December 2009 - AMSAT-BB - mailman.amsat.org

HD TV Noise
by H. Vordenbaum 29 Dec '09

29 Dec '09

Are there any ideas on which HD TV systems generate the least R.F. noise; Plasma vs. LCD vs LCD/LED ? I am interested since I am contemplating getting a fairly large screen HD TV in the near future and am wondering if it will raise the RF noise floor significantly around the house. The input would be from Time-Warner cable. There's already some noise birdies from various computers and internet in my scanners, etc. 73, Harvey K5HV

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SO-67 schedule
by Jan-Albert Koekemoer 29 Dec '09

29 Dec '09

Hello I've added the following to the revolving schedule. A disclaimer I've neglected to add before: we reserve the right to adapt the schedule without prior notice, but will try our best to stick to the published one as far as possible. EUROPE 01/01 09:44 01/01 11:19 02/01 07:50 02/01 09:24 02/01 10:58 03/01 07:30 03/01 09:03 03/01 10:36 04/01 08:43 05/01 08:22 06/01 09:35 07/01 09:15 exUSSR 30/12 05:42 31/12 05:20 31/12 06:50 01/01 05:00 02/01 03:06 02/01 04:39 02/01 06:16 03/01 05:55 04/01 04:00 05/01 05:14 05/01 06:46 USA 30/12 12:05 30/12 13:40 30/12 15:15 30/12 16:48 30/12 18:20 30/12 19:52 30/12 21:26 30/12 23:00 31/12 11:45 31/12 13:19 31/12 14:54 31/12 16:27 31/12 18:00 31/12 19:32 31/12 21:05 31/12 22:39 01/01 12:58 01/01 14:34 01/01 16:07 01/01 17:40 01/01 19:11 01/01 20:45 01/01 22:18 01/01 23:52 02/01 12:36 02/01 14:13 02/01 15:47 02/01 17:20 02/01 18:50 02/01 20:24 02/01 21:58 02/01 23:32 03/01 12:15 03/01 13:52 03/01 15:26 03/01 16:59 03/01 18:31 03/01 20:04 03/01 21:37 03/01 23:11 Regards Jan-Albert Koekemoer (ZR1JAK) E-mail Disclaimer http://www.sunspace.co.za/emaildisclaimer.htm

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AO-51
by graham mcphee 29 Dec '09

29 Dec '09

>From VK2AYE I had no trouble working ZL2BX on USB up and FM down at 1900utc, sig were very strong , for what it is worth 435.150 was 40 over 9 on TS2000 Graham VK2AYE

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HO68 Linear Transponder
by PY5LF 29 Dec '09

29 Dec '09

Hello Great contact last night with LU2DPW and LU5BOJ by HO68 , in SSB and CW, good signal from AOS to LOS! <http://www.youtube.com/watch?v=QaRRbFUrbh0> http://www.youtube.com/watch?v=QaRRbFUrbh0 <http://www.youtube.com/watch?v=r0J6EnzpUsM> http://www.youtube.com/watch?v=r0J6EnzpUsM Now , my SatPC32 are working fine. Thanks to China ! PY5LF LUCIANO FABRICIO CURITIBA-PR-BRAZIL GG54JM <http://www.qrz.com/db/py5lf> http://www.qrz.com/db/py5lf <http://www.falautomation.com.br/> www.falautomation.com.br

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another bleep sat
by Rocky Jones 29 Dec '09

29 Dec '09

http://www.spaceref.com/news/viewpr.html?pid=29916 _________________________________________________________________ Hotmail: Trusted email with Microsoft’s powerful SPAM protection. http://clk.atdmt.com/GBL/go/177141664/direct/01/

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XW-1 over South America
by PY2ZX 29 Dec '09

29 Dec '09

Hello Alan, ---- 28 Dec. 2009 HO-68 Linear Tansponder Turn On: 01:40...South America <<<<<<<<<<<< (...) 29 Dec. 2009 HO-68 Linear Tansponder Turn On: 01:20...South America <<<<<<<<<<<< (...) ---- Thanks for provided the XW-1 transponder to this part of South America. Here some recordings made in 29 Dec. 2009: http://www.youtube.com/watch?v=1auAZ1oh94o http://www.youtube.com/watch?v=uuDi0M7wZGI When is possible stay GG and GF fields on the HO-68 future operational planning. They are among the most dense in terms of amateur radio operators in South America but was not well covered on past schedulles. Anyway we are keep tuning even during beacon-only mode. These are some of the new graphics: http://www.archangelo.net/misc/sat/xw-1/graf/view.htm Flavio PY2ZX GG66nt

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Cosmonaut describes ARISS contact
by andy thomas 29 Dec '09

29 Dec '09

I thought you'd like to see the following blog entry: http://rt.com/About_Us/Blogs/orbital-log/2009-12-28.html 73 de andy g0sfj

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Re: Question about vacuum and power module for lineartransponder
by Michael Fletcher 29 Dec '09

29 Dec '09

>>> Hi AMSATs, >>> >>> After many work on my transponder design I decided to put some work in >>> extending my lab. >>> One of the things I liked to have is a vacuum test chamber, to test electronics >>> under vacuum conditions. >>> >>> I have looked around and I see all kind of classes of vacuum pumps, and their >>> equal increasing price. >>> My question is how deep the vacuum has to be to be able to do a valide test on >>> (space) electronics working under space vacuum conditions ? >>> >>> I also would like to know if anyone has experience in SSB mode with the new >>> power modules types from Mitsubishi. Like the RA60H1317M, which can give 60W >>> power on 2m with only 50mW input power. >>> I am looking for some PA behind my LE005-R2 transponder design, to get a small >>> sized high-power linear transponder. The transponder gives 200mW PEP, so the >>> 50mW is no problem at all.I just wonder how linear these Mitsubishi modules >>> are, when using in linear mode. >>> >>> In the datasheet it says that they 'may älso be used for linear mouldation", >>> which doesn't give many guarenty. Any experience with these modules in linear >>> (SSB) mode are welcome. >>> >>> 73 de PE1RAH, William Leijenaar >>> For my small mode-uv transponder design, please check: >>> www.leijenaarelectronics.nl >>> --- >> Hi William. >> >> A better solution would be to build a class AB linear from 2 suitable >> FETs. An even better solution but one requiring a lot of development >> would be to separate the modulation into phase and amplitude and then >> modulate the gate with phase and drain with amplitude. Efficiency >80% >> >> >> David > Hi David, G0MRF > > What you suggest is the HELAPS principle of Envelope Elimination and > Restoration that was used in all linear transponders from OSCAR-6 ,OSCAR-7 > OSCAR-10 and OSCAR-13 with an efficiency of about 85 % > > http://www.amsat-dl.org/dl/HELAPS_en.pdf > > The above is a complete description of the HELAPS principle written by > Dr. Karl Meinzer DJ4ZC with all functional schematic diagrams of the > linear transponder Mode-B on board of OSCAR-7 > > I hope it helps William PE1RAH > > 73" de > > i8CVS Domenico William, regarding vacuum, you need to be able to simulate the space environment as accurately as possible. This means you need to be able to create a high vacuum of the order of 1E-7 Torr or better. Going all the way to 1E-9 Torr and beyond would be great and the Big Guys even use ion getters to grab the last floating molecules captured to make the chamber resemble real space... AMSAT has experience e.g. with failure of a particular type of RF capacitor that fails _only_ in high vacuum, so the only way to segregate the good ones from the bad ones is (thermal) high vacuum. And when finding such a failure and having corrected it (you think), you _must_ take the time, patience and money to _redo_ the test to ensure your results. At the same time you need to slowly cycle through your planned temperature cycle, e.g. -40 ... +60 degrees C or whatever. Regarding HELAPS (or whatever other type of efficiency and linearity improving technology you want to use), this is the only way to go with a) limited power available, b) maximum RF output power needed and c) limited thermal dissipation possible in space. The old AO-07 is a favourite of mine. Here is the block diagram of the Mode B transponder (in Finnish) showing the components used for each stage: http://www.kolumbus.fi/michael.fletcher/ao_07b.gif For those interested, here is breadboard of an early 10 GHz HELAPS experiment: http://www.kolumbus.fi/michael.fletcher/X_band_HELAPS_2.jpg Back then, AMSAT-OH was not feeling confident in building a flightworthy 10 MHz SMPS HELAPS modulator, but since then I have been looking at a 12-polyphase modulator concept. The reliability issue here is a statistical one with the component count rising pretty rapidly. I just have personal dinosaur thing about wanting to experiment with this stuff in the analogue way ;-) 73, Michael, OH2AUE

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back on the birds after 15-year absence - want tips on antenna system
by William Hein 29 Dec '09

29 Dec '09

I was an active Satellite operator back in the AO-10, AO-13 and Radio Sputnik days (as AA6TT) and am just getting back on the birds after a near 15-year absence and am getting used to today's LEO sats. I completely missed AO-40. VERY surprised to learn AO-7 is QRV! I presently have an Arrow antenna on a tripod located indoors. Rig is a FT-847 with MacDoppler tracking software. I successfully heard the 70cm CW beacon from HO-68 earlier today so it's nice to know everything works. Will be attempting QSOs on future passes on this and other LEO birds. I will be building a more robust outdoor antenna system in a few months and want to make sure I am prepared for the satellites which may be launched in the next few years. Here is what I am thinking (overkill for LEO birds but I want to be ready to MEO & HEO sats): 10m Dipole V M2 2M-CP14 or Gulf Alpha 2M-8ELSat and SSB Electronic mast-mounted preamp U M2 436CP-30 or Gulf Alpha 70CM-16ELSat and SSB Electronic mast-mounted preamp Questions: (1) RHCP for the V and U Yagis? Any reason to have switchable polarity? (2) Anyone who has used both M2 and Gulf Alpha satellite antennas please comment on their relative merit.? I find M2 on-air performance to be very good however I have had problems with M2 feed-point failures. (3) Will next gen ham satellites have S-Band downlinks? (4) Will next gen ham satellites have L-Band uplinks and/or downlinks? (5) Other bands to be prepared for? (6) Are these the satellites currently available for 2-way QSOs? AO-7, AO-27, AO-51, SO-67 & HO-68. Did I miss any? (7) Any pattern to when AO-7 is in Mode A and Mode B? 73, Bill ----- William Hein, AA4XT mobile: +1 (615) 967-1226 email: Bill.AA4XT(a)Gmail.com Loc: EM65PS Web: AA4XT.com 6752 Owen Hill Road College Grove TN 37046-9122 USA

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AO-51 mode change and recommendation
by vk5alx＠amsat.org 29 Dec '09

29 Dec '09

Attempted to use this mode on 2 passes but was not successful. Several stations tried to work on the first pass over Australia (07:51 UTC 29 Dec) but audio was very weak and there was a lot of interference on the signal. Some stations had difficulty netting onto frequency, probably because they could not hear themselves clearly. On the second pass I could hear no other stations attempting to access and while the downlink signal was strong there were all manner of noises present and only once or twice could I actually hear my voice among the noises. I'm sure that last time AO-51 was in this mode it worked reasonably well. Will be interested to hear reports from other continents to see if the interference was specific to this region. 73 Alex / VK5ALX

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