- Eagle (INACTIVE) - mailman.amsat.org

Proposed 70 cm Receiver plan - Let's get this project going!
by Juan Rivera 10 Aug '07

10 Aug '07

All, The 70 cm Receiver has been stuck in a rut for too long. Now that I've completed my Symposium presentation I'd like to get it back on the tracks and moving forward again. Here's the way I see it: Passband Ripple - we want to understand this problem before proceeding with the next upgrade revision so we don't end up with another prototype that still has excessive ripple. John will design a new PCB that will act as a test fixture for the 199 MHz 1st IF string. Parts will be distributed to John, Bill Ress and to me. We will all work this problem in parallel. The PCB will also contain test fixtures for any other portions of the receiver that we want to characterize independently of the receiver. The various fixtures can be cut apart once the PCB is fabricated. I'd suggest that the proposed analog replacement 10 MHz reference be included. I'll run that in my temperature chamber. CAN-Do Module - No one has volunteered to work the power supply issue so I'll do it. It's my belief that the existing step-down converter is running at a much lower efficiency that anyone realizes. I'll test this theory and report back. It appears to be a generic characteristic of this type of converter that the efficiency drops off towards zero at very low output currents. As I've discussed in my logs, this one is only putting out 11 milliamps. This could also explain the motorboating that I have observed. So far I have not found any other switching step-down converter that is optimized for this low output current. This problem needs to be resolved now since it impacts the design of the enclosure. If we go to an analog regulator the CAN-Do conducted and radiated EMI problem will be completely eliminated. If we stay with a switching step-down converter then we may either need to move to a two-compartment enclosure or vacate the front third of the existing enclosure to escape the CAN-Do radiated EMI. The Enclosure - I put forth a recommended enclosure requirement calling for a worst case PCB flex of 0.0084" in any one-inch segment. No one has made an argument against this. I do not believe that the current sheet metal enclosure with attached self-clinching standoff mounts and three separate heat sinks can meet this proposed requirement over the proposed temperature range which extends down to -60*C. With the current design that attaches the CAN-Do module to the main PCB via the 40-pin header and then fixes the CAN-Do module to the front panel, there is no room for any flexing or twisting between the base plate and front panel since those induced stresses will be transferred directly to the solder joints on the 40-pin header. The sheet metal vs. milled enclosure questions needs to be resolved. Low temperature Operation - The minimum operating temperature of the SAW filters is -35*C and the minimum storage temperature is -40*. For the IC's the minimum operating temperature is -40*C and the minimum storage temperature is -65*C. These temperatures are not just guesses on the part of the manufacturer. They are a function of the difference in thermal coefficient of expansion between the various internal parts of the devices. Operation below the minimum operating temperature will cause premature failures to develop in short order. The worst case scenario would be to power up the Receiver after is had cold soaked to -60*C. The silicone would heat up very quickly and begin to expand. The thermoplastic case material would lag behind and expand at a different rate causing large internal stresses. I have not seen a final word on the minimum temperature that the Receiver will see in orbit. If it really is -60*C then I propose that a space-rated thermal switch in placed in series with the DC power to prevent activation below -40*. Even this thermal switch proposal side-steps the SAW filters which cannot withstand -60*C. The proposed work around of splitting the receiver into two sections adds complexity which reduces reliability. A way needs to be found to keep the receiver from dropping below -40*. External EMI from the primary power source - The next revision of the Receiver needs to include EMI filtering and possible shielding to deal with radiated and conducted EMI from all sources. These sources need to be identified and characterized so that the Receiver can be designed properly. It makes no sense to press on with the next revision upgrade until this is sorted out. Receiver Requirements vs. ATP - The ATP contains tests for which there are no requirements. We need to harmonize these two documents and do a new peer review for both. Let's get these items resolved!! 73, Juan - WA6HTP

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updates
by Jim Sanford 08 Aug '07

08 Aug '07

Team: A few weeks back, I requested updates for the Journal article, due now. I've received info from Juan Rivera, Bill Ress, Bdale Garbee, Marc Franco, and Bob Davis. Everybody else, please send me something before 1800 9 August, when I will start writing. This is the last Journal before Symposium, so it is our chance to provide reasons for members to come. Thanks 7 73, Jim wb4gcs(a)amsat.org

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Passband Ripple - Latest Modifications and Test Results
by Juan Rivera 07 Aug '07

07 Aug '07

John, Per your request I have modified the input coupling to the 2nd Mixer as follows: * Remove C37 * Replace L15 and L16 with 16 ohm resistors * Install 0.27 µH inductors from pins 2 and 3 of U8 to ground I then retested the IF passband ripple by sweeping a 1 MHz span centered on 10.7 MHz. The output level was reduced by 3 dB but there was no change in the ripple. Click HERE <http://www.juanr.com/pages/hobbies/ham_radio/Eagle/passband_ripple.htm> to view my log. I think we need to look outside of that coupling area since weve pretty much replaced every component. Lets replace both SAW filters next. What do you think? 73, Juan

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Receiver Spec vs. ATP, a few Suggestions and a Question or Two
by Juan Rivera 06 Aug '07

06 Aug '07

John, I took a few minutes to look over your new specs and compare them against the Acceptance Test Procedure. I've got a number of tests in the ATP for which there are no specs: * Image rejection * Internally generated spurs * Local oscillator leakage * Input and Output VSWR Items that need to be addressed that aren't in either document: * EMI conducted susceptibility * EMI radiated susceptibility * Short and long-term frequency stability I also take issue with the -60C minimum power-down temperature. I think this is unrealistic just from a CTE mismatch perspective. The reliability of anything subjected to that wide a temperature spread is going to suffer. A way must be found to raise that temperature. I have a few thoughts... The CAN-Do switching step-down converter is only supplying 11 milliamps. If we take a slight efficiency hit we could just go to a simple linear regulator and completely eliminate the radiated and conducted EMI emission problem from CAN-do. That eases the EMI filtering and shielding requirements for every single payload. That seems like a good trade-off to me. Rather than worry about trying to conduct heat through a PCB why not just go to externally mounted regulators for the CAN-Do and the Receiver right on the case itself. We're not that pressed for space. That eases the heat sink and the associated thermal gap filler issues. EMI will still be an issue, but only for external sources instead of one that is inside the enclosure itself. That strikes me as a huge bonus. Why not design a single-sided PCB with the regulators hanging over the edge and the whole assembly, PCB and regulators, mounted directly to the enclosure. Stick it in with the CAN-Do module in a separate cell. Filter all the signal and power through the common bulkhead. I'm also curious as to why you are specifying two different types of SMA connectors. 73, Juan - WA6HTP

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This weekend at Central States VHF Society
by Tom Clark, K3IO 02 Aug '07

02 Aug '07

This year's CSVHFS meeting wound up tonite in San Antonio. Among the many AMSAT folks in attendance were W4MO, W7LB, W5IU, W3XO, N4HY, K5SDR, W5SXD, N6TX, KL7UW and K3IO. There were no satellite specific papers presented this year, but the world of DSP and SDR was very much present. K5SDR presented his new SDR5000 radio. KL7UW (with the SDR-IQ) and W5LUA (with the Softrock-40) reported on the use of SDR receivers for various VHF/UHF/Microwave tasks. AMSAT highlights of the meeting came at Saturday Night's banquet. K3IO accepted a financial contribution from CSVHFS for AMSAT. And then the crowning glory: Bob McGwier, N4HY was presented the 2007 John Chambers Memorial Award for technical achievement, recognizing his many SDR and AMSAT activities. Bob joins previous AMSAT Chambers Award recipients W0LER, W0PN, W3GEY & K3IO. Congratulations to Bob -- 73 de Tom, K3IO

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Journal update
by Jim Sanford 01 Aug '07

01 Aug '07

Gents: I need your input NOW. I have to write an article this week for submission.. Please tell me what you have done, what you are doing, and what you are going to do. I can speak from memory to U-rx., S2-Rx, and CAN-Do!. In need inputs from IHU, Power, structure, and lab. Thanks & 73, jim wb4gcs(a)amast.org

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Intelsat
by Robert McGwier 01 Aug '07

01 Aug '07

Yes, we are talking with Intelsat. They have told us there is no reason to keep this is a big secret. Just do not spread it around all over the place until we have our deal set. 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: N4HY wins prestigious award
by Robert McGwier 29 Jul '07

29 Jul '07

Thanks Dale, Tom, and others. I have had great partners in all of my work. I am grateful for all of the ideas, support, trust, complaints, advice etc. that have flown freely from the SDR,Flex groups, TAPR, ARRL, and of course, AMSAT. It has been amazing fun to try out new ideas here and to work with Frank, Eric, and many others on our joint endeavors. There are too many people in AMSAT to thank but one must be singled out. Tom Clark talked me into doing technical work in AMSAT when I was still in college and later talked me into doing the DSP project with TAPR and AMSAT. That advice and encouragement had a tremendous impact on my life, defining its trajectory almost completely. My close relationship with Tom has gone on for over 25 years. Tom often does not seem to see that of all his contributions, the most important of all by far is the impact he has had on others through his friendship, mentoring, and leadership. In my mind, it is the one of the most accomplished lives in amateur radio and beyond if you completely subtract all of his technical work. Tom talked me into joining Central States who gave me the award. My wife and I love it so much we go every year not unlike most of its members. Dale, your friend was the runner up in the big CSVHFS operating award again with an eye toward going for first. I know you are proud of that friendship. I do not covet awards and I certainly don't seek them but the John Chambers award is one I am extremely proud to have as all of my engineering mentors in amateur radio have received it including, but not limited to, Tom and Jan King. This was a complete shock. 73's Bob Dale Boresz wrote: > Congratulations on the award Bob - and thanks for your continuing work > to advance the state of the art of radio communications. > > Great times for amateur radio. > > Dale > WA8SRA > -- 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 -- 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: This weekend at Central States VHF Society
by wb4gcs＠wb4gcs.org 29 Jul '07

29 Jul '07

CONGRATULATIONS BOB!!!!!!! Very 73, Jim wb4gcs(a)amsat.org This year's CSVHFS meeting wound up tonite in San Antonio. Among the many AMSAT folks in attendance were W4MO, W7LB, W5IU, W3XO, N4HY, K5SDR, W5SXD, N6TX, KL7UW and K3IO. There were no satellite specific papers presented this year, but the world of DSP and SDR was very much present. K5SDR presented his new SDR5000 radio. KL7UW (with the SDR-IQ) and W5LUA (with the Softrock-40) reported on the use of SDR receivers for various VHF/UHF/Microwave tasks. AMSAT highlights of the meeting came at Saturday Night's banquet. K3IO accepted a financial contribution from CSVHFS for AMSAT. And then the crowning glory: Bob McGwier, N4HY was presented the 2007 John Chambers Memorial Award for technical achievement, recognizing his many SDR and AMSAT activities. Bob joins previous AMSAT Chambers Award recipients W0LER, W0PN, W3GEY & K3IO. Congratulations to Bob -- 73 de Tom, K3IO _______________________________________________ Via the Eagle mailing list courtesy of AMSAT-NA Eagle(a)amsat.org http://amsat.org/mailman/listinfo/eagle

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CAN-Do 3-second Glitches
by Juan Rivera 28 Jul '07

28 Jul '07

Stephen, I've mentioned this to you before and you've been kind enough to try to explain it to me several times, but I wanted to document these CAN-Do three-second glitches for posterity. After you look over my log and listen to the recording please feel free to add to my log. Just send me your comments and I'll include them. Here's the link --> http://www.juanr.com/pages/hobbies/ham_radio/Eagle/3-Second_Glitches.htm 73, Juan

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DC Input Test
by Juan Rivera 28 Jul '07

28 Jul '07

John, I'm in the process of reconciling your requirements document with the ATP. The first test in the ATP is a receiver power supply test. Requirement Actual Result Minimum voltage with no loss of signal level 10.8 10.35V 312.1 mA Pass Minimum voltage with 1 dB loss of signal No spec 10.14 N/A Maximum voltage 16.8 16.8V 230.7 mA Pass Juan

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[Fwd: HFSS Training, Burlington MA, August 2-3]
by Tom Clark, K3IO 26 Jul '07

26 Jul '07

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Status update
by Jim Sanford 25 Jul '07

25 Jul '07

Team: It's time for me to draft the next Journal article. Please send me your update by Wed, 1 August. If you have no progress to report, please send me that. (And let me know what's coming in the near future.) Thanks & 73, Jim wb4gcs(a)amsat.org

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70 cm Passband at -1 dB and -60 dB
by Juan Rivera 24 Jul '07

24 Jul '07

All, I re-ran the -1 dB passband test of the 70 cm receiver for my presentation. Here's another look at a 500 kHz span at 0.5 dB/Div: Here's a look at the -60 dB passband with a 2 MHz span and 5 dB/div. I increased the input Level to get the skirts out of the noise. It's 1.248 MHz wide at -60 dBc. Juan - WA6HTP

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A new opportunity (Phase 4 lite?)
by Robert McGwier 23 Jul '07

23 Jul '07

In the last few weeks we have been presented with a new opportunity to launch RF platforms into space. This note will necessarily be cautious because we do not wish to do or say anything that will throw a monkey wrench into the works. More specific details than are given here will come from one voice, and that is from Rick. This is a major development. One which will refocus some of the energy of the organization should it come to pass. That said, no one in management has proposed we stop Eagle and Jim Sanford will remain its project manager irrespective of what goes forward on the new project because we are still looking for rides for it. The following is adapted from Rick's note to the board of directors, with comments from me (and edits). We are being asked to propose that we ride on someone else's satellite with our RF gear and antennas. The primary is not a small satellite. It will go to geosynchronous orbit. There are MULTIPLE rides being discussed but we have to get our act together for round one. The planned lifetime of the large satellite is over a decade and they have a track record of exceeding it. At the beginning of life it produces 1 kw of excess power and we are trying to ask for at least 1/3 of that because at the end of life, after years of solar degradation, that is what the primary expects it to produce as excess power. They do station keeping to maintain their subsatellite point. They provide the ride. Thus, we do not need a motor, fuel tanks, hydrogen bottles, propellant flow assemblies, or liquid ignition units. They provide the electricity, thus we do not need solar cells or a battery. We will not need an attitude control system at all or even attitude sensors except for "gee whiz" like cameras or experiments. They could easily provide us about as much space and mass as the Eagle would have consumed, BUT WE DO NOT NEED IT. Rick suggested to them that we would probably need as much antenna space as we have proposed for Eagle, and they did not blink. Mechanical constraints (moment of inertia ratios) allowing for a motor are completely out of the picture. We will be rigidly mounted to their frame and they do the work. They will be asked to provide some thermal control for our RF modules, which will sit on the Nadir pointing side of their spacecraft, which is 3 axis stabilized, and will of course be subjected to hours in the sun and hours in the dark. A careful thermal design is required. We will never need to point another antenna on the ground after the very first time should their payload behave. We will not need to despin a phased array at 3 rpm. WE WILL need a phased array but it will be adjusted in tiny increments on a daily basis at most. No more spin modulation unless there is some failure on their bird. We need our very high efficiency power amplifiers, both the proposed linear and hard limiting design to be, as much as possible, producers of RF and not heat. They are offering this opportunity because they have discovered that if a goodly portion of the heat that is dumped from their solar arrays at the beginning of life is consumed in RF, light, etc., it saves them a considerable number of resources. This was one clever study by an in house engineer. They have been given some basic technical information on our proposed payload. We, AMSAT, must get together now and provided them with real answers on our proposed payload in a formal written proposal, but they were given these rough estimates. We need to provide the follwing which includes but is not limited to: 1) Size & Mass [less than 50kg, probably closer to 20kg, no batteries, ] Antenna Configuration (space required) [they were told the same as Eagle, a 60cm per side hexagon or some equivalent] Frankly, it needs no symmetry at all. It can be completely determined by the needs of the antennas and the envelope restricting us. 2) Given that, there is no need for a very thick spacecraft since it has NOTHING in it but RF modules and computer(s). 3) Power requirements [they were told about 300 Watts] 4) Efficiency (how much power becomes heat) [we agreed to choose 0% to start thermal design] (sic, from Rick. I don't understand what needs to be calculated if we agree that we produce 300w of heat, then our body will quickly rise to a very high temperature and melt. I think they want to upper bound the thermal control needed for us. ;-) . ) 5) Need for some of their on board resources to be specified and more details follow after our study. 6) They must be told a REALISTIC schedule that we can meet. That will determine what launches will be available to us and where the multiple payloads will be placed. We do know their power bus is many times our planned voltage, and we need to decide if we or they build the power converter. This is pretty obvious because they don't want to power TWT's, etc. from 5 or 14V!!! If we do multiple payloads with them, as is currently proposed, they would consider providing a "LAN" for us to communicate between satellites to our payloads (think direct, bird to bird interlinking). If the design study says we will not impact them greatly, they can provide us this link. For Eagle, we have planned to use 3400-3410 MHz for Earth->Space and 5830-5850 MHz for Space->Earth. It may be necessary to switch these to be compatible with their transponders which are on nearly identical frequencies BUT IN THE OPPOSITE DIRECTION. We don't want to transmit near their receive frequencies. This raises a serious problem as Region 1 does not permit us to radiate signals from the satellite in the 3400-3410 MHz band if they can see it. So it is clear, I will need to call engineering meetings, and more than one, in the next couple of months. We are prepared to spend the money on these meetings and bet this will be pulled off. If it looks like we really will close this deal (as in signing an MOU) then we will definitely bet the farm on it. Right now, we probably should think we are basing the payloads initially on what has been thought of for Eagle and we need to rethink this because one thing should be crystal clear. THESE ARE NOT ADEQUATE. Think about what it will mean to have a very loud transmitter, either analog or digital, available 7/24/365.25 at the same spot in the sky. We do not have sufficient capacity in our current design, period. We would not want to do the SMS text messaging in the linear transponder, but would likely move it back to Microwave for example. This relieves the phase noise demands on the system for SMS (maybe not other considerations TBD). Also, the user antennas on the ground are fixed. We need some redesign starting from our basic payloads and then building them out to meet what capacity we think we can support but this will be the first time we have ever spent all of our power on the RF and very little on anything else! I hope you can see that we must be both bold and professional with a dash of caution. A dash only because the probable time schedule will not allow us to pontificate for half a decade. If we pull this off, there is very little doubt in my mind that this will change not only AMSAT, but amateur radio in general, and if we do our job well, in a big way. We must thank Lee McLamb profusely for finding out this opportunity was becoming available. Special circumstances allowed us, following his notice to us, to move VERY quickly to "go in at the top of the organization". That was done (MAN do I love low friends in high places and in this case, at the very top). More details will follow as the okay comes from Rick. Please refrain from speculation or much gossip. I know I would be heart broken if the wrong leak or wrong public statement caused us to lose this major opportunity. I will not be entertaining a thousand questions but I do want everyone to think about the redesign of the payloads carefully to support a geosynchronous bird. 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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DICK JANSSON -- I NEED YOUR DIRECT EMAIL ADDRESS
by Jim Sanford 19 Jul '07

19 Jul '07

For whatever reason, my address book only has the old ones . . . Thanks & 73, Jim wb4gcs(a)amsast.org

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Help Needed
by Juan Rivera 19 Jul '07

19 Jul '07

Hello All, I'm trying to arrive at a reliable method of measuring phase noise for the testing I'm doing on the 70 cm Eagle Receiver. I recently purchased an SDR-IQ software defined radio. It makes a great spectrum analyzer below 30 MHz, with a very low noise floor and great resolution. I took it to work to show to my coworkers and the lab manager liked it so much he purchased the big brother of this unit, the SDR-14, which I borrowed and brought back to my shop. I also sent my Agilent 8566B spectrum analyzer out for calibration so now I have three pieces of test equipment that I can use to measure the phase noise of the 70 cm Receiver. My problem is that I cant get any two of them to agree... Ive fed the same 10 MHz 0 dBm signal into each unit, recorded all of their settings and created the attached PDF file. As you will see, they all differ. If we look at the 120 Hz power supply sidebands you get the following: SDR-IQ: -102 dBm SDR-14: -93 dBm 8566B: -84 dBm The 8566B automatically calculates RMS noise levels normalized to a 1 Hz noise power bandwidth by correcting for the analyzers log amplifier and detector response and compensating for the resolution bandwidth setting. Its capable of accurately measuring noise levels down to 10 dB above the spectrum analyzers noise level (-131.6 dBm) and reading out in steps of ±0.1 dB. At a 150 Hz offset it measures -104.0 dBc/Hz. Looking at the two SDR units its hard to reconcile this measurement with either of them, or to reconcile any of the power supply sidebands. Both SDR units measure power levels in a very linear way. Ive confirmed their accuracy at the levels Im interested in around -90 dBm. Can anyone shed any light on this? No combination of FFT block size, span, RF or IF gain, or filter bandwidth can make any two of these devices agree on the noise floor or the amplitude of the power supply sidbands. 73, Juan WA6HTP A man with a watch will always know what time it is - a man with two watched can never be sure.

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Payload Adapters and excess launch margins
by Lee McLamb 18 Jul '07

18 Jul '07

As Bob mentioned I attended the NASA/NRO Rideshare conference again this year. I've just uploaded a file to Eaglepedia with one of the presentations which shows the current and some proposed secondary payload adapters presented by United Launch Aliance (ULA - the new Boeing & Lockheed-Martin partnership). Especially interesting is the 1000 and 1500 lb propellent margins for the AEHF and WGS missions on slide 11. While we won't be ready for their first flight, both of these are the beginning of a constellation build-up which means there will be multiple re-flights for each. Now I'm looking for an angle to get Eagle into an IPC for one of these missions. http://www.amsat.org/amsat-new/eagle/EaglePedia/uploads/a/aa/Keath_Karuntzo… 73, Lee-KU4OS

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Re: [Advisors] A new opportunity (Phase 4 lite?)
by RaySoifer＠cs.com 18 Jul '07

18 Jul '07

In a message dated 7/17/2007 2:53:03 PM Pacific Daylight Time, rwmcgwier(a)gmail.com writes: > This raises a serious problem as Region > 1 does not permit us to radiate signals from the satellite in the > 3400-3410 MHz band if they can see it. Bob et al, This might overstate the problem just a bit. The ITU RR allow any country to put any station on any frequency, as long as no harmful interference is caused to stations operating in accordance with the Table of Frequency Allocations. So, depending upon the orbital station(s), it may be possible for us to design an antenna whose footprint would result in a PFD low enough in the Region 1 land mass so as not to cause harmful interference there. One more design issue for the engineering team.... 73, Ray

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Source of 70 cm Microphoncs Found
by Juan Rivera 17 Jul '07

17 Jul '07

John, The microphonics is caused by C19, C27 and C28 (.047uF 25V) and C50 and C51 (.022uF 25V). I found the best way to isolate this is to inject a CW signal into the receiver, tune the signal in at the IF output using my TS-2000 in AM mode, and then listen to the audio output while lightly tapping each component one at a time. According to my research, barium titanate, the base ceramic material for most ceramic SMD capacitors is inherently microphonic. Juan

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2M High Efficiency PA
by Tom Clark, K3IO 14 Jul '07

14 Jul '07

In case you missed it, the following EAGLE item appears in today's AMSAT NEWS SERVICE (ANS) bulletins: > SB SAT @ AMSAT $ANS-196.04 > High Efficiency RF Linear Amplifier Design Proposed for Eagle > > AMSAT News Service Bulletin 196.04 > >From AMSAT HQ SILVER SPRING, MD. > July 15, 2007 > To All RADIO AMATEURS > BID: $ANS-196.04 > > AMSAT members Allen Katz, K2UYH and Marc Franco, N2UO have > designed a VHF, high-efficiency, class-E, RF power amplifier > with a DC to RF efficiency of 86.8%. Their innovative > design is based on silicon carbide (SiC) metal-semiconductor > field effect transistors, or MESFETs. > > The design was presented in a paper at the IEEE International > Microwave Symposium in Hawaii. It is now available on-line: > http://www.cree.com/products/wireless_docs.htm titled > "Class-E Silicon Carbide VHF Power Amplifier" (June 5, 2007) > > The final amplifier efficiency was measured at around 86 to 88% > with this number holding quite well at almost any drain voltage > or output power. This type of amplifier is under consideration > for the envelope elimination and restoration linear amplifier > planned for the AMSAT Eagle satellite. > > [ANS thanks Marc, N2UO for the above information] > > /EX > Marc has promised to have a presentation with more details on this work for the October AGM in Pittsburgh. (BTW -- Marc & Patty are expecting their first 2nd harmonic)

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EMI Control & PCB Analysis - Aug. 22, Boston
by Tom Clark, K3IO 14 Jul '07

14 Jul '07

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Phase Noise Calibration
by Juan Rivera 13 Jul '07

13 Jul '07

All, I've written up my efforts to understand the SDR-IQ and to use it to measure phase noise on the 70 cm Receiver. You can read it HERE <http://www.juanr.com/pages/hobbies/ham_radio/Eagle/Phase_Noise_Calibration. htm> . 73, Juan - WA6HTP

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P3E SDX Design Levels take 2
by Howard Long 11 Jul '07

11 Jul '07

Folks Sorry I will try again with some formatting. Following the Teamspeak meeting, the pertinent levels for P3E: V Tx Phase +10dBm @ 145.895MHz into 50 ohm; V Tx Envelope 2Vp-p into 1kOhm baseband; U/V AGC I/O: 2V full gain, 5V full compression (output capable of ~2.5mA drive); U band IF in -15dBm @ 10.7MHz into 50 ohm; L band IF in -15dBm @ 10.7MHz into 50 ohm; S band IF out -15dBm @ 10.7MHz into 50 ohm. 73, Howard G6LVB

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Re: 10 MHz Phase Noise
by Juan Rivera 11 Jul '07

11 Jul '07

Bill, I'm sending you my preliminary phase noise results. As you recall, I constructed a battery-powered 10 MHz oscillator by grabbing a junked reference oscillator from an old HP signal generator and mounting it in a box with two 9-volt batteries, a switch, and a BNC. That allowed me to bring it into work and use the Agilent ES5500 Phase Noise Measurement System on it. Then I brought it home as my poor-man's phase noise source. Here's the test results on the oscillator and the first look at the SDR-IQ: Phase noise of the battery-powered oscillator Here's the same oscillator captured with the $400 SDR-IQ. The SDR-IQ drifts in relation to the device under test so the signal average is artificially low. It's really at 0db on the scale. With the IF and RF gain set to their lowest settings I think this lines up pretty well until the level drops down to the SDR-IQ baseline noise level at about the 100 kHz point. The 120 Hz bump has to be coupling from the PC via the USB port where it gets its power. I was able to rid the SDR-14 of that by tossing the wall wart and using a lab bench supply. For now I'll just ignore this one. What do you think? Juan -----Original Message----- From: Bill Ress [mailto:bill@hsmicrowave.com] Sent: Tuesday, July 10, 2007 7:27 PM To: Juan Rivera Subject: 10 MHz Phase Noise Hi Juan, Really sorry you couldn't transmit this evening. I always enjoy your keen comments. Thanks for the 10 MHz phase noise data. What is the model number for the HP oscillator? It's probably a version of the one I use. Now - - - - I'm really interested in what you read on your SDR. On the 8566B you'll just be looking at its internal LO's phase noise floor but it will be very interesting to see what your SDR phase noise floor is. Your test results will be the key data point in my decision to buy one. Again - much thanks for you fine work. Regards...Bill - N6GHz

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P3E SDX Design Levels
by Howard Long 11 Jul '07

11 Jul '07

Folks Following the Teamspeak meeting, the pertinent levels for P3E: V Tx Phase +10dBm @ 145.895MHz into 50 ohm V Tx Envelope 2Vp-p into 1kOhm baseband U/V AGC I/O: 2V full gain, 5V full compression (output capable of ~2.5mA drive) U band IF in -15dBm @ 10.7MHz into 50 ohm L band IF in -15dBm @ 10.7MHz into 50 ohm S band IF out -15dBm @ 10.7MHz into 50 ohm 73, Howard G6LVB

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Re: P3E SDX Design Levels
by Howard Long 10 Jul '07

10 Jul '07

Sorry I will attempt a re-format... Following the Teamspeak meeting, the pertinent levels for P3E: V Tx Phase +10dBm @ 145.895MHz into 50 ohm V Tx Envelope 2Vp-p into 1kOhm baseband U/V AGC I/O: 2V full gain, 5V full compression (output capable of ~2.5mA drive) U band IF in -15dBm @ 10.7MHz into 50 ohm L band IF in -15dBm @ 10.7MHz into 50 ohm S band IF out -15dBm @ 10.7MHz into 50 ohm Howard -----Original Message----- From: Howard Long [mailto:eagle@howardlong.com] Sent: 11 July 2007 02:59 To: 'AMSAT Eagle' Subject: P3E SDX Design Levels Folks Following the Teamspeak meeting, the pertinent levels for P3E: V Tx Phase +10dBm @ 145.895MHz into 50 ohm V Tx Envelope 2Vp-p into 1kOhm baseband U/V AGC I/O: 2V full gain, 5V full compression (output capable of ~2.5mA drive) U band IF in -15dBm @ 10.7MHz into 50 ohm L band IF in -15dBm @ 10.7MHz into 50 ohm S band IF out -15dBm @ 10.7MHz into 50 ohm 73, Howard G6LVB

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Password change part 2
by Robert McGwier 10 Jul '07

10 Jul '07

I have changed the password back to Eagle. It is now consistent with the Eaglepedia web page. Sorry for the confusion. 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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Can't Log Into Conference
by Bill Ress 10 Jul '07

10 Jul '07

Hi Guys, For some reason "Eagle" doesn't log me in. Did the channel password change?? Regards...Bill - N6GHz

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TeamSpeak Password Changed
by Tom Clark, K3IO 10 Jul '07

10 Jul '07

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TS channel recreated
by Robert McGwier 10 Jul '07

10 Jul '07

I have no idea what happened. I recreated it AMSAT Engineering, password eagle1 and since it is fortunate I cannot remember what day of the week it is, I will see you folks tonight. 73's 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
by Dick-rr 09 Jul '07

09 Jul '07

With the bringing of the new computer on line, I discover that I do not have the information needed to bring up the Teamspeak connection. Can someone help me today so that I can be available tonight? Dick, KD1K

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TeamSpeak conference for 10 July
by Jim Sanford 09 Jul '07

09 Jul '07

Team: Reminder, our next conference is next Tuesday at 2100 EDT, 1800 PDT, and 0100Z. I will write the agenda (much) later tonight. If you have inputs, pls get to me, or feel free to modify mine, once I load it on EaglePedia. Thanks & 73, Jim wb4gcs(a)amsat.org

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First Temperature Run on the 70cm Receiver
by Juan Rivera 06 Jul '07

06 Jul '07

Greeting! I hope you are all having a great 4th of July! And as Jim says, please give a kind thought to the folks over in the Mid East. The temperature over there in the summer gets up to about 135 in the sun. It's a miserable environment just trying to walk from one place to another in a tee shirt. I can't imagine how anyone can grunt 40 or 50 pounds of equipment and have to worry about getting blown up. Believe me. They all earn their pay! Early this morning I started setting up for the first temperature run on the prototype 70cm Eagle Receiver. Unfortunately I believe that the master oscillator has got to go. I'll verify my suspicion this evening when the temperature in the shack drops back down to survivable levels... Please take a look and my report by clicking HERE <http://www.juanr.com/pages/hobbies/ham_radio/Eagle/Temperature_Run.htm> and look for the three audio wav files towards the end. 73, Juan - WA6HTP

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70cm Receiver Temperature Run in External Reference Mode.
by Juan Rivera 05 Jul '07

05 Jul '07

All, I ran a Temperature Run on the 70cm Receiver in External Reference Mode. Click HERE <http://www.juanr.com/pages/hobbies/ham_radio/Eagle/Temperature_Run.htm> for details... 73, Juan

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70 cm Frequency Stability Tests Results
by Juan Rivera 04 Jul '07

04 Jul '07

All, I should have gone to work today but I ended up working on the 70 cm Receiver all day instead. Today marks a milestone for me -- my first use of audio files. You'll find two in my write up if you click HERE <http://www.juanr.com/pages/hobbies/ham_radio/Eagle/Stability.htm> . I think they work much better than descriptions and graphs. Now you can hear what I'm talking about... Have a great 4th! I plan to do a temperature run on the receiver tomorrow to celebrate! Let's see what that internal oscillator does when it's not at room temperature! P.S. to OSCAR guys... If you have time come on over and help me run this test. I'll probably start early to beat the heat. If you've never been gassed by CO2 before, now is your chance! 73, Juan - WA6HTP

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TeamSpeak conference for Tuesday 10 July 2007
by Jim Sanford 04 Jul '07

04 Jul '07

All: For whatever reason, I'm unable to update EaglePedia (it ignores my changes), so here's the agenda as I see it. Feell free to suggest additons to me, I'll keep a running total and publish just prior to the meeting. Topics: 1. Symposium 2. Requirements documentation ' 3. WBS and schedule development 4. Status reports UHF RX S2 Rx 5, EMI Please add topics. Thanks & 73, Jim wb4gcs(a)amsat.org

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70 cm Receiver Frequency Stability and One More Glitch
by Juan Rivera 03 Jul '07

03 Jul '07

All, Here's a plot of frequency drift in the 70 cm Receiver - first on internal reference, then on external reference: The first part of the plot is with the receiver and the signal generator set to 435.500000 MHz on internal reference. You can see the slow steady drift upwards of about 15 Hz over a period of about 5 minutes. Then I reinitialized the receiver for the external reference. It locked right up and the output was exactly 10.700000 MHz where it stayed. The most important thing I noticed is not on this graph. With internal reference selected, but while feeding 10 MHz into the external reference input, (as it might be configured in flight) the two reference signals are beating together. It wasn't until I started listening to the output of the receiver by patching it into a distribution amplifier so I can feed my counter, the SDR-IQ, the TS-2000, and the HP 8566B all at once that I noticed it. The result is that the input signal is FM modulated by the beat between the two reference oscillators. I also noticed some unexplained jumps in frequency that I have not yet been able to capture. I'll dig into this again when I have more time. 73, Juan

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CAN-Do Causing RF Frequency Jumps in 70 cm Receiver
by Juan Rivera 03 Jul '07

03 Jul '07

John and CAN-Do Team, I was in the process of checking some configuration files in preparation for my hunt for the 10.7 MHz spur. I initialized the receiver on 435.500, internal reference, and set up the SDR-IQ to display the IF output signal. Then I clicked the heartbeat button on the Can-Do Net Controller and was about to load the initialization file for external reference. As soon as I clicked the heartbeat button the IF output started jumping. I think it's the three second jumps that I have seen before, but I thought those were caused by a momentary loss of DC input power. In this case the receiver power is coming directly from the bench supply. I killed the CAN-Do module power and the IF jumping stopped. As soon as I applied power to the CAN-Do module again, the jumping returned. The duration of the jumps is very short and I am unable to capture a carrier - either with the SDR-IQ or using my TS-2000. They sound like clicks over a wide frequency range. Since the next revision of the receiver will be autonomous, perhaps this won't be an issue for us, but it will for others so it should be understood and documented in my opinion. 73, Juan

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10.7 MHz Spur
by Juan Rivera 03 Jul '07

03 Jul '07

John, I found the source of the 10.7 MHz spur. It's being generated inside the receiver itself. This is the first spur I have found that is not caused by switching power supplies. The origin appears to be in the 10 MHz reference area. I turned off and unplugged the SDR-IQ and fed the IF output from the 70 cm Receiver to my TS-2000. The spur is still there. Next I connected the RF input to my sniffer loop and moved it around the PCB surface. I get the strongest signal near the long trace between the two Freq inputs to U4 and U9, the two phased-locked loops. 73, Juan

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70 cm Receiver Spur Source Found
by Juan Rivera 30 Jun '07

30 Jun '07

All, The source of the spurs in the 70 cm prototype receiver is the CAN-Do module. This is the receiver IF output as designed (powered from pins 39 and 40 of the CAN-Do Module) This is the receiver running off of a separate power source (bypassing the CAN-Do Module +13 volt output on pins 39 and 40) This is the same configuration as above, but with the CAN-Do module shut down >From the above it appears that: 1. The CAN-Do module is the source of all the spurs that I see 2. None of the spurs are being generated by the receiver's internal power supplies 3. Some, but not all, of the noise is entering the receiver via the switched +13 volt CAN-Do output on pins 39 and 40 4. The remainder of the noise could be entering the receiver on other CAN-Do pins, or being radiated to receiver components or traces in close proximity See my log for all the intermediate steps I took to reach these conclusions. Remaining RF issues: 1. Phase noise 2. Microphonics 73, Juan WA6HTP

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Mocule Connectors
by rjansson＠cfl.rr.com 30 Jun '07

30 Jun '07

John & Juan: Your EMI problems certainly do present considerable difficulties. Your suggestions of placing connectors on multiple faces of a module run counter to the whole module mounting plan for Eagle. The modules are mounted with only about 1.5mm clearance at the flanges and only about 16mm clearance on the sides. The "rear end" of the module is also difficult as there is just not that much space for cabling and connector access. Mechanical designers in the past have been raked over the coals for not providing sufficient connector access. The curren plan allows about 100mm (I don't have the drawings with me at the moment) of space between facing columns of modules for the cabling and connector access. This is a plan that is pretty basic to the whole wiring plan for Eagle, and it is a result of a lot of experience with P3D. While the basic module design for Eagle, unlike P3D, does not provide for the stacking of modules, a small CAN module placed on top of the URx, could be considered. Wiring to this sub-module would be by means of jumper leads from its connector face into the URx. I caution that there currently is not planned for much space above the rows of modules as the current spaceframe plan has the modules placed fairly closely under the solar panels. This concept is part of the need to keep the mass moment of inertia, Izz, high. This is NOT just a desirable feature, but a necessary, MUST need for the spin stability of the spacecraft. So any top-mounted sub-module would have to not be very thick. All of these issues arise from the practical considerations of the overall mission of the spacecraft. Unfortunately for the EMI and other "local" issues, we cannot design the spaceframe only for EMI, but must solve other mission requirements, too. I am not trying to be unmovable on the design if the URx, but I am trying to explain how we can have a successful mission. '73, Dick, KD1K

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Re: 70 cm Receiver IF Spurs - Problem Solved
by Juan Rivera 30 Jun '07

30 Jun '07

Chuck, I don't want to tear into the CAN-Do module. I feel like it is a loaner and not mine to modify. It would be interesting to disconnect the switch and the current monitor from the CAN-Do power input and move it to those user pins as you suggest. That might just work, but I also know they don't want to have multiple versions of the module floating around and this would be one. We also can't loose sight of the radiated noise from that inductor. I can see signs of EMI if it gets within 2 inches of the sensitive areas of the receiver. 73, Juan 73, Juan -----Original Message----- From: Chuck Green [mailto:greencl@mindspring.com] Sent: Sunday, June 17, 2007 9:18 AM To: juan-rivera(a)sbcglobal.net Subject: Re: [eagle] 70 cm Receiver IF Spurs - Problem Solved Hi Juan, I am impressed with your testing and analysis. I find it curious that you were unable to filter the power from the CAN-Do! . But switching noise is notorious for being difficult to filter. So maybe that is something to just forget. But in a total system (satellite) it may not be possible to forget. We may need to find a way to filter the power for sensitive modules even if not using power from the CAN-Do! ; in which case, such a filter may also filter the noise from the CAN-Do! . If your analysis is correct, and it certainly seems to be, then it would also seem possible to remove the switch from the CAN-Do! (not just bypass it) and rout your clean power source through the CAN-Do! current measurement circuit thus saving having to do this in the module. Great work! And thanks. Chuck Juan Rivera wrote: > Hi Chuck, > > Bad news I'm afraid. See my report for details... I've sent out a link to > the group. > > 73, > > Juan > > -----Original Message----- > From: Chuck Green [mailto:greencl@mindspring.com] > Sent: Saturday, June 16, 2007 8:57 AM > To: juan-rivera(a)sbcglobal.net > Cc: eagle(a)amsat.org; David Smith; Dave Black (Work); Dave Black (Home); > Samsonoff@Mac. Com; Juan.Rivera (Work) > Subject: Re: [eagle] 70 cm Receiver IF Spurs - Problem Solved > > Hi Juan, > > This is fantastic! > > Please try one more experiment. Pass the module current through the > current measuring circuit on the CAN-Do! while bypassing the switch > transistor (you could just short across the switch transistor) and see > if the problem reappears. > > If you end up having to use the user pins, you will need to add current > measuring circuitry to your module. While this is no big deal, its one > more thing you might not have to do. > > Chuck > > Juan Rivera wrote: > >> 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 >> >> ------------------------------------------------------------------------ >> >> _______________________________________________ >> Via the Eagle mailing list courtesy of AMSAT-NA >> Eagle(a)amsat.org >> http://amsat.org/mailman/listinfo/eagle >> >> > > > >

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IMD, Phase Noise, a New Spur, and EMI suggestions
by Juan Rivera 29 Jun '07

29 Jun '07

All, I've started a new log here <http://www.juanr.com/pages/hobbies/ham_radio/Eagle/IMD+Phase_Noise.htm> . I've repeated some preliminary phase noise tests using a simulated PAVE PAWS signal, along with a simulated Ham uplink signal. In the process of looking at those signals with the SDR-IQ I discovered another spur directly in the middle of the IF. I don't know the exact source but it is generated inside the receiver, and definitely not from the CAN-Do module. I've also come to one general conclusion that I would like to bring up for discussion... I believe all switching power supplies on Eagle should be running at frequencies as high as possible - around 1 MHz would be a good ball park. That would put most spurs outside the passband of the payloads, and make EMI filtering much easier. The 5 kHz CAN-Do switching power supply needs to be completely redesigned in my opinion. I believe that if it is not cleaned up the impact will be devastating, and the full scope will likely not be known until integration and test when it is too late to do anything about it. Having said all that, I also believe that we need to come up with EMI standards for everything on Eagle. Specifically we need: 1) A definition of the noise amplitude and spectral content to be expected from the Eagle power distribution point 2) A repeatable way to reproduce that noisy DC source in our labs for testing 3) A simple and effective way to test to the spec that we create I think the way to make this work is to create a noise source that consists of several representative switching power supplies that are intended to be flown on Eagle. The exact makeup of this test fixture would be specified in the EMI requirements. Then, all payloads would need to be designed to operate without impairment while powered by this noisy power source. The EMI requirement would also spell out exactly what constituted impairment. They also need to keep conducted noise leaving the payload down to some specified level. More on that in a minute... Here's a possible layout for a noise source: The one ohm resistors account for lead resistance and allow the three switching power supplies to all modulate the power bus, along with whatever conducted EMI comes back from the devise under test (your payload.) It would be easy to crank out three or four of these noise sources for distribution to groups that need them. That way everyone would be testing using the same conducted EMI. The gold standards for EMI are MIL-STD-461 and -462. They break EMI into four categories: * CS - Conducted Susceptibility (the 70 cm Receiver suffers from this) * RS - Radiated Susceptibility (the 70 cm Receiver suffers from this) * CE - Conducted Emissions (The CAN-Do Module is guilty of this) * RE - Radiated Emissions (The CAN-Do Module is guilty of this) This noise source would provide a way to test for compliance with our CS requirement. RS and RE can be dealt with by shielding. That leaves CE. We'd need a way to insure that noise coming out of a payload is within spec. We'd need another test fixture for this. I hope this stimulated some discussion. I'm eager to hear what you all think... 73, Juan - WA6HTP

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Symposium -- call for papers and misc Eagle issues
by Jim Sanford 27 Jun '07

27 Jun '07

Team: The second call for Symposium papers has been issued. As I said a while back, it is EXTREMELY important that Eagle have a lot to say and show at Symposium. Each TEAM should publish SOMETHING. I'd prefer team leads to present, but anyone on the team is fine with me. Or, if you have something to present, but can't make it, I'll do it, or get someone to. (This is a last resort, I want the presentations to be about what YOU are doing, not me. But I'd rather get the info out....) Please get your abstracts in to Dan NOW, so he can start planning. To that end, Tom Clark, has agreed to write, have peer reviewed and PUBLISH IN THE PROCEEDINGS the collected thoughts regarding phased array. (Thanks, Tom!!!) Other specifics: We have advertised the ACP as a key part of Eagle, the PRIMARY payload in the eyes of some. Yet, we've said little about it, since publishing the minutes of the San Diego meeting, which was held a year ago. Now is the time. We need to say a LOT about ACP: modulation schemes, digital protocols, multiplexing techniques, link budgets (in terms of how many watts I need on uplink, how big an antenna, and how good a preamp) etc. Yes, much of that can be gleaned from the SD meeting, but much is not yet defined. It's time to define it, and publish what is at least our current thinking. At least one ACP presentation needs to be for the general user, who is not a digital communications geek. We need to convince him what ACP will do, the benefits to HIM, and why he should buy the equipment when we make it available. Think of this one as a sales pitch. THIS IS IMPORTANT. Similarly, we need to publish some RESULTS from the power system experiments. Juan Rivera has agreed to something on all the efforts and results of the project Oscar team with the U-band RX. Juan, you and I have corresponded about which topic, I sent you suggestions, please choos and send in the abstract soonest. Writing the paper can come as it evolves. etc. etc. Guys, this is important, please make the commitment and take a few minutes to do the abstract. Dan needs it for planning, and Patti and Kevin need it for purposes of marketing Symposium. They are working hard on local educational connections, but that can only go so far without at least a list of content. Other: I apologize for my low profile lately. The last two weeks have been brutal at work, included a long trip to VA (spoke at a retirement, went to a wedding, and happened to be in town when my grandson was born 5 weeks early), a 27 hour power outage (now have a 5500 watt generator) and I did take time out for Field Day. I'm going to continue to be low profile, as I leave in an hour or so for a meeting in DC which will be gruelling. Back here Sunday, probably a day or so to recover, then back in the saddle. Despite all this, I have managed to provide answers Juan needed to continue working, and have corresponded with a couple of others. Thanks for all your efforts. We are a few short months from Symposium, please make the push.to publish. This is an opportunity we must fully exploit. Thanks & 73, Jim wb4gcs(a)amsta.org PS Grandson is fine, just tiny. He may even leave hospital this week. A few photos at www.wb4gcs.org jas

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70 cm baseband data from 70 cm Receiver
by Juan Rivera 21 Jun '07

21 Jun '07

All, I'm not trying to beat this to death but I want to make sure I fully understand what I'm looking at here... I spent some time this evening looking at the spectrum between the 10.7 MHz IF output and zero Hertz. I did this because I believe it may be a significant area of interest since the receiver will feed an analog to digital converter. The A/D converter is not a tuned stage so it will digitize baseband noise along with the IF signal. I've been told that the impact of noise in the baseband is to reduce the dynamic range in the digital domain. I'd appreciate an explanation since I am woefully ignorant in this area. I posted my results in the usual area. Just scroll down till you come to today's date. 73, Juan

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TeamSpeak security issue
by Alan Bloom 20 Jun '07

20 Jun '07

In an 8-hour period I have received five of these messages, which means that someone (always with the same IP address) has tried to guess my TeamSpeak password 25 times today. Anyone else seeing this? Alan -----Forwarded Message----- > From: TeamSpeak <forum(a)goteamspeak.com> > To: n1al(a)cds1.net > Subject: Account on TeamSpeak locked out > Date: Wed, 20 Jun 2007 03:44:48 +0000 > > > Dear alan_bloom, > > Your account on TeamSpeak has been locked because someone has > tried to log into the account with the wrong password more than > 5 times. You will be able to attempt to log in again in another > 15 minutes. > > The person trying to log into your account had the following > IP address: 70.86.138.114 > > Don't forget that the password is case sensitive. Forgotten your > password? Use the link below: > http://forum.goteamspeak.com/login.php?do=lostpw > > All the best, > TeamSpeak >

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CAN-Do noise abatement plan and questions
by Juan Rivera 19 Jun '07

19 Jun '07

Good morning Stephen, I do have a few questions. Thanks for asking! 1) What if the CAN-Do module suffers a failure that causes a current overload? Is it protected by a fuse? The next generation receiver should continue to function as long as it has power. An overload in either unit should not cause the other to fail. 2) Do you have any information of previous efforts to reduce CAN-Do noise by either shielding the module or replacing the inductor with a shielded version? 3) Do you have a shielded inductor that I could swap for the existing one if that proved necessary? 4) Have you designed a circuit that would allow temperature to be determined inside the receiver PCB itself, and not just on the CAN-Do module? This will be important, especially if the receiver is split into two separate enclosures. My plan is to desolder the CAN-Do module from the receiver PCB today and move the receiver PCB to the enclosure's rear set of mounts. This will put about 2-inches of space between the two. I'll make up two interconnecting cables - one just long enough to attach the two while in the case, and one that is a foot or two long, assuming that I can find the parts I need and don't have to solder the cable to the two units. I can use that long cable to try some troubleshooting. I'll use that CAN-Do's noisy inductor as the noise source and move it around over the receiver to see what affect it has. Perhaps I can find the area that is the most susceptible to noise that way. I think the next receiver could use the entire available board space to: 1) Put distance between the two modules 2) Further isolate the CAN-Do module with a shield if necessary 3) Add power supply input filtering and input current overload protection 4) Include CAN-Do data line filtering if that turns out to be necessary 5) Add a temperature sensor in the vicinity of the SAW filters, and another on the second PCB if it gets split into two sections One last question. How do I reduce the heartbeat timing below three seconds? I couldn't find any way to do that using the net controller. I'd like to confirm that the jump in frequency I see in the CAN-Do module's 5 kHz noise every three seconds goes away. 73, Juan _____ From: smmoraco(a)gmail.com [mailto:smmoraco@gmail.com] On Behalf Of Stephen Moraco Sent: Tuesday, June 12, 2007 7:21 PM To: Juan Rivera; Juan Rivera Cc: Jim Sanford; Bdale Garbee Subject: late to tonight's meeting Juan, Sorry I missed your presentation/discussion tonight. Any questions/issues for me re: CAN Do! ? Regards, Stephen -- kc0ftq(a)amsat.org

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CAN-Do Power Supply Instability
by Juan Rivera 19 Jun '07

19 Jun '07

All, I dug into the CAN-Do circuitry today. The CAN-Do module uses a Maxim max1836 switching down-converter. I found the following quote in the spec sheet, "Commonly, instability is caused by excessive noise on the feedback signal or ground due to poor layout or improper component selection. When seen, instability typically manifests itself as 'motorboating,' which is characterized by grouped switching pulses with large gaps and excessive low-frequency output ripple during no-load or light-load conditions." It reminded me of the waveform I captured earlier from CAN-Do inductor, L3. (See the waterfall display below.) Those are definitely grouped pulses with large gaps. Notice also that there is tremendous splatter over a large bandwidth that can just be seen as faint horizontal lines. I'd like to propose an alternative - Move the switching down-converters out to the power distribution and management area and feed DC to the payloads at an appropriate voltage so switching power supplies can be removed from all analog payloads. This would go a long way towards cleaning up what is shaping up to be a nasty situation. It's just not good design practice to bundle switching supplies with low-level analog signals. 73, Juan

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70 cm Eagle Receiver - Final Spur Report (at least for today...)
by Juan Rivera 18 Jun '07

18 Jun '07

All, I've completed my testing and analysis of the spurs that appeared in the IF output of the 70 cm Eagle Receiver prototype. I believe I know the source and the cause of all of them and how they can be eliminated or rendered harmless. Click HERE <http://www.juanr.com/pages/hobbies/ham_radio/Eagle/Spur_Suppression.htm> to read my report. 73, Juan WA6HTP

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