From: Mark Gaffney <markgaffney@mac.com>

Date: April 21, 2009 5:34:55 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] firewire cables...


Hi Milton, The Unibrain repeaters are rated at up to 110 metres I noticed. I don`t know in what configuration though (I mean do I need a 2nd {before the extender cable} or third repeater[ as you say in series within the first 4.5 metres] to do it safely?). For focusing now I have a 2nd monitor on a long VGA cable ready to be taken outside on a portable picnic table & take my keyboard & mouse out on M-F usb extension cables. Today I`m getting a new Apple keyboard & mouse so I don`t have to alter my permanent inside set-up at all. If, as you say I have problems with data rates or something else I`ll have to think about taking the Mini outside (it is fairly portable after all). It`s just that I have to frig around moving it`s cables, power source & all the other paraphenalia etc. every time I`m imaging in that case! At present with just the Flea 2 everything is hunky-dory. I also now have an Orion dew zapper powered by my Celestron battery tank! By the way do you do all your developing on the same G4 laptop!!

Mark.

On 22/04/2009, at 7:25 AM, Milton Aupperle wrote:


Hi Mark;


Frankly, the only way to know is if you try it out. It may manifest

in different situations too. For example, if your running the cameras

at high frame rates, it may run into issues where as at lower rates

it might not.


And you are way out of spec with your cable distances, as you should

never be over 4.5 meters without a repeater between them for FireWire

400 speeds.


http://en.wikipedia.org/wiki/FireWire


I'm still curious why you wouldn't move the Mini and Screen closer to

the Telescope rather than long data cables. It also makes it easier

to achieve focus too when it's all beside you.


When your using it, you could get a card board box, put the mini and

LCD inside it and then wrap the box in a plastic bag as a light

rain / dew shield. It won't survive a monsoon or heavy rain but, it

would give you some relief for a brief shower or dew.


That's what I plan on doing next year in the winter for my Laptop so

I can image at -30° C or colder. The plastic bag should trap enough

heat from the heating pad to keep the laptop from freezing up, which

happened last winter several times when it dipped down to -38°C or

-50°C with wind chill (the digital thermometer doesn't go any colder

than -50°C).


HTH..


Milton


On 21-Apr-09, at 1:55 PM, Mark Gaffney wrote:


Hi Milton & others, I`m at present running a 10 metre 6p to 6p cable

from the firewire 400 port on my Mac Mini to a Unibrain repeater/hub

similar to this; http://www.unibrain.com/Products/p1394/FR400.htm

from that I have the ACC-01-2007 4.5 metre 6 pin to 9 pin locking

IEEE-1394a to 1394b cable from the PGR development kit going to my

Flea 2. I hope to also run a 3 metre 6p to 6p cable from the repeater/

hub to my TIS DBK 21 A F04.AS. My question is this; Can I extend the

cables running from the repeater/hub an extra 4.5 metres by adding a

male to female firewire extension cable to each of the cameras? The

extra length may be necessary when I move to my projected new

telescope pad in the front garden. I already have one of the 4.5 metre

extension cables but stopped using it a while ago when I had problems

with the long connection-this was before obtaining the Unibrain

repeater/hub. Mark.




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