Dew heaters

[Hawkeye]

Hi All,

I am sure this is a question that has been asked before but.....

Where is the best place to put a dew heater on a SW200P reflector to prevent the secondary mirror dewing up ?

By the way I was looking to build my own heater strips as the ready made ones seem very expensive for what they are!

Cheers
Paul

[Oily]

I put my 'DIY' heater around the mounting of the secondary,the heat transmits through to the mirror.

[NGC 1502]

Hi Paul.  This link http://www.kendrickastro.com/astro/newtonian.html has details of different types of secondary heater (scroll down).

You could perhaps copy the design for your DIY version.

Regards, Ed.

[Hawkeye]

Thanks for the replies, looks like I have a little project for the next few days now.

Sent from my Nexus 7 using Tapatalk

[glappkaeft]

Hi All,

I am sure this is a question that has been asked before but.....

Where is the best place to put a dew heater on a SW200P reflector to prevent the secondary mirror dewing up ?

Have you tried a dew shield? Usually that is sufficient for Newtons.

[SW130p]

I made a long dew shield out of thin black foam from craft shops for my SW130p, been out in fairly damp nights with good results, no dew on the secondary, the tube was covered in dew so must be working. I did noticed that the RDF did start to mist up so I made a shield for that too which helped keep it clear. Now I have added a 6 resistor heater to the shield which has been brilliant.

I'm thinking off making a heater for the secondary too but a bit worried as how the mirrror is attatched to the stem. Is it glued? if so won't the heat soften the glue and cause the mirror to fall and damage the primary?