Last updated: 28 October 2004
Subject: Home-made ETX-70AT Power Adapter Question Sent: Wednesday, October 27, 2004 17:52:47 From: Greg (firstname.lastname@example.org) Hi, I was wondering if you could help me with this "experiment" I'm trying to do. I've been trying to make a power adapter for my ETX-70AT and I found 2 unused AC power adapter in my basement. One of them says: "INPUT : 120VAC 60Hz 6W" "OUTPUT : 12VDC 200mA" The other says: "INPUT : 120V AC 60Hz 5W" "OUTPUT : 9V DC 200mA" My question is, can I use either of these adapters to power my ETX? Any help you can give me would be appreciated.Mike here: You will need more output; something like 12VDC 1000mA.
Thanks for the help. I tried the 12V 200mA adapter on the scope. It turns on and can move just fine, but when I slew it to the right, it doesn't stop and I cant control and of the axis's. I was just curious, what is the minimum mA you need to operate the scope normaly?Mike here: There is a minimum for tracking and a minimum for slewing at higher speeds. Exactly what those are I don't know. The Meade AC Adapter for the ETX-70 is 1000mA, which covers the highest demands the ETX-70 should make. By the way, don't forget to reCALIBRATE when you swap power sources.
Sorry to bother you again, but I just found an adapter with an Output of 9V and 1.11A. Is that to much output, or would it work?Mike here: I suspect it will work OK.
Subject: Fuzzy image in a 70AT Sent: Saturday, October 23, 2004 21:28:34 From: Tom & Barbara Andrews (email@example.com) This is my first post. Since I bought my second-hand Starfinder, I've been checking this site out for general info on the skies and on Meade scopes. Now I'm in the early days of an ETX-70, which is great fun as a portable (as well as being all I can afford at the moment). I've just been drive-training and while looking at the treetops the image seemed unclear. It was like looking at a film scene that had fuzzy edges to appear like a dream sequence. Moving my eye over the eyepiece accentuated this, as the fuzzy "shadow" changed orientation. The eyepieces were s. 4000 26mm and 9.7mm. They work fine on the reflector, so it isn't them. Wot does it all mean?? Cheers. Tom AndrewsMike here: If the trees are too close you won't be able to focus on them. How is the Moon, which is a fine (but bright) object right now?
Thanks for the quick reply. I'll get back to you when the rain clears and the sun sets. I'm in Sydney and it's 3 p.m Sunday. I will say that, on my first viewing last night, Canopus showed a sharp point with a largish disc around it. A bit like my vision was blurry, but with the star visible in the centre of the light disc. Not being used to refractors, I'm not sure if this is what's described as an airy disc. It may just have been a bit dewy. Cheers! TomMike here: It sounds like you may not be turning the focus knob enough. With the ETX-60 and ETX-70 refractors it can take MANY turns to achieve a focus, depending upon how out-of-focus the image is.
thanks for the quick advice. A star in perfect focus is still at the centre of a faint but luminous disc. If I begin with a 26mm SP at too-distant focus, I turn the focuser counter-clockwise. The disc begins forming just as the concentric circles become visible. It becomes slowly larger as the focus gets better. At perfect focus the star is a point, surrounded by the luminous disc which is (from memory) about half the size of the moon. As I continue to turn, the star disappears out of focus and the disc continues growing slowly. The moon is a different story. It's almost fully washed out by the disc of light. There is enough contrast to see when focus has been reached, but that's all, and the light disc moves according to the small movements of my eye. It's the same through the 9.7mm SP and with the filter. I'm assuming this is not normal. Thanks again, TomMike here: Focus on the Moon so that craters are sharp. Then look at a star WITHOUT changing the focus. Do you still see a large "disk" of lot? It sounds like you are trying to magnify the star's image, which you can't do. Stars will always appear as pinpoints of light (with an airy disk in some instances).
I'm familiar with star images, I just tried the smaller eyepiece to see if it happened with that one also. I did the moon-star test and the disc was still there. (This may be what some call a halo). I've looked with contact lenses, with spectacles in case my contacts were dirty, and with no specs. This is after reading Fraser Farrell's suggestions. It's still there, but the faint background stars are perfect points. I'll try to get a second opinion tomorrow night, in case I have a vision problem, but it only affects the brighter stars and the moon. Thanks again, TomMike here: A Halo could come from dirty optics OR lousy seeing.
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