[amsat-bb] Re: DJ-G7T programming cable question
There is considerable value in making new members of the community aware of common and sometimes very informative published resources, however. There's a wealth of information in those that should very well be tapped especially for technically complex questions. The trick is in positioning a referral to those resources in such a way that it doesn't feel like an "RTFM" brush-off, which in many cases, it really isn't. I run into this a lot in tech support, and the best positioning I've found is to give at least a gloss of the subject matter in a reply, and then include "this is covered in more detail at (insert resource here)". Sometimes the brief gloss of the answer is all that's needed, but for the times when it's not, following up with the resource referral leaves the person equipped to gather more detail on it from that. On Jun 9, 2009, at 5:13 PM, David - KG4ZLB wrote: > Whether or not a question is raised after someone has actually tried > to work it out for themselves or not is immaterial. > > If this reflector, which lets face it is concerned with some fairly > high level stuff in comparison to normal ham radio operations), is > going to go the way of responding to a perfectly reasonable question > with the reply of "read the **g manual", then newcomers and > interested observers are going to beat a hasty retreat thinking that > AMSAT is elitist. > > We must not be seen to be typical of the 'those that know' wanting > to protect their playground mentality. > > I have asked some downright stupidly basic questions on here over > the years and have always been responded to with friendliness and > professionalism even though I have often had a mental picture of my > "helpers" banging their heads against a wall in frustration. But on > the back of that I have been able to help with other people's issues > where the same question has arisen. > > If questions offend then use a combination of filters and the delete > key. > > My 2 peso's worth. > > David KG4ZLB > > > > Justin Pinnix wrote: >> Well, there's a guy on eHam who responds to every question with >> "that's a >> stupid question" or "go look it up". That just doubles the amount >> of noise >> :-) >> >> I'm all for experimenting as well, but randomly plugging unknown >> devices >> together is a good way to blow something up. What if the >> programming cable >> is putting out +-12v (EIA RS-232) but the radio only wants to see +5 >> (CMOS/TTL)? >> >> 73 de AJ4MJ > "Good, 'cause, you know, we want to report that the country's a lot stranger than it was a year ago." -- Toby Ziegler ___ Sent via amsat...@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Water as a rocket fuel
On Aug 27, 2009, at 10:48 AM, John Heath wrote: > On boeard electrolysis of water to produce Hydrogen/Oxygen rocket > fuel. > > An most interesting paper on the subject at > https://e-reports-ext.llnl.gov/pdf/236614.pdf > It does work in space. Well, using a URFC for the electrolytic separation takes care of most of the ullage and gas separation problems I mentioned in an earlier post. (And having arrived at that solution independently, I'm convinced it's a viable research path if nothing else. ;) It also has the benefit of being able to turn the separated H2 and O2 back into water and electrical power (minus losses, of course) if needed -- not sure what additional support systems that would need, but it's a tantalizing side benefit. Storing the water still requires some means of eliminating unnecessary headspace in the water tank to avoid the requirement for ullage -- I'm still partial to the idea of a sylphon-type bellows inside a slightly larger tank pressurized with helium or nitrogen -- to maintain water flow into the FC. And as before, these are *not* hypergolic fuels, so using them in engines still requires exactly timed valve opening/closing rates and synchronization between fuel/oxidizer valves and ignition on startup, which are considerably more complex systems than the ones used to control hypergolic engines and RCS thrusters. (All a hypergolic engine has to do is open and close the fuel/oxidizer valves at the right rates and relative timings.) That being said, it's an intriguing idea. Regenerative fuel cell based electrolysis is pretty interesting in and of itself. :) ___ Sent via amsat...@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Azimuth question
On Jan 9, 2010, at 1:47 PM, Dave Guimont wrote: > At 11:37 AM 1/9/2010, you wrote: >> Randy, >> True North is used as a reference. Magnetic North changes with >> observer >> location and time. >> > > Art, what does mag north have to do with time?? Magnetic deviation changes slowly over time as the earth's magnetic field changes. The rate and current deviation are usually pretty precisely known for most areas. "No nation was ever so virtuous as each believes itself, and none was ever so wicked as each believes the other." -- Bertrand Russell ___ Sent via amsat...@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Arecibo grumble
So they're basically not allowing for the 2+ seconds for the signal to *get* to the receiving station plus the 2+ seconds for the reply to get back? Laws of physics and all that. :p On Apr 18, 2010, at 4:33 PM, Idle-Tyme wrote: > Or how they never waited long enough after cqing to get an answer. > half > the time they would call cq tubne a bit and in like 2 or 3 seconds > theyd be cqing already! ___ Sent via amsat...@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: 'Zombie-sat' and the clever orbital dance
On May 25, 2010, at 2:27 PM, Luc Leblanc wrote: >> The BBC are running the video on their website >> >> http://news.bbc.co.uk/1/hi/science_and_environment/10150614.stm >> >> 73 Trevor M5AKA > > > They will need a space fly swatter... More seriously some kind of > solution will have to be found to discard useless space debris and > junk. It's all in the delta-V. If you can apply enough to put the perigee in the upper atmosphere, the orbit will eventually decay to where the object deorbits. Everything in LEO encounters enough drag to end up in the atmosphere sooner or later, whether it's within a year, within ten years, or within a hundred years, sooner or later it will fall out. HEO and above, you pretty much have to apply external delta-V to get the perigee down far enough. The problem with dead HEO and GEO sats, and a lot of the GTO booster stages that got them there, and all the loose bits of shrouds, interstage thrust structures, and so on, is that their perigees are far enough above the atmosphere that if left completely alone, they'll still be there tends of thousands of years from now, because there just aren't any forces acting on them that are strong enough to either deorbit them or kick them up to escape velocity and out into solar orbit, and the immediate problem with *that* is that at $36k-$550k/ kilogram, it's still too expensive to launch much more than new working sats to GEO. If the cost comes down to where it's practical to launch a semi- autonomous deorbiting "tug" of some sort to grapple junk and push it to a low enough perigee, with some kind of propulsion that can supply large amounts of delta-V for a relatively small onboard fuel load, then a lot can be done about HEO/GEO junk. But all of those are big ifs, and doing anything like that with our current propulsion tech just isn't feasible due to diminishing returns. You're pretty much looking at some kind of antimatter rocket to be able to do that kind of job. "A process cannot be understood by stopping it. Understanding must move with the flow of the process, must join it and flow with it." -- the First Law of Mentat ___ Sent via amsat...@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
