September 2011 - AMSAT-BB - mailman.amsat.org

Re: Amplifier Suggestions?
by Tom Clark 22 Sep '11

22 Sep '11

James, KF6RFX asked: > We are looking for a UHF amplifier (430-440MHz) for a transceiver to go from > 10 mW to ~ 75W. Most of the amps were are funding require a much stronger > input power than we can do. Note, it's a transceiver, so we want to be able > to receive through the system as well. This is for half duplex satellite > communication using a USRP radio. > > Do you have any suggested amps? You might want to check with some of the "custom" amateur shops like Pure RF (http://www.purepowerrf.com/), Downeast Microwave (DEMI, http://www.downeastmicrowave.com/) or DB6NT (http://www.kuhne-electronic.de/en/home.html). In particular, DB6NT has 50mw in, ~50w out amplifier (http://www.kuhne-electronic.de/en/products/power-amplifiers/mku-pa-4047-60-…) that is close to what you ask for. You didn't mention price constraints. Any of the "conventional" amateur "bricks" are will probably set you back $500-$750. There are some commercial alternatives you might look at. In particular check out MiniCircuits; at the $2000 level, the LZY1+ (http://www.minicircuits.com/pdfs/LZY-1+.pdf) has 39+ db gain and will produce 50 w of RF on either 2M or 70cm. Their older ZHL-50W $1400 brick (http://www.minicircuits.com/pdfs/ZHL-50W-52.pdf) is also a good unit. On the MiniCircuits units, I'd strongly advise that you get it with their BIG heatsink/fan. You say you need fast half-duplex. I presume that the downlink will be on a different band (like 2M). If not, the selection of T/R transfer relays will not be easy, especially if you want to avoid zapping your LNA. Good luck & 73, Tom Clark, K3IO

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Amplifier Suggestions?
by James Cutler 22 Sep '11

22 Sep '11

Hello, We are looking for a UHF amplifier (430-440MHz) for a transceiver to go from 10 mW to ~ 75W. Most of the amps were are funding require a much stronger input power than we can do. Note, it's a transceiver, so we want to be able to receive through the system as well. This is for half duplex satellite communication using a USRP radio. Do you have any suggested amps? Thanks, --James, KF6RFX

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Arissat-1 Voice telemetry analysis from G0SFJ
by andy thomas 21 Sep '11

21 Sep '11

I have submitted for a tlm certificate my analysis of the voice telemetry from Arissat-1 on certain orbits in September (when I was present, hi). The dates of the receptions in September are in the analysis spreadsheet. The MET is decreasing, I think this is because the satellite comes out of eclipse and swithches on nearer the observation, as the orbit is precessing I think the analysis shows that as the MET decreases, the IHU temperature decreases, and the battery current increases (this is a lesser negative number). Put that another way, as the MET in sunlight increases, the IHU temperature increases and the circuit current decreases (greater negative number). However I don't know why the circuit reports a negative current, or even if the voice tlm is accurate. I'd be grateful for any comments. 73 de Andy G0SFJ .

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Netbooks again
by ANTHONY JAPHA 21 Sep '11

21 Sep '11

All, I received many helpful comments about the use of netbooks. Thanks to all. As it turned out, I got an ASUS netbook, which takes more than 5 pounds off the weight of the equipment used for my occasional portable satellite work. The hard part was finding a USB to serial port adapter that works. The job is to run 2 of these adapters to control the frequencies of 2 FT817 transceivers to correct for doppler shift. One FT817 is used for Rx, the other for Tx. The doppler shifts for Rx and Tx differ. What's needed is CAT control by SatPC32 software, which is a terrific program. The computer runs Window 7. After trying 3 adapters that didn't work, the problem was finally solved by using the USB to serial adapter made by Sabrent, Item CB-FTDI. This adapter is sold by Elecraft as the CAT cable for the K3 (Elecraft part KUSB). Now I have full freq. control to use with the CW/SSB satellites, just as I had with the much heavier laptop that the netbook replaces. (It needed only 1 adapter because it had a serial port, and an old Radio Shack adapter worked well.) 73, Tony, N2UN

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FM02 K3NXH/4 AO-51
by Chuck Gress 21 Sep '11

21 Sep '11

FYI for those who may be in need of FM02 on AO-51.I will work the 20:09 UTC pass on Saturday September 24th. ChuckK3NXH

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Ao51 reports.
by mm0kjg 21 Sep '11

21 Sep '11

Hello there. Am looking for any reports of my Call being received Stateside during any of the Ao51 passes. I only have a small humble station consisting of Ic-910 in to a dualband vertical on my chimney and am considering buying a pre-amp for 70cm . If am not being heard Stateside on the West passes from my locator Io85iv Ill maybe not spend money on a preamp?. I have had 2xcontact with KB1RVT so we shall see. Please email me or send a message on here. Thanks and 73's Kev MM0KJG

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UARS Keps Enclosed
by Bryan Herbert 21 Sep '11

21 Sep '11

These are current as of this morning and seem to be accurate when compared to the NASA mission status page. UARS 1 21701U 91063B 11263.18833764 .01299762 11120-4 56017-3 0 6054 2 21701 56.9440 281.4376 0013731 14.2607 345.8929 16.21836581108546 Until last night the altitude of UARS varied between 130-140 miles. As I type this it is at 127 miles and appears to be gradually dropping. If you have Ham Radio Deluxe v.5 add the 'Visual' sats group and you will see UARS listed. -- Bryan Herbert - KE6ZGP Newhall, CA. DM04RJ USA http://bryanherbert.com http://twitter.com/ke6zgp

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TP50CE Special Event Station Satellite Operation
by JoAnne Maenpaa 20 Sep '11

20 Sep '11

This would be too late if we waited for the weekend AMSAT News Service news cycle: DXNL 1746 DX Newsletter - Sep 21, 2011 included this item: F, FRANCE The "Council of Europe Radio Amateur Club" (CERAC-TP2CE) is going to activate the special event station TP50CE in all modes on all bands (maybe also satellite) on Sep 23/24. Occasion is the 50th anniversary of the European Social Charter. OPs will be Sergiy,F0EQE, Oleg,RV3DH, and Sparky,RW3AH. QSL via F5LGF. See also: http://ewwa.free.fr -- 73 de JoAnne K9JKM k9jkm(a)amsat.org Editor, AMSAT News Service

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CubeSat Deployable Boom
by Trevor . 20 Sep '11

20 Sep '11

Drexel University are doing some work on a deployable boom for Cubesats, see http://www.uk.amsat.org/2011/09/20/cubesat-deployable-boom/ 73 Trevor M5AKA Join AMSAT-UK at http://tinyurl.com/JoinAMSAT-UK Sample newsletter: http://www.uk.amsat.org/on_193_final.pdf ----

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Observations of arissat signal at 52.48 degrees North
by andy thomas 20 Sep '11

20 Sep '11

Guys and gals I have a modest setup here observing Arissat-1 with a yagi fixed in azimuth and elevation and automatically reording. The sstv signal is detectable without a one transitor preamp but only reproducable with it. The most important thing about the setup is the orientation of the receive antenna. It is pointing at approximately 210 degrees and is fixed. You might ask why not set it at the aizmuth of the maximum elevation, which is what I always do for telemetry cubesats. First of all my answer is that I get better pictures at this azimuth. Secondly as I said to Colin G1IVG I think I know why. If you go to the front page of my website http://www.andythomas.eu and scroll down you'll see a sequence of photos I took of the ISS as seen in my telescope. I was surprised how the attitude of the spacecraft changed as it approached 51.6 degrees (the orbital inclination and therefore the maximum latitude subsatellite), then went away relatively southbound (and of course eastbound). We are at 52.48 degrees North. My thesis is that Arissat-11, which is on more or less the same orbital inclnation, exhibits the same change in attitude as it reaches 51.6 latitude, relative to us, so the antenna is not shielded and therefore the signal level peaks. As the signal level is marginal I can detect this slight improvement. I've sent a copy of this to theWelland Valley ARS for comments and would appreciate your comments too. 73 de andy g0sfj

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