secondary mirror heating and attachment options

[troypiggo (Troy)]

I have a SkyWatcher Black Diamond 10" Newtonian. The secondary mirror on it is only 50mm diameter on the narrowest side. It appears to be connected to the "stalk" with double-sided tape, and the stalk is narrower than the mirror, so I can see the back of the mirror when I look through the end of the scope.

I was thinking that something like the Kendrick split dew heater would be perfect, but it appears too big - for 75mm secondaries? It has been suggested that I could do a bit of a DIY resistor solution on the back of the mirror part exposed, but just exploring all options.

I read here from their website that they don't recommend the wrap-around heater because the double-sided tape just acts as an insulator, but when I emailed them directly and asked, that was the system they recommended provided I put something around the heater to insulate it.

I'm a little concerned about heating the stalk and the glue on the double-sided tape letting go.

Would there be a better way for me to fix the secondary to the stalk to alleviate this problem? Will it even be a problem? What glues have you used that handle heat ok?

I know we're only talking about tiny amounts of heat, only a couple of degrees above ambient typically. Just thinking of some accidental scenario where the dew controller settings get bumped or something silly happens and a little more heat gets produced. Don't want the secondary falling off and onto the primary.

[troypiggo (Troy)]

Just heard from Jim at Kendrick again. He suggested taking the secondary off the stalk, removing the double-sided tape, gluing one of their standard elliptical heaters to the back, then gluing that to the stalk. Another solution, but similar issues and questions regarding the glue.

Thoughts?

[astronut (John)]

Hi Troy,
A member of MAS has a 12" version of your scope.
He also has a wrap around heater for the secondary, he has been using it for the last 12 months.
The only problem he has been faced with, is to keep the secondary warm enough to ward off the dew!!.
So I would recommend the wrap around heater, just be sure to insulate it from losing heat into the atmosphere.
An old thick sock is a low cost way!!
The other way is to exchange the secondary for one that is fitted into a holder, like the 10" & 12" Lightbridge.
This will work a lot better, but is an added expense.
Let me know if you are interested in this and I will send you pictures of my mod to my 12" Lightbridge.

Cheers, John.

[troypiggo (Troy)]

Thanks John. Got a few ideas now.

Regarding the glue, it's been recommended for me to use a neutral cure silicon. Think I'm all set.

[barx1963 (Malcolm)]

I use a Kendrick Wrap around heater on my secondary on the 12", had no probs whatever. Use a Digifire 7 controller and set it to the lowest setting, works like a charm.

[astronut (John)]

Troy,
One thing I forgot to mention, a shroud is a must.
Otherwise the heater is going to struggle to keep the sec dew free.

[troypiggo (Troy)]

Thanks again guys.

@John - my 10" isn't a truss it's a tube, making a shroud redundant?

[astronut (John)]

Sorry.................