A lesson for all the kiddies ot there!

[barx1963 (Malcolm)]

Well managed to get the beast out last night for only my second observing session in about 2 months!!!
Got it all set up, checked the collimation let it cool for an hour or so, rechecked collimation as per usual and chucked in the 34mm and started on a few brighter objects. Views weren't spectacular but I was suspecting there was a fair bit of high thin icey cloud about, but was just happy to see something!
When I was trying to find the Little Gem neb in Sag, I chucked in the 13mm Nag, views were terrible, almost no stars would come to focus and they all appeared to have 'wings'. So I rechecked the coll, both with cheshire and laser. Rotating eyepices made no diff and same effect occured with all EPs, even the 34mm. Went through all the usual suspects, foreign objects on the mirror and secondary, damage etc.
I then discovered that in the 13mm if I defocused, the image of the secondary was very blurry, defocusing the 34mm I could see a localised boiling effect. Suddenly I realised what I had done. The little Dew Heater I have on the secondary was a full power, plugged into the wrong socket in the controller, the holder was so hot I could barely touch it.
Once it had cooled (after about 1 hour) views returned to normal, but I was still frustrated at wasting a couple of hours precious observing time.

Malcolm

[Ric]

Lucky you realised Malcolm.

[pgc hunter]

yikes had no idea dew heaters are so powerful!

I always keep mine under 50% power, it's more than adequate even in heavy dew. The straps I'm not using make pretty sweet hand warmers aswell

btw, 2 sessions in 2 months? That's an amazing effort in these abhorrently Melbournecast times. My tally for the last two months is exactly 0.

[multiweb (Marc)]

Originally Posted by barx1963

The little Dew Heater I have on the secondary was a full power, plugged into the wrong socket in the controller, the holder was so hot I could barely touch it.

lucky you picked it up on time and nothing was damaged. Whenever I have connections that are a 'no-no' in the drak I try to put slightly different adapters on the +/- plugs so they don't fit. Only on way. Works quite well for me.

[Jen]

lol Malcolm sounds like you had an interesting night
I will remember that one when i finally get some dew heaters

[barx1963 (Malcolm)]

Normally I plug the Telrad heater into this plug as I have found that it needs to be really warm to work at all, and just run the secondary at 10%. Must rethink the way I have it set up

Malcolm