Now that I have built my Dew heaters, and they are working well, I though about the problem of the Dew heaters getting cold and wet in the first place. Lots of heat from Dew Heaters just wafts off externally into space!
We can apply all sorts of heat the the lenses, use dew shields to keep dew and light away, but what if we could stop the dew heaters from dissapating heat externally, and trap it all internally.
That would make them more efficient.
So, the trick is to stop the dew shields from getting cold and wet. Dew shields act like a big HeatSink robbing heat from the heaters.
Solution - Make the dew shield and Dew Heater some Pyjamas!!!
This will keep the Aluminium on the ED80 and the Plastic on the 100mm guidescope from getting as cold (less dissapation), AND trap heat inside where it's needed.
I hunted around in my shed (sheds are handy aren't they) for something to make the pyjamas out of.
To cut a long story short, I ended up wrapping both heater strap areas and dew shields in old style woollen underfelt (used in upholstery), and covered the whole lot in Balck vinyl.
It's like little sleeping bags
The vinyl I used is from one of those vinyl clipboards. I cut the end open and took out the stiff cardboard. The tube made from the vinyl fits exactly over the underfelt
That should stop the 'Heatsink' effect
Pic: Telescope Pyjamas (or sleeping bags)
Notice I also Velcro'd the wiring out of the way
