Snaproll
Post Laureate
Reged: 02/20/04
Posts: 3824
Loc: Wisconsin
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I just picked up a used Skyscout at a swap meet and have been noodling with the thing.
Long and the short of it is there were no "battery sleeves" in the battery compartment, just the compartment itself and cover. I assume these must be some kind of shielded tube to keep the batteries from leaking EM and messing up the digital compass? Any suggestions for a field retrofit?
Messing with the thing, it's about 5 degrees off on locating targets, yet on identify it's pretty much on the bright stuff, (it did miss Polaris by about 5 degrees though).
I bought it primarily for the audio portion for outreach. Still, I would like to try to get it working properly. Any suggestions on the sleeve issue?
Thanks 
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-Jim-
Happiness is a clear sky and a Denk II
old AP images and some new C14 Hyperstar images
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Stephen S
sage
Reged: 08/21/07
Posts: 214
Loc: San Diego, CA
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I've wondered about the battery sleeves myself. My understanding is that they are designed to minimize interference. Not sure how they do so but I've read that Celestron will not tell you what they are made of (proprietary information). That said, you might want to contact them directly to see if they will send you a replacement set. No harm in asking. 
Edited by Stephen S (07/31/09 01:58 AM)
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Snaproll
Post Laureate
Reged: 02/20/04
Posts: 3824
Loc: Wisconsin
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I'm guessing they work like a "Faraday cage". Basically this is like a microwave oven. If you encase something emitting EM in an insulated metal shell, it grounds the EM waves so they don't come out of the box. Interestingly a Faraday cage works in reverse. If there is a nuke attack or EMP pulse, toss your computer and radio into your microwave oven and it should protect the devices from the EMP.
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-Jim-
Happiness is a clear sky and a Denk II
old AP images and some new C14 Hyperstar images
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Stephen S
sage
Reged: 08/21/07
Posts: 214
Loc: San Diego, CA
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Very interesting. So this gives me an idea. I wonder if credit card sheiding sleeves would work to help minimize interference with the SkyScout. My understanding is that this is what credit card shielding sleeves do as well. Might work and might given higher accuracy to the SkyScout. Just a thought. If you don't have any credit card sheilding sleeves, my guess is that you can get them at your local bank (also used with ATM cards).
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C9.25 XLT (Arges), Vixen ED100sf (Liberty), Coronado PST (Sunny)
Celestron CG-5GT, Vixen Porta Mount
40mm Pentax XW, 27mm Panoptic, 13mm Ethos, 12mm Cemax,
7mm Pentax XW, 4.7mm Meade UWA, 8-24mm Celestron Zoom
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Snaproll
Post Laureate
Reged: 02/20/04
Posts: 3824
Loc: Wisconsin
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For anyone following this thread, I'm trying something. It sounds like the stock battery sleeve is a tube of thin aluminum. So I'm guessing the shields should be conducting but non ferrous.
I went to the hardware store and found some brass tubing that fits the bill, which nicely fits AA batteries. I'm also assuming that they may work better than the stock battery sleeves because they are thicker. The previous SS owner said he bent one of the sleeves by accident. The brass tubing is very rigid, so I assume a thicker wall which may help. If the material is correct, non farrus but conductive, then these should work better than the stock shields. I'm sure Celestron is trying to make stuff as cheap as possible, hence the thin aluminum tubes. If so, then the brass tube should work much better.... but I won't know until tonight.
I cut two lengths and installed them in the SS. I took it for a test run. I asked it to locate Polaris, which I know where it should be. It appeared to point more accurately than it did last night but I won't know until it is dark tonight.
I'll update what I find.
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-Jim-
Happiness is a clear sky and a Denk II
old AP images and some new C14 Hyperstar images
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Tek465
super member
Reged: 06/18/07
Posts: 128
Loc: Show Low, Az
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Try this stuff from Electronic's Goldmine.
Rare Ultraperm 80 Shielding Sheet ( http://www.goldmine-elec-products.com/prodinfo.asp?number=G16600A )
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Z10 Dob w/ Telrad
Celestron 15x70 binoc
SkyScout
FirstScope
Meade ETX-60AT
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Snaproll
Post Laureate
Reged: 02/20/04
Posts: 3824
Loc: Wisconsin
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Thanks. It's interesting and got some more information for me on what a 'battery shield' may consist of.
It looks to be a combination of nickel and iron, which would make it somewhat ferrous. If I recall, nickel is not ferrous, and this stuff is 84% nickel. Brass is not ferrous, but it is a conductor. Hmmmm, guess I'll just have to wait and see if it works tonight.
Thanks for the info.
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-Jim-
Happiness is a clear sky and a Denk II
old AP images and some new C14 Hyperstar images
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Snaproll
Post Laureate
Reged: 02/20/04
Posts: 3824
Loc: Wisconsin
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FWIW, the brass sleeves seemed to have solved the problem. As of last night it was pointing fairly accurately, a whole lot better than the night before. It could just be satellite geometry or something, but the locate and identify were pretty much spot-on on all targets last night. I suppose it could also be me getting more familiar with sighting the thing or handling it more accurately. In any event, it's going from the astro junk pile to the "Maybe I can use this" pile.
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-Jim-
Happiness is a clear sky and a Denk II
old AP images and some new C14 Hyperstar images
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Stephen S
sage
Reged: 08/21/07
Posts: 214
Loc: San Diego, CA
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Jim:
Thanks for the update. I think it's just a matter of time before I loose my battery sleeves. Good to know there are other options.
Thanks! Steve S
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C9.25 XLT (Arges), Vixen ED100sf (Liberty), Coronado PST (Sunny)
Celestron CG-5GT, Vixen Porta Mount
40mm Pentax XW, 27mm Panoptic, 13mm Ethos, 12mm Cemax,
7mm Pentax XW, 4.7mm Meade UWA, 8-24mm Celestron Zoom
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Snaproll
Post Laureate
Reged: 02/20/04
Posts: 3824
Loc: Wisconsin
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Yeah, I'll know more when I use it tonight, but it seemed to make a heck of an improvement.
--------------------
-Jim-
Happiness is a clear sky and a Denk II
old AP images and some new C14 Hyperstar images
|
bjnicholls
journeyman
Reged: 05/28/08
Posts: 7
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The battery sleeves are mu metal. That's an iron-nickel alloy that's highly permeable to magnetic fields and they're installed to prevent magnetic interference from the field around the batteries themselves. Problem is, mu metal can become magnetized. My shields are now causing the magnet icon to be perpetually active and the device is no longer accurate. Take off the shields and the Skyscout works fine (as reported in other treads). My brother has access to a degaussing coil so I'm going to see if he can neutralize the field in these shields for me. I'll report back on what we find out. Seems like Celestron needs to offer replacement sleeves since they can become the very problem they're supposed to prevent. There are alternative field shielding materials. Mu metal can't be shaped without then requiring annealing in a neutral gas atmosphere - not something the average buyer can do at home.
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bjnicholls
journeyman
Reged: 05/28/08
Posts: 7
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I'm reporting back with the results of degaussing the battery sleeves. After degaussing, the sleeves have restored accuracy to my Skyscout.
I was wrong that the Skyscout worked fine with the sleeves off. The magnet icon quit nagging and precision was improved, but there was still significant error.
I'm now storing the sleeves without batteries installed. The batteries shouldn't produce a field unless they're providing current, but perhaps some battery casings become magnetized and that field is eventually picked up by the sleeves.
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dennis47
journeyman
Reged: 10/28/09
Posts: 5
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Does the cover itself not offer any nullifying effect on the battery EM?
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