Dew Controllers & Straps Questions

[Mav359]

I have an AstroZap dew controller and a strap for the C9.25 on it.

The other night whilst viewing i found that even with that on full power and the dew shield on the end of the scope after about 3 hours things started to mist up. I'm in my obs so i robbed the hairdryier and cleared off the dew but i expected the strap to keep the dew at bay.

1) Am i expecting too much? it had gotten to about -2

2) I have the strap just behind the scope apperture & secondry mirror is this the right place?

3) The strap never really gets hot, you can certainly hold it in your hand with full power on, should it be hotter?

As always i await the wisdom of the council

[malc-c]

I've juts purchased a couple of these, and when using it with my DC (non PMW) heater on full the band was comfortable in the hand. I've yet to see how it performs on the Mak127, finder and ST80 under real conditions

[perfrej]

I'd say you need a hood as well in order to get a hotter than the surround air column above the corrector plate. Mine doesn't get very warm either but the hood helps it do its job!

/per

[Merlin66]

Hmm

I have the AstroZap flexible dew shield and a 12" Dew heater band on my C11...and still find this problem.

Maybe it needs an additonal heater just inside the dew shield??

[Mav359]

Hmm

I have the AstroZap flexible dew shield and a 12" Dew heater band on my C11...and still find this problem.

Maybe it needs an additonal heater just inside the dew shield??

I'm going to move my dew shield in front of the secondary mirror in an attempt to stop the cold air reaching the secondary mirror and see what happens, failing that MORE MORE MORE!!!!