Dew heater for 8" SCT, ST80, and finderscope too I guess

[Pharian]

If anyone has a cheap dew heater for 8" SCT, ST80, and finderscope too I guess then I would be interested in nabbing them. Dew is my new nemesis, it is all I can do to stop myself wiping it off the front of the OTA (which I know is a big no-no). Grrr!

[iborg]

Hi

I don't have a spare, but, take a look at this link for (I think) a good home made one.
http://www.iceinspace.com.au/63-597-0-0-1-0.html

I use a motor speed controller kit (Jaycay/Altronics) and about 12 pairs of paralleled 2ohm resistors. Velcros nicely into the area at the front of the corrector where the cap goes.

I bought a pile of the resistors cheaply from ebay. If you decide to do something similar, I would be happy to sell you left over resistors at cost plus postage.

Philip

[Pharian]

Hi Philip,

Thanks for the response, my apologies for my delay in answering.

That home made one you built sounds interesting. Any chance I could please trouble you for some photos of where you mount it on your scope please? I'm new to this and not sure exactly what area I need to build it to fit.

Thanks again,

Chris

[jenchris]

Take one old hair dryer.
Remove heater coil.
Straighten out a few feet and use an ohmeyer to give you a couple of amps worth of ohms (v=IR).
Test temp of section when 12 volts is placed across it.
Should be just hot enough to hold onto without screaming.
Place wire inside some silicone sheathing.Wrap around ota near objective .
Cost = about 3 dollars for an old hair dryer.

[iborg]

Hi Chris

The photo called Velcro show a bit of the velcro in the area I mentioned.

Heater is the finished heater 'strap', looks rather like a length of wire.

Fitted shows the heater in place.

Of course, being black on black makes it so easy to see!

The hair dryer idea should also work. I do suggest using a variable voltage supply, particularly if you are running from a battery. You can then reduce the amount of power the heater is using to keep the dew off.

I have a cheap temp/humidity sensor from ebay that I keep on eye on. When humidity goes over about 80%, I use the heater. I normally leave the sensor inside the dew shield to have an idea of conditions in there.

I read somewhere about putting it in this area. Seemed to make more sense to me than heating the whole front end of the scope.

Philip

[04Stefan07]

I am selling this finderscope if you are interested.

http://www.iceinspace.com.au/forum/showthread.php?t=153991

[Pharian]

Fantastic, thanks Phillip. Much appreciated. That looks like exactly the business. Cheers.

My apologies Stefan, I meant a dew heater for a finderscope, not a finderscope itself.