Dew heater wattage

[JohnP]

Mine is like Robert's - I struggle to detect it's even on.......

[The Thing]

I have a Kendrick DigiFire 10 dew heater controller. It comes with a temperature sensor that velcros inside the AstroZap dew shield (which has the heater built in). You can set the number of degrees to keep the air above the corrector plate at (I have an SCT).

Usually I have it set to be 1 degree above ambient on about 70% power. I use 2 degrees very occasionally - but I am usually inside if it's that damp out.

Also I find it pays to have the dew heaters on an hour before I want to use the scope so that everything stabilises, initially the SCT dew heater can draw a lot of current as it heats the metal ring holding the corrector plate.

I also heat the 2" diagonal and the guide scope with home made wire based elements and the Telrad has a couple of resistors under the glass.