- Eagle (INACTIVE) - mailman.amsat.org

CAN-Do noise problem is proving to be a difficult one to fix
by Juan Rivera 18 Jun '07

18 Jun '07

All, Please see my write-up here <http://www.juanr.com/pages/hobbies/ham_radio/Eagle/CAN-Do_Noise_Troubleshoo ting.htm> . The CAN-Do noise is not lending itself to an easy cure. I think this whole subject of RFI/EMI needs to be looked at closely. Every payload will be affected by noise on its inputs and can affect other payloads by creating noise that is propagated back out from within its module chassis. With the current scheme, of having a CAN-Do module located in the same case as the main payload, there are several issues that need immediate attention: 1) The CAN-Do module provides dirty power - both the +13 VDC output and the ground are noisy 2) The CAN-Do's switching power supply inductor, L3, radiates noise that can affect sensitive circuits several inches away. Both of these factors are adversely impacting the 70 cm breadboard receiver in the form of 5 kHz spurs on the IF output. As I mentions earlier, Rather than work to clean up the CAN-Do module immediately, we should focus on making the receiver function In the presence of this noise. This approach will result in a more robust design. The CAN-Do module needs to be cleaned up, but for now it acts as a great real-world noise generator. I'm currently out of ideas. I'd like to hear what you all have to say. 73, Juan WA6HTP

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Preliminary CAN-Do EMI Findings and Suggestions to Mitigate in the 70 cm Receiver
by Juan Rivera 18 Jun '07

18 Jun '07

All, I've completed a preliminary evaluation of the CAN-Do RFI problem. Please see my log for details by clicking here <http://www.juanr.com/pages/hobbies/ham_radio/Eagle/CAN-Do_Noise_Troubleshoo ting.htm> . Preliminary Findings... 1. The spurs seen in the receiver IF enter the receiver in two ways o As radiation from the CAN-Do inductor o Via CAN-Do module switched +14 VDC power on pins 39 and 40 2. I/O line filtering appears to be unnecessary 3. The switched power from the CAN-Do module pins 39 and 40 must be filtered 4. The CAN-Do module will either have to be kept physically separated from any sensitive components, redesigned, shielded or a combination of the three. 5. Moving the Can-Do module 2-1/4" forward of its normal location on the receiver PCB lowers the EMI level below the noise floor. Suggestions... * Create a full size PCB for the next generation receiver and shift the RF components to the back of the board (away from the CAN-Do module.) * Add DC input filtering to the receiver 73, Juan WA6HTP

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AO-51 received signal strength survey
by Andrew Glasbrenner 18 Jun '07

18 Jun '07

Gentlemen, Gould and I are planning on running a survey with the SQRX on AO-51 during the V/S session at the end of the month. In the past I have created signal strength maps for the earth that show the RF levels seen at the satellite. Would this be useful for any planning for Eagle or P3E? We were thinking we could listen at L band or in the proposed Mode B uplink window. 73, Drew KO4MA

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Power Grounds
by Bill Tynan 17 Jun '07

17 Jun '07

Juan Rivers wrote in part: I've been thinking about DC power distribution in general. Can someone explain the plan for Eagle to me? In aircraft, at least in the one I am familiar with, they do not use the chassis as a return. All DC power is treated the same way as AC power and distributed from a common point as a twisted pair to minimize common mode noise. Great care is taken to eliminate ground loops by insuring that the ground returns are back through the twisted pair to the source and not through a sneak path to the frame. I agree. This is the way it was in the missile business when I worked on Tomahawk, Standard Missile and Talos from the 50s thru 1988. 73, Bill Tynan, W3XO Now back on the Eagle list. Thanks Jim & Paul.

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Cool Model
by Dick Jansson-rr 17 Jun '07

17 Jun '07

Bob: I have done some experimental work with a satellite in the eclipse mode of cooling using the currently active P3E files. The results are a little bit tongue in cheek, but I shall report them nonetheless as these results may help the Eagle team. The reason for my caution is that some of the results are a bit uncertain in my mind, but useful to others. The P3E model had the sun "turned off" for a 2 hour period and pretty well powered down save for a command receiver, a beacon transmitter, and the IHU. The geometry of these modules, and their placement in the P3E spaceframe, bears no resemblance to the Eagle modules, which certainly is a point of caution. The results of these analyses, one with propellant (a very substantial thermal mass) and one without the propellant. I shall report two temperatures, one for the model with propellant and the other without the propellant. Solar panels really get chilly, as expected, as do the internal equipment panels. So here goes, all temperatures in degrees Celsius: Solar Panels: -45.7/-51.6 Equipment Panels : -22.6/-29.5 Top & Bottom Panels: -30.0/-36.6 Central Cylinder: -10.7/-26.7 L Receiver: 0.0/-2.0 U-V Transmitter: -12.2/-14.2 I shall not report the IHU temperatures as I don't believe them and have not yet been able to understand them. The LRx was dissipating 2.0W while mounted on top of a box dissipating 0.4W, the U-V Tx dissipating only 2.0W, with a total dissipation of only 6.2W. The power dissipation is modest but so to is the P3E battery energy. What these numbers tell me is that there is hope that the Eagle equipment would not even see -20°C, but I feel that -30°C should be used as a bottom limit number. This caution is based on the fact that the Eagle geometry is not nearly as closely packed as is P3E. Dick Jansson, KD1K <mailto:kd1k@amsat.org> kd1k(a)amsat.org <mailto:kd1k@arrl.net> kd1k(a)arrl.net ---------------------------

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70 cm Receiver IF Spurs - Problem Solved
by Juan Rivera 16 Jun '07

16 Jun '07

All, The 70 cm Receiver spur problem has been solved. Click here <http://www.juanr.com/pages/hobbies/ham_radio/Eagle/CAN-Do_Noise_Troubleshoo ting.htm> for details. 73, Juan WA6HTP

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latest 70 cm Receiver test results
by Juan Rivera 15 Jun '07

15 Jun '07

All, I've posted my latest 70 cm Receiver test results here <http://www.juanr.com/pages/hobbies/ham_radio/Eagle/CAN-Do_Noise_Troubleshoo ting.htm> . I'd been guilty of tunnel vision. See my log for new details. 73, Juan WA6HTP

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Preliminary Findings - CAN-Do Module Noise
by Juan Rivera 14 Jun '07

14 Jun '07

All, Please see the usual location for my preliminary CAN-Do noise test results - Look for CAN-Do Noise Troubleshooting in the Eagle Receiver page, or go to my web at http://www.juanr.com and drill down in the menu, through ham radio, to AMSAT Eagle, to CAN-Do Noise Troubleshooting. It's about 100F in my shack at the moment so I'll trust you to find the preliminary report there so I can clear out of here and cool off. I intend to dig into this in much more detail once it cools off... 73, Juan WA6HTP

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Apologies, status
by Robert McGwier 13 Jun '07

13 Jun '07

Until a) The Flex 5000 comes out, b) June 27 arrives and my summer project starts at work, c) Linux version of Tac32 works and clock steering algorithms in CNS II clocks are perfected for my work needs I do not have a life. I am going to bed at 3 AM and waking at 6 AM and commuting to Austin every weekend. Do not expect much from me, i.e., I do not have time for hour+ long TS meetings until probably the middle of July. At that time, I want to make a major push on getting the ACP and Linear experiments revisited after a year's work and analysis. I suggest we plan on some activity associated with that. The critical mass right now is in California and I have the approval to get some space out there for RF congregation that I need to close the loop on when the dust settles on some of these activities. I expect to attend a Suitsat2 meeting for a day in early July but there will be little else from me for a month. The SDX is working well in software. Howard is doing a great job. Lyle wants to begin work on the SDX hardware by fall. Marc Franco has his paper published and we can begin implementation of the VHF transmitter and the EER part of the SDX in earnest as soon as we have an exemplar from Marc or get his designs and recreate them. Next, we paid the huge freight to the State Department for our ITAR issues after we listened to Harold Price, our attorney's, etc. For those who are not U.S. citizens and members of this group, you will, as individuals or through sister societies, need to enter into Technical Assistance Agreements with us, even if you are Canadian, British, German, etc. (All the usual suspects). This is not as painful as it may seem since we are going to do the boiler plate but it must be done. Bob -- AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair "If you're going to be crazy, you have to get paid for it or else you're going to be locked up." Hunter S. Thompson

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TeamSpeak conference for 12 June 2007
by Jim Sanford 12 Jun '07

12 Jun '07

Team: For some reason, although I can edit the EaglePedia page of team speak conferences to include the agenda for tomorrow night, when I save the changes, they don't take. (Dave Hartzell, please help! Additional request for improvement sepcor.) It's time to resurrect the monthly TeamSpeak conferences. I know why we missed May, I don't remember missing April.. The conference will be tomorrow night, 12 June 2007, at 2100 EDT, 1800 PDT, and 0100 ZULU. Therefore, here's my proposed agenda for tomorrow night: 1. UHF RX update -- Juan Rivera 2. S2 RX update -- Bill Ress 3. AMSAT Symposium planning -- me 4. Work Breakdown Structure -- Gould Smith and me. 5. (If present) V-band TX, Marc Franco 6. (If present) SDX, N4HY 7. (If present) ACP, N2MJI/K3IO 8. Whatever ELSE you want to discuss. Thanks & 73, Jim wb4gcs(a)amsat.org

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Phased Array Prototyping -- help wanted
by Tom Clark, K3IO 12 Jun '07

12 Jun '07

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Concerning Jim Sanford!
by Tom Clark, K3IO 11 Jun '07

11 Jun '07

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2007 Symposium -- call for papers
by Jim Sanford 10 Jun '07

10 Jun '07

Team: The first call for papers for the 2007 AMSAT Symposium has gone out, the second will go out shortly. Here's how I see it: This is a BIG year for Eagle. We need to have much to say and demonstrate. I expect to demonstrate: U-RX S2-RX V-TX SDX IHU anything else that comes together. I expect to see presentations from each and every team lead. We need to show the membership what we're DOING and reap the benefits therefrom (hint, hint). Specifically, I think we should present papers on: Project management and status (I am willing to present 45 minutes; I'd much rather talk for 45 SECONDS outlining what YOU will present -- you're doing the work!) U-RX S2-RX IHU/CAN-Do! V-TX SDX The LAB (with LOTS of photos!) Structure redesign Power systems Antennas ACP Orbit analysis/prediction/control Propulsion requirements I'd like to see each of you submit an abstract in the next week or so, and then a paper. If you can't be present to personally present the paper, let's get it published anyway, and give me the chance to find someone to present it for you. Matt, Phil, Bob: We REALLY need to publish something about the ACP. The last public pronouncement is the minutes of the San Diego meeting almost a year ago. Yet, the ACP is a (to some, THE) major Eagle payload. But all we've published is some musings on the phased array antennas. Matt, you talked about a "generic" digital package at Portland, it's time to at least articulate the things we're thinking about. Eagle should dominate the Symposium to the point that the ultimate arbiters of presentations say, "Enough!!" If you have questions or need guidance, please contact me. Again, it is very important that the Eagle team have a large presence at Symposium this year. Some would say it's not necessary, since we're on EaglePedia. I disagree: decades ago, in a Public Speaking course, I learned that, "You've got to tell them, and tell them, and tell them again.) days ago, in a recruiting/retention seminar, a marketing expert told me that you've got to tell them SEVEN, I say again, SEVEN, times. EaglePedia is only one. So, let's think about what we're doing, what we're planning to do, and what we've accomplished. Then let's write it down. By the way, much of what I have in mind here is information you need to send me anyway for my update to the Board of Directors, so this really isn't that hard. Please prepare something. Submit abstracts to Dan Schultz, and copy to me so I know what to expect. Thanks & 73, Jim wb4gcs(a)amsat.org

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New 70 cm Receiver Test Results
by Juan Rivera 10 Jun '07

10 Jun '07

Re: 70 cm Prototype Receiver Testing John, and group, I set up my shop this evening to take a look at the microphonic issue that I had noticed before Dayton. I decided to use my new SDR-IQ software defined radio instead of my HP 8566B spectrum analyzer. The SDR-IQ has a lower noise floor, is quiet, and doesn't heat up my shack. Of course it tops out at 30 MHz and the 8566B goes up to 22 GHz. But for this application all I needed was something to look at the IF output at 10.7 MHz. Before I got to the microphonics I noticed spurs and phase noise that I had not previously seen with the 8566B - a classic case of going to drain the swamp and then ending up fighting alligators... I've posted screen shots and test details on EaglePedia's 70 cm receiver page. Click here <http://www.juanr.com/pages/hobbies/ham_radio/Eagle/Testing_Resumed.htm> for a link to that top level page. Then go down to the Project Status area and open up Troubleshooting <http://www.juanr.com/pages/hobbies/ham_radio/Eagle/Testing_Resumed.htm> Resumes. I wouldn't get discouraged. This is why we built the prototype in the first place - to find all the little flaws that need attention. More to follow in a few days... P.S. I add new material to the end of these logs so if you've already read the earlier posting just scroll down to the new material at the end. I always try to note the date and time I last modified the log at the top so you can see if there is anything new since your last visit. 73, Juan WA6HTP

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Re: New 70 cm Receiver Test Results
by Juan Rivera 08 Jun '07

08 Jun '07

Re: 70 cm Prototype Receiver Testing 08 June, 07 John, and group, The spurs I mentioned yesterday are caused by the power supply. Follow the links below for details... 73, Juan WA6HTP Click --> <http://www.juanr.com/pages/hobbies/ham_radio/Eagle/Testing_Resumed.htm> ere's 70 cm Receiver testing to read latest log P.S. I add new material to the end of these logs so if you've already read the earlier posting just scroll down to the new material at the end. I always try to note the date and time I last modified the log at the top so you can see if there is anything new since your last visit.

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Re: Broadband amplifier paper for symposium
by Daniel Schultz 06 Jun '07

06 Jun '07

> Here is an abstract of a paper submitted to the October symposium, I thought > it might be of interest to the group. > > Dan Schultz N8FGV

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Florida AMSAT net is looking for guest speakers
by Andrew Glasbrenner 04 Jun '07

04 Jun '07

If you have an AMSAT topic that is near and dear to your heart, we would be happy to provide a forum for you to tell our members about it. The Florida AMSAT net is actively seeking guest speakers for our Thursday night net. Our net covers about 1/2 of the area of Florida or better, and has up to 40 participants per net, including international checkins via echolink. We have a very reliable echolink connection, so you may present your topic from your hi-speed internet linked computer, or possibly use a local rf system to connect. We are also working on providing reverse autopatch capabilities. We have had one previous guest speaker, Bob WB4APR, immediately after the deployment of RAFT and ANDE. That net was talked about for months, and we would like to begin a tradition of interesting and relevant guest speakers. Please contact myself or any of the three other net controls listed in the cc: if you'd like to participate as a guest speaker. 73, Drew KO4MA

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Hello from WA6HTP
by Juan Rivera 01 Jun '07

01 Jun '07

Hello to the wider AMSAT/Eagle community, This is my first posting to the AMSAT/Eagle mailer. For those of you who don't know me, I'm the team leader for the 70 cm Receiver construction and testing group. Out team on the west coast is constructing and testing the first prototype receiver. It recently returned from its trip to the Dayton Hamvention. While it was gone I took the opportunity to catch my breath and I purchased an inexpensive software defined radio. It's called the SDR-IQ and I've written a brief report which you can access via my web site <http://www.juanr.com/> or via the Eagle <http://www.amsat.org/amsat-new/eagle/EaglePedia/index.php/U-Band_Receiver> Receiver page. On the Eagle Receiver page you'll find quite a few logs detailing our progress so far. The SDR-IQ write up is at the top of the list. 73, Juan WA6HTP

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Internet connectivity restored
by Jim Sanford 30 May '07

30 May '07

All: My broadband connectivity to the main computer has been restored, thanks in large part to randy, N3ZK, who helped me thru Microsoft's obtuse, convoluted internet connection sharing. While suboptimal for many reasons, it works, and I have restored broadband connectivity to the main computer. This means my low profile of the last 2 weeks is over. Thanks Randy. 73 to all, Jim wb4gcs(a)amsat.org

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Test msg for Juan & Don, all others delete without reading
by Jim Sanford 30 May '07

30 May '07

Juan & DOn: Testing your Eagle connectivity. Pls confirm receipt. Thanks & 73, Jim wb4gcs(a)amsat.org

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Various issues
by wb4gcs＠wb4gcs.org 30 May '07

30 May '07

Team: Much has happened over the last couple of weeks that I need to address. First some background: I apologize for being low profile lately, and allowing things to fester which should have been resolved sooner. Unfortunately, I've been dealing with some personal issues (consider, Non Maskable Interrupt) and with my 84 year old Pearl Harbor veteran father who has been with us enroute the new home enroute the nursing home. I'm sorry to have neglected Eagle, but had to deal with the immediate issues. There have been some important discussions, on and off list, which have simultaneously been productive and not necessarily contributory. I should have reacted sooner, but couldn't. I hereby strive to get things back in the box. I'd like to restate some "groundrules", history, and current status as I know it, if you will: Eagle is an open project. All we do is visible to the AMSAT membership, and all we do is open to their question. NEVER FORGET: "Its nice to see all this new technology, but what are you clowns doing to make sure the thing JUST WORKS?" Communications within the team should be open and technical, not personal. Messages which say or imply, "you idiot, that will never work because. . .." are just not helpful. We must have a clear and visible demarcation between open discussion and things that must be formal, such as decisions, requirements, etc. For my part, when I authorize an expenditure, or publish a decision, I will ALWAYS do so in e-writing in an unambiguous way. Things such as requirements changes, will be discussed, peer-reviewed, and formally announced. Requirements are always open to question and modification, ESPECIALLY as designers and constructors learn new things. The recent work on the U-band receiver prototype have been MOST illuminating -- and well documented on EaglePedia. I believe the work by John, Juan, and the Project Oscar team sets an example, matched only by Bdale and Stephen with regard to the CAN-Do! widgets. We still need to document requirements for some pieces of the satellite. To help with this, I have some friends looking for some freeware requirements management tools. (This is different than Vision and MSProject, which we're already using, I'm talking about tracing the history of requirements generation, and tracking requirements-to-test traceability.) You guys in industry -- I'm open to suggestion. Team leads: IF we don't have good requirements for your "piece", you know who you are, we ought to be developing them, so that we can proceed with prototyping and testing -- against requirements. There have been some questions and different understandings on how we will command Eagle. Bob McGwier and I sorted thru the various thoughts a few days ago. The primary command will be L-band, direct into the IHU, as was discussed in the Orlando meeting. The always-on U-band receiver will also be a command receiver -- thru the SDX, since the IHU can only accommodate a single I/Q pair. I particularly like this approach, because it minimizes (not eliminates) opportunities for a single failure to take out all command capability. (TBD on whether or not the S2 ACP uplink can also be used for command. It was discussed as a possibility in San Diego, but has not been decided, to my knowledge.) This is consistent with the discussions at Orlando. Another lesson learned from the U-RX prototype effort is that receivers must recover from power interruptions autonomously, without IHU intervention. This realization has some of us ready to go to crystal LOs; Bill Ress has articulated some other options. Look for a discussion on this topic after we have results from the U-RX ATP and revise the design for flight. There will be another peer review. There have been some questions and discussion regarding temperature range the payload modules can expect to see. There's some discussion of this in the notes from the Orlando meeting, but this is an area where we need to document some requirements. To help, Bob McGwier is doing a historical search on what AMSAT has designed to in the past. His results will be published. Related to the above, Juan Rivera has raised some very good issues regarding temperature and effects of differential coefficients of expansion. Thermal design is becoming more challenging as LSI devices generate more heat in smaller areas, raising local heat fluxes much higher than we've ever worked with before. Ancient parts have become unobtanium, so we have to figure out how to deal with this -- the thermal folks have their work cut out for them, but industry is doing it. Aggravating the above, today's SMD components are smaller and more brittle, making it possible for temperature issues to physically break things. Juan has posted some interesting information on "things" that can break SMD stuff. (If you haven't yet checked out his construction notes on EaglePedia, you're missing a REAL treat. Bdale said in Pittsburgh, "Our legacy may very well be in our documentation," and Juan is providing the documentation in a huge way.) Related to thermal issues, there has been some discussion regarding use of machined enclosures, rather than the sheet metal which is our current design. Bob Davis, mechanical team lead, will evaluate and provide a recommendation -- look for this discussion. I've seen some discussions regarding all the "wasted space" as a result of the larger structure, driven by our power and antenna needs. Please, let's not go down the path of tossing in the kitchen sink to fill the volume. We have discussed one or two TSFR spaces, and this should continue, but payloads beyond what the BOD approved in SFO should be viewed skeptically. All right, that's what I have to say by way of "catching up." Given Murphy's law, somebody is going to be pissed about something herein -- please don't be. Let's not get emotional about technical subjects. We're all working toward the same end, and I'm trying to bring some structure to our efforts. In my experience, a large team like us periodically needs to step back and review the bidding, and that's the purpose of this email. Goals: Again, I apologize for not making Dayton, and not having the working things that Juan, Project Oscar, and Bill Ress worked so hard to deliver to me. Given the "frantic" nature of Dayton, I'm told that I make a bigger deal out of this than it was, because few would have the opportunity to really hang around and study. Symposium in Pittsburgh will be different. We MUST have some working things to show, and I want to be able to announce early -- as an inducement to the membership to come on down. I believe this is achievable -- U-RX, V-TX, SDX, IHU, possibly a power demonstration. For info, our host in Pittsburgh, the Wireless Association of South Hills, has in the last 18 months, raised quite a bit of money and constructed a trailer-mounted tilt-over, crank up tower, for use at Field Day and in emergencies. This will be at Symposium, and will have whatever antennas on it we like. I'd REALLY love to have a working transponder hooked up to it, so that we can demonstrate, in the local area, not just at the hotel, what Eagle will be like. (We can also work satellites overhead as demos.) Personal note: Again,I apologize for my low profile lately. I'm getting back in the saddle, as I get hammered from all sides to, "slow down". I briefly considered reducing my time/efforts on Eagle, but quickly realized that would be MORE stressful than what I'm doing. Working with this team of brilliant intellect has been enjoyable and rewarding, matched by only a very few things in my entire life. I thank you all for that. As time goes on, we're all going to get busier, so we need to step up recruiting efforts, and I'll be asking some key people to help me on discrete tasks. Thank you all for indulging my pontifications. Let's press ahead. Thanks & very 73, Jim wb4gcs(a)amsat.org

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Re: Status update and request for action
by Robert McGwier 29 May '07

29 May '07

Juan: And you would be absolutely right. Since John developed the original requirements document in concert with engineering management to meet the requirements we wanted (PAVE PAWS immunization, support SDX, etc.) aren't we glad that we have followed this procedure? We will again. Let me know if you receive two copies of this email. If you did, you are a member of the group. A CAVEAT: YOU MUST POST FROM THE ACCOUNT ON WHICH YOU RECEIVE THIS EMAIL. It has to have some identifier to go by. Bob Juan Rivera wrote: > John, > > Its no reflection on you but I still feel that it is fundamentallky wrong for the designers and builders to create the requirements document. It's an issue of customer vs. supplier. The requirements should be supplied by the customer (AMSAT management). Then the folks that are tasked with designing and building the device should generate a plan to meet the requirements. > > I'd post this on the AMSAT/Eagle newsgroup if I was on that list but I'm not. > > 73, Juan > > > On 5/26/07, *John B. Stephensen* <kd6ozh(a)comcast.net <mailto:kd6ozh@comcast.net>> wrote: > > I think that the next step in the development of the 70 cm receiver > needs to > be updating the requirements document and getting it approved by > those who > will interface to the receiver. It was written over a year ago and > things > have changed. In my mind, there are several issues that need to be > resolved: > > 1) Storing the frequency setting. > > 2) Phase noise. > > 3) Frequency reference failure detection and switchover. > > 4) Thermal environment. > > 5) Waiving the hardware telecommand decoding requirement. > > I'm in the process of updating the document and should done done in > the next > few days. > > 73, > > John > KD6OZH > > -- AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair "If you're going to be crazy, you have to get paid for it or else you're going to be locked up." Hunter S. Thompson

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Re: Status update and request for action
by Robert McGwier 29 May '07

29 May '07

And you would be absolutely right. Since John developed the requirements document in concert with engineering management to meet the requirements we wanted (PAVE PAWS immunization, support SDX, etc.) aren't we glad that we have followed this procedure? We will again. Let me know if you receive two copies of this email. If you did, you are a member of the group. A CAVEAT: YOU MUST POST FROM THE ACCOUNT ON WHICH YOU RECEIVE THIS EMAIL. It has to have some identifier to go by. Bob Juan Rivera wrote: > John, > > Its no reflection on you but I still feel that it is fundamentallky > wrong for the designers and builders to create the requirements > document. It's an issue of customer vs. supplier. The requirements > should be supplied by the customer (AMSAT management). Then the folks > that are tasked with designing and building the device should generate a > plan to meet the requirements. > > I'd post this on the AMSAT/Eagle newsgroup if I was on that list but I'm > not. > > 73, Juan > > > On 5/26/07, *John B. Stephensen* <kd6ozh(a)comcast.net > <mailto:kd6ozh@comcast.net>> wrote: > > I think that the next step in the development of the 70 cm receiver > needs to > be updating the requirements document and getting it approved by > those who > will interface to the receiver. It was written over a year ago and > things > have changed. In my mind, there are several issues that need to be > resolved: > > 1) Storing the frequency setting. > > 2) Phase noise. > > 3) Frequency reference failure detection and switchover. > > 4) Thermal environment. > > 5) Waiving the hardware telecommand decoding requirement. > > I'm in the process of updating the document and should done done in > the next > few days. > > 73, > > John > KD6OZH > > -- AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair "If you're going to be crazy, you have to get paid for it or else you're going to be locked up." Hunter S. Thompson

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Pictures Of U Rx Housing?
by Bill Ress 28 May '07

28 May '07

Sounds like we'll be soon embarking on a "frank" discussion regarding the concerns Juan brought up during his teams build of the prototype U Rx. Good!! Have any pictures been posted of what the completed "Dayton" unit looked like? Juan presented some in process pixs but I don't recall seeing the completed unit. Regards...Bill - N6GHz

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Policy
by Robert McGwier 28 May '07

28 May '07

I agree with Tom's sentiment and I gave the old "Bob can be a jerk" stomping to private conversation's on Eagle technical matters off list. It ends NOW. We discuss project technical matters here, from the beginning to the end. Personnel issues are to be dealt with privately with/by the project manager and NEVER on this list. There are many who are on this list who have lots of experience in building these packages for spacecraft. We need the benefit of all of their experience. Bob -- AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair "If you're going to be crazy, you have to get paid for it or else you're going to be locked up." Hunter S. Thompson

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Re: We need to step back and reorganize
by Tom Clark, K3IO 28 May '07

28 May '07

Robert McGwier wrote: > There are several who have said their posts to the Eagle list are > bouncing. For those who are having trouble with posting to the Eagle > list (such as Juan), please tell Jim Sanford so he can correct the > problem. He is the eagle list (eagle(a)amsat.org) administrator. > The problem is that this off-line list now has has ~18 addressees. Adding eagle(a)amsat.org (now making ~19 addressees) causes a "rules" violation that requires manual intervention by a moderator (I presume = Paul, KB5MU). The obvious fix is to quit mailing to the long list! Tom

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Re: We need to step back and reorganize
by Bill Ress 28 May '07

28 May '07

Hi Bob, Good to hear you weighing in. Just on the subject of posting to Eagle, we need to understand why it keeps "bouncing" posts made to Eagle. Both Tom and I have tried and received bounces saying there are to many recipients. So there is NO, again NO overt attempt to restrict posts, just an apparent posting glitch, which I'm trying to work around with this post by eliminating all recipients except you (and then including the Eagle address). We'll see how that works. So NO need for scolding from on high. No one has lost the desire to be open. We just ran into what I guess is a "posting format" issue. Looking forward to your revelation(s)...................... Regards...Bill - N6GHz Robert McGwier wrote: > Jim and I are reviewing the remarks but my first pass at this is to > review history before I review the current situation in detail. We > have had MANY spacecraft go in and out of eclipse. We have done > thermal design work for all of them, and that work has been first > class, and we have never EVER flown electronics where we allowed the > temperature to move outside of its usable range. The very suggestion > that we would is almost insulting. What I suggest is that we take a > deep breath and analyze the situation without resorting to the sky is > falling syndrome. > > > The receiver will operate within specifications and thermal stresses > will be mitigated. The points about mounting the circuit board and > the bending torques thermal stresses will reviewed. Any modifications > to the hardware will be okayed post haste. > > I want everyone to hold together here because I am going to hint at a > secret that I hope is about to be revealed. DO NOT SNATCH DEFEAT FROM > THE JAWS OF VICTORY. I believe we have extremely exciting > developments about to come upon us for a ride to orbit <as in a launch > contract>. Do not lose heart now. All programs for space undergo > changes as gotchas come up. This is no reason to be discouraged but > in my mind has always been a thrill because we have worked hard and > overcome them. The only place in my mind where our management > situation failed completely was on AO-40. It has never been > completely comfortable but it is simply the nature of activities like > this where almost everyone, if not everyone, is a volunteer. > > Last: WHY is this conversation not happening in the Eagle mailing > list? I object most strenuously because it is not consistent with our > promise to design in the public eye. We cannot start this by hiding > our work from other eagle team members who might be wondering if any > work is going on at all. I will listen to any good reasons before I > issue an irreversible order. We will have a small insurrection on our > hands when a few of the members who have not been privy to the > conversations (and who are potentially very large donors) find out > such as Phil Karn and Franklin Antonio. I have Franklin's assurance > we can build the ACP in Qualcomm labs with their having equipped it. I > will not have him angered by secrecy. This should not have been > allowed to continue. > > > 73's > Bob > N4HY > > > > Bill Ress wrote: >> Juan, (et al.,) >> >> It will be interesting to see the responses you get to your VERY >> appropriate post. Obviously you are wrestling with several very >> important issues. >> >> I hope your subject title "We need to step back and reorganize," is >> meant to apply not just to your 70CM Rx but to the whole Eagle program. >> >> I was going to add more of my few cents but I'll wait to see if and >> how upper management replys to your points. >> >> We should all ask ourselves: why have there been so many amateur >> satellite failures since AO-40? In the current batch of recently >> launched CubeSats, many are non or semi operational. I don't know why >> they failed once in orbit after working fine on the ground. Could it >> be that some of the issues Juan brings up caught those design teams >> in the butt? >> >> Hang in there Juan - we really need your great efforts, knowledge and >> frank and honest criticisms. I know you're just trying to help build >> a "reliable" satellite worthy of the many thousands of donor dollars >> that will go into Eagle. >> >> Regards...Bill - N6GHz >> >> >> Juan Rivera wrote: >>> Jim, >>> >>> I'm writing to you at 4:00 AM because I've been laying awake for the >>> past >>> three hours worrying about this receiver project. Let me go over a >>> few of >>> the surprises that we've encountered after the requirements were peer >>> reviewed and approved, my team was brought on board, the receiver was >>> designed, parts ordered, and construction started: >>> >>> 1) Power can be interrupted every three seconds and the receiver has to >>> store enough charge to survive those outages. >>> >>> 2) The receiver is not the telecommand uplink receiver. That >>> receiver isn't >>> even on UHF. It's on L-Band. >>> >>> 3) The lower temperature extreme it must survive is not -20C. It's >>> -70C. >>> >>> 4) The chassis it will be mounted in flexes. >>> >>> 5) It may or may not have to operate while subjected to PAVE PAWS >>> interference which is either impulse radar or chirping across the >>> entire >>> satellite UHF segment. >>> >>> 6) The receiver cannot depend on a boot from the HCU. It must be >>> autonomous. >>> >>> 7) The Can-do module power switch will be bypassed to provide >>> continuous >>> power to the receiver. No, wait! The receiver will be shut down during >>> eclipse and cold soaked to -70. Well, it's one of those two anyway. >>> >>> I'm sure I'm forgetting a few items, but you get the idea. >>> Obviously the >>> original requirements document was incomplete. In my opinion this >>> was a >>> result of the unstructured and informal approach that was used, and >>> the fact >>> that the RF designer, John, wrote it instead of a system engineer >>> looking at >>> the satellite as a whole. >>> >>> The receiver ATP peer review is another example. I know there are >>> problems >>> with that document. After all, I wrote it. Unfortunately I have not >>> received one single comment suggesting an improvement, even though >>> it has >>> been posted on Eaglepedia since last year. >>> >>> Now is the perfect time to create a structure that will avoid these >>> problems >>> from now on. It should start with a completely new receiver >>> requirements >>> document, an ICD (Interface Control Document), and an actual review >>> of the >>> ATP. >>> >>> The requirements document needs to have input from everyone that has >>> anything to do with the project - thermal, power, mechanical, >>> control, EMI, >>> etc. There should be a formal checklist to insure that no >>> functional group >>> is omitted from the process. >>> >>> There needs to be another checklist that spells out exactly what >>> needs to be >>> included in the specification. If the two lists are complete, and >>> adhered >>> to, then all future requirements should be complete as well. >>> >>> The requirements need to start by defining the RF environment that the >>> receiver is expected to operate in. I've seen email suggesting that >>> PAVE >>> PAWS is impulse radar. The addendum that is attached to the ATP >>> suggests >>> otherwise, but it could be wrong. The nature of the RF environment the >>> receiver will operate in needs to be defined clearly. The ATP >>> references >>> that addendum and has a test or two designed to characterize receiver >>> operation under the conditions that addendum and John's requirements >>> document outline. Are those assumptions incorrect? Does it really >>> matter >>> since this receiver is no longer the command uplink receiver? The >>> entire >>> design rests on assumptions that may or may not be accurate. All of >>> these >>> issues need to be addressed before John is turned on to begin the >>> revision >>> process. >>> >>> I also question the mechanical layout of the receiver. Having the >>> Can-do >>> module at right angles to the receiver makes no sense in terms of space >>> utilization. Perhaps it should be a daughter board that sits >>> parallel to >>> the main PCB. The DB15 also doesn't make any sense to me. I'm >>> sorry but >>> why use such a large connector? At the very least a 15-pin >>> connector could >>> be used that occupies a DB9 shell. That connector dictates having the >>> Can-do module vertical, which in turn forces the chassis to be much >>> higher >>> than it needs to be. The front panel space is also severely >>> restricted by >>> the Can-do PCB, leaving very little room for connectors associated >>> with the >>> main PCB. >>> >>> The case itself is flexible and that flex will be transferred to the >>> PCB and >>> from there to the SMD devices, many of which are very susceptible to >>> mechanical damage from board flex. Lastly, the entire rear third of >>> the >>> chassis is empty - another waste of space. I know I'm stepping on >>> toes but >>> I'd much prefer milled aluminum boxes to sheet metal. They wouldn't >>> necessarily be much heavier and would be much more rigid, providing >>> badly >>> needed stability to the PCBs. I fully expect to be shot down on >>> this but it >>> should be open to discussion while a new requirements document is >>> created. >>> Working with surface mount devices is completely different than the >>> through-hole PCBs of the past. These devices have special needs >>> that can >>> only be ignored at your peril. >>> >>> I don't mean this email to be a complaint because we've learned a >>> tremendous >>> amount in the process so far. I'm actually very excited about the >>> chance we >>> now have to really tighten up the requirements definition process >>> and take a >>> fresh look at this receiver. The lessons learned on this project >>> will make >>> life much easier for the next group. I'm convinced. >>> >>> 73, >>> >>> Juan >>> WA6HTP >>> >>> >>> >>> >> >> > >

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Re: We need to step back and reorganize
by Bill Ress 26 May '07

26 May '07

Bob, I hear what you say about machined housings and the concerns that Juan has about sheet metal. Personally I prefer a machined housing to help (not cure) many of the issues that Juan raises regarding CTEs. Consider this..... I have been using eMachineshop ( www.emachineshop.com) with great success and with very nice pricing for rather simple machined housings for my microwave widgets. I have a small prototype mill and lathe to build the first one and when I'm happy, the drawing is converted to their software, the quote is done online, you place your order and the parts come in the mail. So we don't need a team member with CNC capability. Since our housings are somewhat "universal", a "basic" housing can be machined (in quantity) with modifications tailored to the specific circuit variations required. Seems like we have to do that with the sheet metal housing anyway. Just a thought!! Regards...Bill...N6GHz Robert Davis wrote: > Juan, > You bring up things that should be discussed. I hope you're not as > frustrated as your email sounds. If you are, then I fear that our > communication shortcomings are worse than the technical problems you > refer to. > I can comment on a couple of your points. > > Here's the history of the module development as I heard it. From AO-40 > there was the desire for greater access to components on the PCBs, by > removing the side walls. As a reaction, Dick created a lightweight > module where the PCB mounts to the baseplate, then a cover is added. > This was his solution for the "requirement" he was given or at least > interpreted. > I absolutely recognize the problem of having a baseplate that can be > flexed or even bent, to which a geometrically sensitive circuit board > is screwed, and then this is contorted to fit a potentially imperfect > cover. It seems to me that machining a module (base & walls) would > contradict the requirement Dick had to begin with. It's also possible > that the requirement for greater access is just plain at odds with > SMDs. Maybe this can be improved with a thicker baseplate. This is > absolutely an open issue right now. > > The CAN-DO is another topic. You're right. You can trade internal area > for the connector face. I do regret that this was not a specific > conversation earlier, as you have the PCB area to do almost anything. > > As for the unused area inside the module, I personally have no > interest in pursuing module dimensions that react to the PCB > dimensions in both planform directions. We already have 3 module > variants where we vary one planform direction. I think this is enough. > The spacecraft module mounting real estate is not valuable enough to > make modules based on each PCB delivered. We've essentially bloated > the exterior of Eagle to generate more power, and the innards haven't > changed much. > > You also bring up machined chassis. On AO-40, AMSAT paid for *a lot* > of machining, because AMSAT has no specific CNC capabilities. > Volunteers offer what they have, and whatever volunteers we have this > year has entered into our decisions on what to make. And certainly > this is the case for machined modules versus bent sheetmetal. Using > jigs, it was seen as a good thing that modules could be replicated by > someone with perhaps fewer fabrication capabilities. The bent > sheetmetal chassis have alignment issues that in the 3 or 4 prototypes > we made, we were unable to demonstrate reliable tolerances. This > didn't bother me so much, as the alignment jigs for bending were built > during this process. You certainly imply here that sheetmetal modules > are not compatible with SMD PCBs. I hope that's not true, as then > that's a driving requirement for us mechanically. > > Anyway, there's my comments for the day. I suspect the issues you > bring up are major enough that we'll be addressing them for a while, > not simply a weekend of emailing. > > Best regards, > bob > Robert Davis > KF4KSS >

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Re: We need to step back and reorganize
by Tom Clark, K3IO 26 May '07

26 May '07

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Flex Radio gathering and presentation
by Robert McGwier 15 May '07

15 May '07

From John Basilotto, W5GI, at Flex: Subject: FlexRadio Systems Social and Presentation at Dayton Date: Saturday May 19 Time. 7:45 PM until 11:00 PM Place: University of Dayton, Kennedy Union, Barrett Dining Room ( 1st floor) Program: formal program starts at 8:15 PM. Presentation by Gerald Youngblood: SDR update and the FLEX-5000. Flexi Awards and prize drawing immediately afterwards. Complimentary soft drinks and pretzels. Program will be broadcast on Team Speak courtesy of Eric Ellison. Parking: all university parking lots can be used. See map at http://admission.udayton.edu/virtour/Campus_map_text.swf Directions from various points at Dayton http://www.udayton.edu/Visiting+UD/ Strip maps will be available at the FlexRadio booths 315-317. Please note this is the only presentation that Gerald will make during the Hamvention. Hope to see you there. -- AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair "If you're going to be crazy, you have to get paid for it or else you're going to be locked up." Hunter S. Thompson

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TeamSpeak conference tonight
by Jim Sanford 09 May '07

09 May '07

All: My apologies for not sending out an agenda sooner. To be honest, with all that's been going on here, and following the U-band RX work, it slipped my mind. Anybody who wants to show up at 2100 EDT, 1800 PDT, please do, and discuss whatever. I have a township planning commission meeting in 30 minutes and might be a few minutes late. I will check in as soon as I can, and will be prepared to discuss U-vand RX status. (I expect Juan will NOT be able to make it.) Another topic we could discuss would be Dayton. Finally, my verizon wireless connection has been incredibly cantankerous lately, so I may not make it at all, or may drop out. IF so, press on without me. Thanks & 73, Jijm wb4gcs(a)amsat.org

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1/2 Scale model at Space Day
by Robert McGwier 08 May '07

08 May '07

http://n4hy.smugmug.com/gallery/2819832/1/150794625#150796886 Those are Jansson's modules on top (with the other clutter). One is a standard module. The other is a cut away of a heat sink module. Bob -- AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair "If you're going to be crazy, you have to get paid for it or else you're going to be locked up." Hunter S. Thompson

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a stress break for the UHF receiver team... ;-)
by Bdale Garbee 07 May '07

07 May '07

http://www.xkcd.com/c227.html

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Travels
by Dick Jansson-rr 07 May '07

07 May '07

I will be on the road from 07 to 14 May and will not have ready access to the computer. If there is an immediate need for my services please call me on my cell: 407-810-3359. '73, Dick Jansson, KD1K <mailto:kd1k@amsat.org> kd1k(a)amsat.org <mailto:kd1k@arrl.net> kd1k(a)arrl.net ---------------------------

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Eagle model
by Robert McGwier 06 May '07

06 May '07

Yesterday at Space Day at the Air and Space Museum (D.C.) , Bob Davis revealed the Eagle structure 1/2 scale model. I will put up pictures later to give everyone a look. It is a very nice look. I have neglected to post my remarks on Dick Jansson's module designs. I have had a regular module and a cut away of the heat sink module. This is very fine work. My final remarks on the work will await Bob Davis and Jim Sanford and I looking at this together. But at this time, I see no reason at this time for us not to accept these modules and to thank Dick for his fine work. Bob Davis has the modules now. Next, we are doing more detailed work on the energy requirements of the spacecraft. We have very short periods of eclipses and while the angled arrays do a great job of mitigating off pointing angle, NOTHING can mitigate no sun at all! Given the amount of energy storage required to live through these eclipses, it is my OPINION that we are going to have to compromise on the periods of eclipse and TURN SOMETHING OFF. The amount of solar panel and battery storage required to keep everything alive through these eclipses, upon more detailed study, seems exhorbitant in terms of cost, weight, etc. Lou, Bob Davis, and I have discussed this and Lou and Bob both have very nice study tools. We need to write up a report on this for everyone to take into account. Juan Rivera and company have made great progress on the Stephensen 70cm RX recently. They are really doing a fantastic job. More will follow from them but it is good news. We will be doing dynamics testing, noise testing, etc. soon! 73's Bob N4HY -- AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair "If you're going to be crazy, you have to get paid for it or else you're going to be locked up." Hunter S. Thompson

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FWD: Eagle Update - Discussion of Plastic versus Military parts]
by Jim Sanford 30 Apr '07

30 Apr '07

All: Info. A little history on our off-and-on discussion about what kind of parts to fly. I have responded regarding his volunteering. 73, Jim wb4gcs(a)amsat.org -------- Original Message -------- Subject: Eagle Update - Discussion of Plastic versus Military parts Date: Mon, 30 Apr 2007 19:17:39 -0400 From: Daniel Kekez <va3kkz(a)amsat.org> To: wb4gcs(a)amsat.org Hi Jim, I read your recent Eagle Update in the AMSAT journal, and I found it interesting that you were having the Plastic versus Military parts discussion. I work at the Space Flight Lab at the University of Toronto, and we were trained by AMSAT almost a decade ago on the Microspace way. And part of that has been the careful selection of plastic parts in conjunction with intelligent designs. This combination has proved to be quite successful on the MOST microsatellite. On the other hand, I've also wondered about the suitability of COTS components for a HEO mission like Eagle which will pass through the radiation belts twice per orbit. So I'm quite curious to hear the details. I am wondering if the discussion you describe took place on a mailing list or some other forum to which I could subscribe. Now, since there is no such thing as a free lunch :), I have to ask what work I should contribute to get "in the loop". I don't have a lot of free time, given the demands of my job, but I could be of use in the immediate with digital electronics or software type of work. Anyway, please let me know. 73, -Daniel, VA3KKZ

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Another idea on phased array configuration
by Tom Clark, K3IO 29 Apr '07

29 Apr '07

7 22

Module Heat Sink
by Dick Jansson-rr 27 Apr '07

27 Apr '07

I have posted in the Eaglepedia>Eagle>Mechanical the specialized E05 50 & E16 10 drawings for the U Band receiver thermal control methods using localized heat sinks to cool the several high power density areas of the module PCB by conduction to the module base plate. These drawings are an indication of the methods that may need to be applied to other modules of the Eagle mission. Shortly I plan to post a note on this effort with the indications and methods applied so as to assist others in the program. with possibly similar needs. The door is open for inquiries. Dick Jansson, KD1K kd1k(a)amsat.org kd1k(a)arrl.net ---------------------------

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[Fwd: [CubeSat] Presentations online]
by Tom Clark, K3IO 23 Apr '07

23 Apr '07

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Failure analysis
by Jim Sanford 16 Apr '07

16 Apr '07

Team: I have updated the "view from the bridge" page with a link to NASA's preliminary report on the Mars Global Surveyor loss. Good read, some lessons for us. Thanks 7 73, Jim wb4gcs(a)amsat.org

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Dayton presentation
by Jim Sanford 11 Apr '07

11 Apr '07

All: I need to draft my Dayton presentation. I need input. I'm well plugged in to what the UHF receiver folks are doing (need photos). I have an idea of what's going on with the lab in MD (need photos). I desperately need info on power system experiements and progress, ACP progress, propulsion system progress, structure/thermal progress, V-band TX progress and SDX progress. Photsos would be a PLUS! I'm aware of sensor/GNC plans, would like an update on progress. I have a bunch of travel coming up for the Day Job, so will be a bit less accessible, tho will have time in hotel rooms to quietly work AMSAT things. I need your updates, photos, and other informations _/*SOONEST*/_. Thanks & 73, Jim wb4gcs(a)amsat.org

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Major Eagle events
by Jim Sanford 11 Apr '07

11 Apr '07

All: I send this separate note to advise you of some major developments with Eagle. Many of you are already aware of them, but in case I missed someone, I send this separate update. Two nights ago, I authorized expenditure of funds for purchase of components and construction of four prototypes of the UHF receiver designed by John Stephenson, KD6OZH. The boards will be distributed as follows: one to Juan Rivera, WA6HTP, for Acceptance Testing followed by limited vacuum and thermal testing one to be demonstrated at Dayton one to the SDX folks for their development one to be put through the ATP either here by me, or wherever anyone else wants to evaluate. This will then become available as needed for demonstrations or SDX development Events leading to this decision: Design by John and Peer review Development of ATP by Juan and peer review Assembly of a procurement, construction, and test team of Project Oscar members under Juan's leadership PCBoard layout by John. Peer review of schematic to board correlation in progress Development of costed Bill of Materials (BOM) by the Project Oscar team. This was a LOT of work, and actually resulted in some tweaks to design and component selection Peer review of the BOM in progress I have authorized $4100 for this effort. A small fraction of this cost includes consumables for surface mount construction and some assembly tools which will become AMSAT property and will be used again. AMSAT costs were reduced by a significant amount of "scrounging." I submitted some of this information for publication in ANS, but don't yet know if I was ahead of the deadline or not.. If I was late, I hope it will appear next week. This seems to me a huge step. We have completed one design cycle on one component and are now about to transition, for that one component, from the concept exploration/definition phase into construction of hardware. Prototype hardware, yes, but we will soon have some real test results and something real to show. The short list above belies a whole lot of work by a whole lot of folks, alll of whom I thank. Many of you participated in the earlier reviews of John's design and Juan's ATP. The near-frantic effort over the last few weeks by John and the Project Oscar folks (many of whom I'm just getting to know through various emails and echolink conferences) has been intense. As we progress with procurement and construction, I will receive and share progress updates as major milestones are met. The documents mentioned above are not all on EaglePedia yet, but will be. In particular, one unexpected fallout of the recent efforts is a BOM which may be a good template for other teams to use. It certainly made it easy for me to see and understand, "how many, how much?" Thank you all. Very 73, Jim wb4gcs(a)amsat.org

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TeamSpeak tonight
by Jim Sanford 10 Apr '07

10 Apr '07

Team: I had no opportunity last week, nor last night, to even THINK about an agenda. Might be informative to discuss the UHF receiver goings on. In case anyone wants to get on and just chat, I'll be there at 9pm eastern, 6pm pacific. Thanks & 73, Jim wb4gcs(a)amsat.org

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Re: Eagle Microwave Antenna Arrays -- mechanical concepts
by Tom Clark, K3IO 02 Apr '07

02 Apr '07

9 37

Urgent need for peer review
by Jim Sanford 01 Apr '07

01 Apr '07

Team: Juan rivera needs someone to peer review the correlation between UHF receiver schematic and the about-to-be ordered PCB layout. All info is available as .pdf so no fancy software etc. is required. Just a couple of hours to do some checking before we commit to production. Those who have been working on it are too close to it and need assistance from an independent observer.. If you can helpout, please contact Juan directly. juan-rivera(a)sbcglobal.net Thanks & 73, Jim wb4gcs(a)amsat.org

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Personal planning
by Jim Sanford 27 Mar '07

27 Mar '07

All: For your information, I provide some information regarding my status and forthcoming availability. My day job is getting busier. As a result of a bunch of things, I'm now the manager of what we'll call "shipboard automation." This means I have tentacles in all hardware, OS infrastructure, and custom applications being developed for the shipboard areas I care about. There are many things going on, but not necessarily well. Part of my mission is to herd the cats, set some priorities, and get some stuff done -- enough churn. I'll be attending "targeted selection" training for the next 2 days. TS is an interviewing technique, and there is a need for my assistance in interviewing candidates. Yeah, I know, there are millions, and it's not different from what I've done before, but training is training. I will be out of pocket the next two days, but briefly available in the evenings. (Obvious conclusion: I would welcome resumes from engineers seeking employment in the Pittsburgh area.) Starting Sunday (1 Apr), I'll be at Bechtel Project Management training for a week. I'm very excited about this -- Bechtel routinely does things that very few organizations in the world can do, on time, in budget, and without getting anybody hurt. This tremendou educational opportunity has been in the works for over a year. I'll have the laptop with me and access to email, but it will be after long days and several hours of homework each night. So, I'll be reachable, but in a limited/delayed way. This is a good thing, I'm SURE I'll get things out of this which will help me help Eagle. Bottom line: Don't stop sending me anything, just recognize that my responses may be delayed. We are within hours of authorizing construction of UHF receiver prototypes -- that work will be my highest AMSAT priority. Thanks & 73, Jim wb4gcs(a)amsat.org

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New Microwave IPA
by Tom Clark, K3IO 27 Mar '07

27 Mar '07

MIMIX has just announced some 2 stage moderate power (+20dBM 1dB compression, 23 dB gain, 4-21 GHz) Intermediate Power Amps that look interesting. They talk in terms of small 3x3 QFN SMT footprints. See http://www.mimixbroadband.com/PR/PR_022607.html for press release info. Anyone know anything about these parts? 73, Tom

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Power bus voltage
by John B. Stephensen 24 Mar '07

24 Mar '07

My current understanding of the DC power bus is that it is driven by banls of 4 Lithium-ion cells. These normally provide 2.7-3.6 V per cell but have 4.2V across them during charging at the end of the charging cycle. This would mean that the DC power bus in Eagle is 10.8-16.8 VDC. I don't see this documented in EagePedia. Is this correct? 73, John KD6OZH

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TeamSpeak conference for Tuesday 13 Feb
by Jim Sanford 23 Mar '07

23 Mar '07

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

5 4

High Efficiency Linear Amplifiers
by Tom Clark, K3IO 21 Mar '07

21 Mar '07

A message sent to the SoftRock40 news group led to an interesting discovery. There is an interesting 4-part series in the journal "High Frequency Electronics" that is a tutorial on various techniques to achieve high efficiency power amplifiers. The article mentions the Doherty technique from the 1930's which was the progenitor of Meinzer's HELAPS. To fetch the series, surf to http://www.rfcafe.com/references/magazine_articles/magazine_articles_2003.h… which leads to the 4-part article "RF & Microwave Power Amplifier & Transmitter Technologies". 73, Tom

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