QHY8 frost

[martin_h]

After having some problems with misting/frosting of my CCD I decided to make a heater for the nose of the cam.

The nose is only about 10mm deep so a comercial dew strap wont fit, being about an inch wide. After some research on the WWW I found that most home made heaters involve wire wound resistors or nichrome wire, the resistors are too big to fit and the wire option was impractical being as its only going round a 55mm nose piece.

So I chose the standard 0.6W resistors for 2 reasons - 1. They fit. 2. I had some!

Construction was straight forward, work out the circumference of the nose and cut some single strand tinned copper wire to fit, solder the resistors ladder fashion along the length, add a lead and plug.

I wrapped the ladder in gaffa tape to insulate it. Wound the lot round the nose and held it in place with a velcro strap, plugged it in to my Astrozap Dual Channel Dew Heater Controller and fired it up.

It seems to work ok on a minimal setting, I wouldnt want to run it at full tilt because it gets HOT!