July 2007 - Eagle (INACTIVE) - mailman.amsat.org

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:[email protected]] 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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