Re: Saturn 2005-10-17


"zAz (Dan)" <zaziork[NOSPAM]@[NOSPAM]hotmail.com> wrote in message
news:16GdnQ_HtMeHsMjenZ2dnUVZ8qadnZ2d@xxxxxxxxxxxx
>
> "adm" wrote:
>
>> Cool down time isn't really an issue for me as I work from home, so can
>> set up in the afternoon and then leave it all to cool down sufficiently
>> (so sufficiently that by the time I get to use it, it's covered in dew.
>> But that's another story and one that is now fixed !).
>
> Hi alasdair,
>
> Forgive me for butting in, but... may I ask how you fixed the dew problem?
> I get similar issues with my 8" newtonian, so much so that I end up
> trading off cooling down time for dew-free time! I've heard a hairdryer is
> a good option, but I've yet to risk the attendant electric shocks with
> that one!

Hi Dan,

I fixed it by spending money ! Dewbuster heater controller bought from
OPTCorp (50% of the cost of an equivalent specced controller from UK
dealers) and a couple of Kendrick heater strips - one for the Corrector
plate and one for the finder objective.

I also made a dew shield from a closed cell foam camping mat, which worked
well but had problems staying in a perfectly circular cross section, so in
the end I had a local machine shop roll me an aluminium tube 300mm internal
diameter by 750mm length. This cost the pricely sum of £20 - although I
haven't painted it yet so it will probably end up costing around £30 or so -
but then it is equivalent to the £150 Meade OEM articles.

Anyway - between these two, my dew problems are now gone completely. (I
could maybe use a couple more heater strips - one for the finder eyepiece
and one for the telescope eyepiece, but these are really more luxury than
necessity.) The water can be literally running off the scope tube and the
optics stay nice and dry.

Next step is to build a nichrome heater element that will actually fit
inside the corrector plate mounting itself and do the same job, but look
nicer.....

Oh yes - one other point. I did find that the scope and dew heaters kind of
ate through the battery power (I just had a crappy Halfords 12V power pack)
so in the end I bought a 10Amp 240V - 12V power supply and a multiple "car
fag lighter" socket adaptor and then ran 240V out to where I set my scope
up. That fixed the dead battery halfway through the night syndrome for good.


.

Relevant Pages

  • Re: Eyepiece heater question
    ... It is important to let your scope temperature ... I find they don't dew up unless I ... Simply resting a lens cap on the eyepiece or taking the ... I doubt the dew heater would be of any use on dob or newtonian. ...
    (sci.astro.amateur)
  • Eyepiece heater question
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  • Re: Eyepiece heater question
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  • dew device (with pictures)
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