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Subject: Re: [M]: (OT) Remote observatory Question?
From: Frank Loch
Reply To: mapug@shore.net
Date: Sat Apr 05 09:10:30 1997
>
> I'm in the planning stage of building an observatory in my back
> garden. I like to get everything sorted in my mind before I start
> and am slowly getting it straight. It is going to be a largely remote
> observatory about 50 feet (in wire length) away from my computer One
> thing that has been worrying me for a week now is if I run the wires
> for the CCD camera and the telescope control, can I also run the AC
> power cable alongside them. Will it cause noise on the images or
> interfere with the control of the telescope or CCD camera? If it
> does interfere, what distance should separate the cables to be safe?
>
> If anyone has any experience with this I would be glad it hear from them.
>
Pete -- I think most of us on this forum would tell you that you can
run the scope and CCD cables in the same conduit as the AC power at
least up to 100+ ft.
Now in my case I'm doing just that, but with 30 ft run.
However I did run into a strange problem at first, and if you will
bear with me for a minute I'll discribe it. BTW, visit my website Deep
Space 99 to see my installation.
Now originally, I had my lx200 12" on a roll out dolly that I would
move from my garage to some distance out on my driveway. From my desk
in the house (with desktop PC) my cable run was 110 ft. Battery power was used at the
scope. All worked fine this way.
Then I put the scope on it's permanant pier in my back yard (ie a
different location (seperated from the drive way location bu about 75
ft). The same cables were used and were run through a 30 ft
underground pvc conduit WITH the 120v AC power cable ( for some
accessories)., and battery power cables (battery indoors). The excess cable lengths were coiled
up on the floor by me feet in the house at my desk.
Well, in my CCD images (SBIG st7) all the stars grew whiskers. I tried
many things to get rid of this problem including running a seperate
above ground cable (still 100 ft) to the CCD but now with the CCD cable
widely seperated from the burried power cable. No change -- still
whiskers on all the stars!
Next I took my laptop on a little table out aside of the scope.
Using only the short 6ft cable that came with the ST7 I got perfect
stars and images. Hmmmm!
Then I took the buried CCD cable that was coiled by my feet, and
straightened it out (relatively speaking) and using it again as the
CCD cable the whiskers came back.
Then I took the burried CCD cable, cut out about the 70 excess feet,
spliced it back together and it worked fine --no whiskers-- and it
has been working fine ever since.
Now I'm at a loss as to explain the cause of the whiskers except as
some kind of "interference" that was creeping into the long 100ft
partially coiled and partially burried cable.
The point of all this is that what you want to do should and can
work, but you may run into some unexplanable supprises.
I would be pleased to answer any more of your questions, but then
maybe we should do that by direct e-mail.
Best regards,
Frank Loch
Try Deep Space 99 at http://www.early.com/~floch/index.html
For Gemstone information try: http://ourworld.compuserve.com/homepages/FLoch/