Give the Mak credit where its dew.....

[Stu]

My apologies for the appalling pun. I was hoping to have a decent session with my Intes Micro M715D tonight, and popped it on the GP-DX to cool soon after I got home.

Aligning the Mount is fairly simple, but tonight it reset itself a couple of times whilst slewing. I’m wondering whether the power supply is not up to the job, I will check how much current it needs and then go from there. I’m fairly paranoid about ensuring the polarity is correct, not wanting to blow the Skysensor 2000PC controller up having looked for one for so long, so will be ultra cautious with any change.

Anyway, the reason for the title. I slewed to a few objects such as M57, 27 and 15, and was fairly uninspired. They just seemed dull. I had kept the scope capped and had the dew shield fitted, so had no reason to think that it would have dewed up, but how wrong I was! The front corrector was covered front and back, plus the primary! I’m not sure how that was possible, although I recall my OMC200 doing something very similar at PSP one year.

I basically canned the session then, using Mrs Stu’s hairdryer on cool to dry the scope out internally before packing it away. I do need to find a solution. Obviously a dew strip is required, which I have, but I also need to get the mirror fan going which will help the cooling too.

So, I should not judge the performance of the Mak with every optical surface dewed up, that’s not really fair! Really looking forward to getting a decent session with it soon though.

 

[Space Hopper]

That must have been a scary moment to see the corrector and the primary like that.

I've always had a fascination with Russian Maks : hopefully you'll get some good sessions with it soon .

[alan potts]

I wanted one of those scopes Stu but out here it was not possible for the reason there was a Y in the day of the week. I bought a SW 180mm Mak and I have found it to be excellent. It was to stop me wanting a 6 inch APO refractor, which didn't work, still want one. I have found though keeping it outside helps no end with cool down as it is always witnin a couple of degrees of open air temperature. I can imagine bringing it from the house would take at least 90mins to cool off and probably longer.

Alan

[Stu]

6 hours ago, Tubby Bear said:

That must have been a scary moment to see the corrector and the primary like that.

Thanks Tubby Bear. I confess I was shocked that it had dew up so comprehensively so quickly.

@alan potts it was stored in its case in a cool out building for a few hours before, so should have been close to ambient. I’m not sure what the answer is; running the fans would surely just introduce more damp air into the tube causing further dewing? Or would the airflow cut this down? The Mak has a fan which is designed to pull air across the primary, and in from vents around the front corrector. Any thoughts appreciated.

[dweller25]

@Stu

I try not to run the fan on my 715 as the internals dew up quickly.

I have had massive success with dew prevention with a C6 - I wrapped two layers of silver reflectix around the OTA to insulate the warmer air in the OTA from the colder external air.

I have yet to try it on the 715 but would expect the same success - the reflectix costs around £15 from B&Q so it’s a fairly cheap solution and can be undone 

[Stu]

15 hours ago, Stu said:

Aligning the Mount is fairly simple, but tonight it reset itself a couple of times whilst slewing. I’m wondering whether the power supply is not up to the job, I will check how much current it needs and then go from there. I’m fairly paranoid about ensuring the polarity is correct, not wanting to blow the Skysensor 2000PC controller up having looked for one for so long, so will be ultra cautious with any change.

I checked the manual, and I'm fairly sure that the problem was lack of supply from my PSU. I'm using a slightly silly approach, which is to plug the supply provided to me with the mount (which has the polarity reversed) into the cigarette lighter type socket on my main PSU. The most sensible course of action is to wire directly into my original supply which is 12V and 4A so should be up to the job. Slews are quite slow and I'm getting these resets which are annoying. At least though I've found out I can just press ESC and the original alignment is still valid which will save me some time.