[ATM] Secondary heater.

["Marco" <marco.miglionico@btinternet.com>]

I know i've been asking a lot of grinding questions and I will grind a large 
thin mirror some time,
but for now I've ordered my 20in F4.8 mirror with 3.5in flat. (will be ready 
before christmas).

How many Watts should I use on the back of the secondary?

I'll give you some of my conditions:

I'm in scotland. It can get down to -10deg C at night in sheltered places.
Also the humidity can be quite high  ~90%. Usually though when its very cold
it is not as humid. I've dewed up plenty of times with my 8.75in scope.

What about the Primary. Will the fans be o.k. by themselves?

any ideas about Wattage appreciated.

Marco. 

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