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ZL3AI > APRDIG 21.02.04 17:39l 264 Lines 10222 Bytes #999 (0) @ WW
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Subj: TAPR Digest, Feb 19, 3/5
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From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
Subject: Re: Amperage rating of cigarette lighter plug
From: David VanHorn <dvanhorn@cedar.net>
Date: Thu, 19 Feb 2004 12:25:34 -0500
X-Message-Number: 16
At 11:54 AM 2/19/2004 -0500, blitz wrote:
>I might caution users about gell cells as Ive done before. Gell cells are
>for long term low current draws, and any attempt at drawing a large amount
>of current, even for a short period of time is futile.
They do have definite ratings on these parameters.
Check the data sheet for your particular cell.
>Due to their gelatin electrolyte, they charge slow and discharge show,
>this is due to an electron mobility problem caused by the gelatin
>electrolyte. (The price we pay to be spill-proof) They are designed for
>burglar alarms and standby power sources where current draws are fairly
>constant.
Of course the Optima batteries use this same technology for vehicle
starting applications.
http://www.optimabattery.freeserve.co.uk/english_optima/red_top_optima.htm
>Utilizing them for high current applications like PTT high power will
>result in excessive terminal voltage drop, mimicking a bad cell when the
>cell is perfectly fine.
I have no problems with this, running two FT-1500's at full power.
>Connecting one in parallel with a car's charging system without adequate
>fusing and isolation is asking for a fire or possible explosion if the gel
>cell shorts out.
Of course.. In my rig, I have a 60A at the battery, to protect from shorts
to ground, and a 25A resetting breaker in the battery box, to protect it's
output.
>Be advised, they will. Having used both gel packs and motorcycle batteries
>extensively for backup power for electronic devices in cars, you also want
>to limit charging current to a motorcycle battery to around 1-5 amps
>depending on the battery rating. Overcharging will result in sulphation,
>stink, expulsion of electrolyte (acid) from vents and the possibility of
>warping the plates and causing damage ranging from a bad battery to an
>explosion. Use care, read manufacturers ratings and always fuse.
Given that the charge voltage for the Gel is slightly higher than the auto
battery, overcharge seems unlikely, and I've seen no problems in nearly 2
years this system has been installed. The Gel still has full capacity, as
nearly as I can measure.
>A shorted battery of any type from gell cell to motorcycle can produce
>sufficient current to start fires, especially in small gauge wire.
A good reason to use flight wire, and fuses.
>In the setup you describe, do you see any strange resets of the TNC?
>Especially during starting?
Nope.
>Be cautioned that small voltage drop in that smaller wire feeding is quite
>capable of starting a fire under certain circumstances. I dont want to
>sound too alarmist, but Ive seen a $100,000 motor home go up in flames from
>stupid stuff like this.
?? The #4, or the #8? If I get enough current for a significant droop in
those, then there are severe problems. Again, the 60A "aw sh*t" fuse on the
car battery end is there specifically for this sort of catastrophic
failure. The breaker in the battery box will self-reset, but only after
the short is removed.
>For any standby power like you describe, I'd use a DC to DC converter to
>keep the secondary battery charged. They have the added advantage of having
>a small voltage boost, so the charge output can be a little higher voltage
>so battery maximum capacity can be achieved. When you use a diode in
>series, you automatically loose that advantage, as charge voltage will
>always be .7v lower than alternator output.
That's what I was planning to do, but so far it hasn't proven necessary.
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Subject: Re: Tetroon construction?
From: Jeff King <jeff@aerodata.net>
Date: Thu, 19 Feb 2004 12:56:41 -0500
X-Message-Number: 17
On Thu, 19 Feb 2004 09:25:49 -0500, Robert Bruninga wrote:
>I was suprised by the photos that the balloon was clear. Wasnt this
>a solar-thermal balloon? I asumed that there would be some "black"
>somewhere inside to absorb the solar heat? Maybe black smoke?
Just think about how warm it gets inside a greenhouse. The idea is to heat
the air, not the envelope. I believe Robert once used a black envelope and it
was suspected of melting at high altitude.
I have seen some human solar balloons that have a black absorber in the
center of them, but they still had a clear envelope.
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Subject: Re: Tetroon construction?
From: "Robert Bruninga" <bruninga@usna.edu>
Date: Thu, 19 Feb 2004 13:56:41 -0500
X-Message-Number: 18
On Thu, 19 Feb 2004 09:25:49 -0500, Robert Bruninga wrote:
>>a solar-thermal balloon? I asumed that there would be some "black"
>>somewhere inside to absorb the solar heat? Maybe black smoke?
Jeff said:
>Just think about how warm it gets inside a greenhouse. The idea is to heat
>the air, not the envelope. I believe Robert once used a black envelope and it
>was suspected of melting at high altitude.
Yes that is why I said "black inside", not on the surface...
>I have seen some human solar balloons that have a black
>absorber in the center of them, but they still had a clear envelope.
Yep, thats what I meant.
Bob
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Subject: APRS Map Manager Submittals
From: Steve Dimse <k4hg@tapr.org>
Date: Thu, 19 Feb 2004 15:34:06 -0500
X-Message-Number: 19
My first draft of the APRS MM submittal page is done, and the backend is
ready to accept data:
http://mm.aprs.net/submit.html
I'm looking now for comments on the data contained in the database, (which
is essentially the data asked for in this form), and for some submittals to
start working on the librarian interface.
At this time, I'm asking for anyone interested to submit a single map, in
order to give everyone a chance to participate, and to give me the widest
variety of data to work with, without having hundreds of files to work
through. The sooner you submit, the sooner it will be accessible through
findU and other applications that can use the APRSMM.
Comments are very welcome...
Steve K4HG
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Subject: MAP Converter?
From: Henk de Groot <henk.de.groot@hetnet.nl>
Date: Thu, 19 Feb 2004 21:49:34 +0100
X-Message-Number: 20
Hello,
A HAM asked me to build a new PocketAPRS map of the west Pacific Ocean. I
could do that, but the map he provided is in AprsDOS .map format instead of
WinAPRS format. All the maps I have build so far originated from the latter.
I can most certainly start hacking to support AprsDOS maps as input, but I
rather avoid it. Does somebody have a converter to convert AprsDOS maps to
WinAPRS? That would save me a lot of time.
The map headers says:
--------------------------------------------------
90 , Lat of NW corner
-90 , Long of NW corner
12 ,Pixels per degree
10.35614 ,LAT of CENTER
-198.0224 ,LON of CENTER
4000 ,Map range from center
1 ,Reserved
--------------------------------------------------
I don't know exactly how to interpret this (yet) but a WinAPRS map covering
the same area would be okay too I guess (most of the time WinAPRS maps have
more detail than the AprsDOS versions).
Kind regards,
Henk.
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Subject: Re: APRS Map Manager Submittals
From: Jeff King <jeff@aerodata.net>
Date: Thu, 19 Feb 2004 16:41:34 -0500
X-Message-Number: 21
What about ownership of submitted maps? Will they remain in the public
domain (assuming they were in the first place) or will ownership revert to
yourself?
I see some talk of this on your main page (that it will be GPL'ed) but not
entirely clear you mean the map data or the positional data.
Also, what is your sourceforge and/or GPL home page?
Thanks
--
Jeff King, jeff@aerodata.net on 02/19/2004
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Subject: Re: APRS Map Manager Submittals
From: Steve Dimse <k4hg@tapr.org>
Date: Thu, 19 Feb 2004 17:00:38 -0500
X-Message-Number: 22
On 2/19/04 at 4:41 PM Jeff King <jeff@aerodata.net> sent:
>What about ownership of submitted maps? Will they remain in the public domain
>(assuming they were in the first place) or will ownership revert to yourself?
I've never claimed copyright of any data or image produced by findU, where
I would be entitled to do so, so I'd hope it would be obvious am not going
to do so with maps where others hold the copyright. I am going to put up
more discussion of the copyright issues when I get the programming done,
and it may not be clear from the submittal form that unless the submittor
certifies the copyright holder has agreed to unlimited distribution by
aprs.net, the map will be refused. The first two choice on the page will
automatically reject the map without even saving it to the disk, the last
two will accept the map for consideration, but the copyright issue would
have to be cleared manually before the map would be moved to the database.
>I see some talk of this on your main page (that it will be GPL'ed) but not
>entirely clear you mean the map data or the positional data.
I'm not asking anyone to make their maps available under the GPL, or give
up any other rights to them, only to allow "unlimited distribution by
aprs.net". People are free to copyright their maps, and do anything the
wish with them, placing them on aprsmm does nothing to change their rights,
other than that specific clause.
In reality, I expect this is a non-issue for most APRSdos, PocketAPRS, and
WinAPRS maps, their creators generally want them widely distributed. Most
geo files seem to reference US government sites on the web, which are not
copyright issues, or like most INF files are created by commercial map CD's
or web sites, which are not eligible for the APRS MM.
>Also, what is your sourceforge and/or GPL home page?
It was announced on the sig a few days ago:
http://sourceforge.net/projects/aprsmapserv/
Steve K4HG
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