March 2007 - AMSAT-BB - mailman.amsat.org

Re: P3E transponder and launch
by William Leijenaar 27 Mar '07

27 Mar '07

Hi AMSATs, I am supprized to see that my mode-uv work for the P3e is still remembered :o) I wonder what happened with the mode-uv transponders designed by the other (New ealand, Russian, German and ??) groups ? Lately I only read about the SDX work of NA, UK and DL, but what about the other parts made by other (none NA,UK,DL) hams ? >From the messages I feel that the SDX seems to be the best radio at all, with a larger dynamic range, better aligator killer, better HELAPS etc... SDR technology is very interresting and it should be explored, but somehow I feel that only its advantages are named. So I like to "flip the count" to its other side to have "the pair of scales in balance". About the dynamic range, I wonder how it can be better than an analog receiver. I suppose the RX side (UHF) will not directly be digitalized (it would need an high speed and high power ADC) so there is still an analogue amplifier and down-mixer needed in front. Then there is only the IF part where it can be dynamically be better. I guess with analogue electronics this can also be done :o) I also seen someone mentioned about 1970 electronics, as if todays electronics is only better in IC form. Todays 2007 transistors are much better than in 1970, they are much smaller, and have a better performance. Even analogue style transponders can be made better and smaller size than those in Ao-10, with todays transistors. Have a look at my modern analogue transponder system at: http://www.observations.biz When talking about old technology then HELAPS (or officially called EE&R) is even more older, from 1952 ;o) That the HELAPS works better only due to the "modern" SDR system is not compairing in a fair way. Then you compair 2007 SDR electronics with 1975 transistor electronics. I believe with todays modern discrete electronics the HELAPS system will work equally or even better. The SDR system with zero-IF is a nice system which is very flexible. However zero-IF can have problems with DC-drift over time what gives unefficient ADC use or even ADC clipping. It is also more sensitive for low frequency 1/f noise, and the high frequency digital processing signals are a serious threat on sensitive receiver inputs... (also a problems in modern cell-phone systems) A Near-Zero-IF system might be a solution but is more complex to integrate. The filters at such low frequencies (zero-IF) can be made very sharp, but the same trick can be done in analogue way, with an RC low pass filter :o) Several years ago I present such a bread-bord system as "Quadrature transponder" where I could easily change the transponders bandwidth and change from inverted to none-inverted :o) The difference is that it takes far less power than a DSP does, and it was extreemly KISS... I agree that digital DSPs are more flexible which is good when you like to use the same radio for other modes also. This was my vote for the analog transponder systems :o) I hope the digital SDX works well and hope that its analog sister will also have a chance to do its work and gets its technical respect... 73 de William --- ____________________________________________________________________________________ Be a PS3 game guru. Get your game face on with the latest PS3 news and previews at Yahoo! Games. http://videogames.yahoo.com/platform?platform=120121

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Pre-amp for IC-910h?
by m0ady＠m0ady.org.uk 27 Mar '07

27 Mar '07

Hi... I am thinking of buying a masthead pre-amp for use with the Icom IC-910H for both satellite and terrestrial work. There are the AG-25/35 units from Icom which are specially designed for use with the 910. But I have seen the SSB Electronics units on the web (SSB-SP-2000/7000) and also the Microset units (PR-145A/430A) and wonder if these devices perform better than the Icom units. Also, would the SSB/Microset units require a sequencer. I would be interested to hear from anyone who has been down this road with an IC-910H. Thanks in advance, 73 Martin M0ADY. -- Martin Grundy (M0ADY) <m0ady(a)m0ady.org.uk> AMSAT-UK: 6314

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RAFT packet satellite assistance needed
by Robert Bruninga 27 Mar '07

27 Mar '07

RAFT's packet-to-voice circuit only works in the dark, and in a few days, RAFT will begin entering the late evening time frame when Northern Hemisphere stations can again use it. RAFT is nearing its mission life time half-way point. It has decayed down to 180 nm and will re-enter before the middle of August. Due to its low orbit and small footprint, we need command stations in the Southern USA between Arizona to Georgia to help us conduct our primary mission of detecting the 218.98 MHz radar fence when it flies through it. We need command stations in those states because they are near the radar fence and will be in the footprint of the radar. The ideal command station has these atributes: 1) A reasonable 2m beam for ops on 145.825 2) A packet TNC 3) A familiarity with dumb-terminal TNC operations such as A. Connections, Converse, UNPROTO, etc B. Remote sysop logon of Kantronics TNC's 4) Desireable, is some experience with UI packets and APRS The objective of these southern command stations is to logon, send the command to activate the RAFT Radar receiver for 1 minute in anticipation of passing through the fence. Then hopefully recording any audio heard on the downlink (145.825). Of course, once the radar receiver is on, everyone in the footprint should be able to hear it. For info, see the ANDE-RAFT operations page: http://eng.usna.navy.mil/~bruninga/ande-raft-ops.html And for more info on the 216.98 MHz radar receiver, follow the links to the RAFT design pages. If you meet the criterial above, lemme know. Bob, WB4APR. US Naval Academy Satellite Lab

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Yeasu G-5400 AZ
by Steve kb9ups 27 Mar '07

27 Mar '07

Hello All, I'm looking to find an AZ rotor unit for my station. I found a EL rotor and control box, but need the AZ rotor. Any around? Yeasu G-5400B Steve/kb9ups AMSAT area coordinator, Toledo, Oh. AMSAT area coordinator, Streator, IL. www.qsl.net/kb9ups _______________________________________________ Join Excite! - http://www.excite.com The most personalized portal on the Web!

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Re: Upcoming Cubesat Launch
by G0MRF＠aol.com 27 Mar '07

27 Mar '07

Can anyone confirm that Cape 1 sends a combination of 9600 packet and CW transmissions? _http://ulcape.org/wiki/CAPE1_Telemetry_ (http://ulcape.org/wiki/CAPE1_Telemetry) I don't have 9600 but I can do CW ! Lets hope the launch delay is not too long Regards David G0MRF

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Cubesat launch delayed
by bklofas＠calpoly.edu 27 Mar '07

27 Mar '07

Hey Everybody-- The CubeSat launch has been delayed past the current launch window. More information will follow in the next few days. -- Bryan Klofas, KF6ZEO Cal Poly State University

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ao7 reliability
by Patrick McGrane 26 Mar '07

26 Mar '07

Greetings from Pat N2OEQ Just a short note to clarify my comment that the older AO-7 technology is reliable after so many years not because the computer and batteries failed, but because the transponders still operate. I love those big old resistors Hi Hi. 73, pat

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FS: Yaesu FT8900R quadband FM rig
by John Geiger 26 Mar '07

26 Mar '07

I have for sale a Yaesu FT8900R Quadband (10m/6m/2m/70cm) FM rig in very good condition. Does 50 watts on 10-2m and 35 watts on 70cm. It does dual receive, so it works great on the satellites, and will do crossband repeat so you can work 10m or 6m using an HT around the house. The 8900 comes with the mic, power cord, manual, and original box. I am asking $340 shipped in the US. 73s John W5TD ____________________________________________________________________________________ Don't pick lemons. See all the new 2007 cars at Yahoo! Autos. http://autos.yahoo.com/new_cars.html

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P3E transponder and launch
by Patrick McGrane 26 Mar '07

26 Mar '07

Greetings from pat n2oeq I have been looking forward to the launch of P3E which I thought was going to be this year. I am concerned about the germans use of the SDR technology over william Liejanier's transponder design. I am of the belief that signal processing presents a loss in the path, please correct me if I'm wrong. Williams Hamsat transponder is excellant and made me very interested in P3E. Besides making the voice unnatural, are other modes allowed through the SDR transponder? Does the Helaps system compensate for the loss? I'm of the Keep it simple discipline as once its up there nothing can be done to fix it. If amsat-dl is monitoring , please update your website and provide a direct Paypal donation utility. Thanks to amsat-na for the donation to P3E recently. 73, pat

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CubeSat LAUNCH DELAY
by Ralph Wallio, W0RPK 26 Mar '07

26 Mar '07

A launch delay has been announced. Details to follow when decisions are made. TNX es 73 de Ralph Wallio, WØRPK W0RPK(a)netINS.net http://showcase.netins.net/web/wallio/ Hubbert's Peak - The Mother of all Perfect Storms

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