not make for problems. For the moment, please add
kd1k(a)amsat.org to your submissions to Eagle mail. Thanks.
Dick Jansson, KD1K
(ex: WD4FAB)
kd1k(a)amsat.org
---------------------------
I regret very much not being with you tonight. I am in Boston trying to
not get snowed in with Eric Blossom and others taking Cell processor
training from Mercury. We left dinner long after the TS started because
we left work long after the TS started!
The Cell processor is a fascinating thing and has the potential to be a
really disruptive technology but it is tedious to program.
73's
Bob
N4HY
--
AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL,
TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair
"Taking fun as simply fun and earnestness in earnest shows
how thoroughly thou none of the two discernest." - Piet Hine
