February 2021 - AMSAT-BB - mailman.amsat.org

PSAT-2 SSTV operation change
by Tomáš Urbanec 02 Feb '21

02 Feb '21

We would like to inform you, that PSAT-2/NO-104 transponder and SSTV camera are still going strong. For a long time we were unable to command the sat from Europe due to night passes and COVID restrictions. Now we were able to refresh all the picture memories and we moved the timing of transmissions so that when the sat detects PSK31 signals in uplink, it downlinks the SSTV pictures more frequently and in MP73 format. Feel free to experiment, we reccomend to transmit the PSK signal loop between 400 and 1000Hz in downlink to accomodate between the beacons and SSTV signals. We are still offering interested stations the possibility to command the camera and obtain the pictures of their side of the Earth. Just contact us for info. Good luck in experimenting and have a fun! Tomas OK2PNQ

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Mr Moderator
by Clint Bradford 02 Feb '21

02 Feb '21

Please delete that message I sent five minutes ago - it was rejected due to size. It had a screen shot ... I believe it is moot - the OP lives in England ... Sent from my iPhone

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Mounting Bracket For IC-910
by va6bmj 02 Feb '21

02 Feb '21

I'm looking for an ICOM MB-5 mounting bracket to use on an IC-910. Price negotiable. Contact me off-list if you have one that you'd like to sell. 73s Bernhard VA6BMJ DE DO33fl Sent with [ProtonMail](https://protonmail.com) Secure Email.

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Worm gear drive boxes for AZ and EL
by Mike Hoblinski 01 Feb '21

01 Feb '21

I was wondering how well would a worm gear assembly hold up for AZ and EL drives and what might be the drawbacks. I ran across one persons rotor project that uses worm gear boxes with Nema 21 stepper motors. The gear boxes themselves cost about 45 dollars each and appear to be quite rugged and waterproof. Github https://github.com/YohanHadji/SuperAntennaz Youtube https://www.youtube.com/watch?v=NuH7F1J6nr8 Satnogs https://community.libre.space/t/satnogs-all-metal-box-mountable-rotator/492… Mike N6IMF

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Re: Cubesats
by Daniel Schultz 01 Feb '21

01 Feb '21

I thought that the Cubesat community had annual conferences to exchange ideas on what works, but they still keep making the same mistakes over and over again. Part of training engineers is to teach them to look around and learn from other people's mistakes. >"So the Fox line has met industry standards (3 of 5 deployed successfully)." 3 out of 5 deployed successfully is a pretty dismal industry standard. The "industry" still considers Cubesats to be throw-away disposable space junk whose main function is to train students. (Train them for what is still a good question) They are considered to be successful if the students graduate from their school, they don't need to actually work for any length of time on orbit, or even to work at all after deployment. When Mike Griffith was running NASA, he even advised students to forget about building Cubesats and instead seek internship opportunities in the aerospace industry where they might be exposed to real world spacecraft engineering. A school in my local area recently built and launched a Cubesat under sponsorship of a local aerospace company. The satellite was deployed from the ISS and was never heard from. This local company has extensive test facilities, they could have invited the students to bring their Cubesat over to run a thermal vacuum test for one day at minimal cost, but no one ever thought of doing that. It could have been a highly educational opportunity for the students but reliability has never been part of the Cubesat curriculum. And it is not just student built Cubesats that have reliability problems, I have heard complaints from both Goddard and APL about the poor quality of commercially manufactured Cubesats. Even a NASA-built Cubesat suffered from a failed antenna deployment a few years ago. How long was RadFXsat in the p-pod before launch? Long storage times without battery maintenance could also be a risk factor. There is a reason why larger space missions have access hatches built into their launch vehicle shrouds for last minute inspections and maintenance. I am reaching a conclusion that Cubesats are too small to support the HEO communications mission that AMSAT members desire. Not only are they too limited in power generation and antenna size but they are also lacking in thermal control which is the key to a long lived satellite. If AMSAT were able to raise a couple million dollars we could buy a commercial launch for a larger satellite that would not require so many compromises in its design. We did raise that amount of cash for Phase 3D in the 1990's, albeit in the pre-ITAR days when international projects were still possible. Up until a couple decades ago AMSAT was the only small satellite builder in the world, now we live in a different world than the one we grew up in and we are just one of many such organizations. We have not yet adjusted to our brave new world. Dan Schultz N8FGV

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Re: Cubesats
by Dimitrios Simitas 01 Feb '21

01 Feb '21

CubeSats enjoy a up to a 39% industry average failure rate. From most common to least, CubeSat failure (21%), launch failure (12%), and not ejected and not specified are tied at 2% each. https://www.hindawi.com/journals/ijae/2019/5063145/ Successful deployment made up 61% of the 848 CubeSat launches between 2005 and 2018. So the Fox line has met industry standards (3 of 5 deployed successfully). The hardware, even if purchased to be space tolerant, is still assembled and ground based testing in a educational or not for profit environment is limited compared to the big commercial companies. It's the reason why Es'hail 2's amateur component was built commercially using AMSAT specifications. There is also the issue that as secondary payload CubeSats have been developed to not use active means of deployment. Such as hoping their solar cells, and antennas release. Which is suspected to have caused many failures as has been pointed out. Even so, SpaceX is seeing a 5% failure rate on their $2.5 million Starlink Satellites and even NASA's $4 billion Hubble had issues. Space can be unforgiving. And due to size and weight constraints of CubeSats, unlike larger commercial satellites, it's nearly impossible to build redundant systems to keep the satellite functional after any system failures. The term acceptable failure rate in engineering comes to mind. And expecting perfection out of a CubeSat just isn't going to happen. Dimitrios VA3DSZ

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VUCC Awards-Endorsements for February 1 2021
by Ronald Parsons 01 Feb '21

01 Feb '21

Here are the endorsements and new VUCC Satellite Awards issued by the ARRL for the period January 1, 2021 through February 1, 2021. Congratulations to all those who made the list this month! CALL Jan Feb WA4NVM 1557 1568 WD9EWK (DM43) 630 632 VE7CEW 501 555 NM3B 481 553 N9FN 499 526 N7EGY 502 501 ?? ND0C 450 500 AC9O 359 475 W0NBC 435 437 PV8DX 373 412 KF6JOQ 353 403 AK7DD 376 390 W8LR 300 328 S57NML 205 291 K5ZM 179 277 VE4MM 227 263 VU2LBW 246 260 VE6WQ New 232 KV4T New 219 DG7YEO New 217 KF0QS 115 205 NA1ME 175 200 W4ALF 102 200 WD9EWK (DM41) 176 187 WA8ZID 126 176 DG3YJB New 103 HB9GWJ New 102 VE6BMX New 102 AA8CH (EN84) New 101 AB0XE New 100 KN4ZUJ New 100 KS4YT New 100 If you find errors or omissions. please contact me off-list at <mycall>@<mycall>.com and I'll revise the announcement. This list was developed by comparing the ARRL .pdf listings for the two months. It's a visual comparison so omissions are possible. Apologies if your call was not mentioned. Thanks to all those who are roving to grids that are rarely on the birds. They are doing most of the work! Ron W5RKN

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