Anyone use the Kendrick primary mirror dew heater?

[UlteriorModem]

https://www.kendrickastro.com/newtonian.html

I am considering getting one of the primary mirror dew heaters from Kendrick.

Was just wondering if anyone here has one or has used one.

My main question is about the mounting. As I understand it it basically glues onto the backside of the mirror with some silicone.

But what about putting it back in the mirror cell? Is any modification required to accommodate the wiring? Will it end up 'tilting' the mirror? Is it slightly smaller than the mirror (8 inch) ?

Thanks!

[UlteriorModem]

Well I guess I will be the first one

Just ordered it. Will update when it arrives and I get it installed.

[Lady Fraktor]

I doubt you will have any issues installing it UM, Kendrick has been making them for years and I have never read any complaints about these.

[yobbo89]

I have a kendrick heater controller, they don't make a heater to match my scope so I'm going to make my own heater strip, mainly for the secondary.

You have to glue those elements down. Kendrick should also sell Velcro wrap around heaters for the actual primary mirror aswell and wrap around for the ota tube incase you can't access or fit a heater directly on the rear .

I ditched the idea of heating the rear, it dosn't realy get much dew on the primary plus I'm cautious about the heat effecting my images and focusing.

[UlteriorModem]

I have a kendrick heater controller, they don't make a heater to match my scope so I'm going to make my own heater strip, mainly for the secondary.

You have to glue those elements down. Kendrick should also sell Velcro wrap around heaters for the actual primary mirror aswell and wrap around for the ota tube incase you can't access or fit a heater directly on the rear .

I ditched the idea of heating the rear, it dosn't realy get much dew on the primary plus I'm cautious about the heat effecting my images and focusing.

Kendric actually discusses this. They say they dont believe in them.

We do not recommend using heaters that would wrap around the outside of the optic as the thickness of Newtonian primary mirrors make this method ineffective due to the mirror mass

Already have the Kendric controller although it is branded differently if you open it up you will see Kendrick silk screened on the pc board

[yobbo89]

My mistake, it was recommended to do this for my type of mirror,more or so tuck the wrap underneath I guess, it's a little different on the backside to most mirrors.

[Lady Fraktor]

Is that a Royce mirror yobbo?

[yobbo89]

Is that a Royce mirror yobbo?

No, I did check out royce mirrors, they do make "conical mirrors" , and a normal mirror is called a continuous faced mirror?

This is a rebranded scope of a gso truss tube, manufacture of the glass I don't know.

[Lady Fraktor]

Interesting I did not know GSO had copied the mirror.
Royce made some outstanding optics while they were in business.

[UlteriorModem]

My mistake, it was recommended to do this for my type of mirror,more or so tuck the wrap underneath I guess, it's a little different on the backside to most mirrors.

Yea I would say that is ... unique!

How the hell is such a thing mounted?

[Lady Fraktor]

These can be used with conical mirrors as well as regular ones.
https://www.astrogoods.com/cells.shtml

They can also be mounted like this for a clipless setup.
http://www.rfroyce.com/conical/mount%20CFB.htm

[yobbo89]

My mistake, it was recommended to do this for my type of mirror,more or so tuck the wrap underneath I guess, it's a little different on the backside to most mirrors.

Yea I would say that is ... unique!

How the hell is such a thing mounted?

Pretty sure this mirror is just glued onto a plate, I pulled this image from another imager on google who has my scope, it's been awhile since I've pulled my scope apart for cleaning, so I don't recall.. Some strong epoxy!

[DeanD]

Celestron used to have a mirror like that on their 8" dobs (15 or 20 years ago). It was held by silicon in the centre.

They were quite a nice scope with a few innovations that set them apart from the Meades and others at the time.

- Dean

[UlteriorModem]

The primary mirror heater arrived today. I unboxed it and looked at it. Seems fine. Although it came with a 'heavy' cable attached not sure how that will work with the mirror cell. Also it seems a little short. Frankly I wish it had come with just some wire leads and I could make up my own cable. We will see.

Will not get a chance for a day or two to install it as I plan on doing some imaging tonight and the silicone needs like 24 hours to cure. I'd rather do some imaging than waiting on glue to cure. Who knows after tonight it may be another two week hiatus. Plenty of time for glue to cure

But when I do I will get some pics of the install.

[UlteriorModem]

Okay as promised here are some pics of the initial install.

I will have to mod the mirror cell to allow the cabling to exit. But that will come later.

20201114_083856 by Tom Whit, on Flickr

Here is pretty much everything you will need. The heater is still in the box. Some silicone glue. The 'bolt case' is my cleaning stuff. It has a large microfiber cloth in it. More on that coming up.

20201114_083929 by Tom Whit, on Flickr

Pretty much the same shot with the heater out of the box and the short instruction sheet. Pretty much says 'glue it on'.

20201114_084018 by Tom Whit, on Flickr

Took the large microfiber cloth and spread it out carefully.

20201114_084504 by Tom Whit, on Flickr

Remove the mirror from the cell and place it ever so gently face down on the microfiber cloth. Cleaned the backside with some alcohol note the dirty paper towel. The card is for spreading the glue on the backside of the mirror. Might want to put on some gloves. Silicone can be messy and to some people an irritant.

20201114_085422 by Tom Whit, on Flickr

After spreading a thin layer of silicone just place and center the heater. Easy.

20201114_085752 by Tom Whit, on Flickr

Then flip the mirror over so that the weight of the mirror will help the heater bond to the backside.

20201114_085814 by Tom Whit, on Flickr

I put the microfibre cloth over the mirror to protect it from direct sun. Now I just have to leave it sit for 12 hours or so

Next I will start figuring out how to mod the cell!

[Lady Fraktor]

Very nice UM, I am sure it will work very well for you.
If you need to extend the cable you can purchase RCA F-M cables in lengths from 2'-25' long.

[yobbo89]

ahh kendrick website says that rca cables are to thin for the current to be used, they need thicker gauge, i'm sure you could make some up and buy some rca ends to soldier to.

[Lady Fraktor]

I have been using them for years this way without issue.
Mind I do not buy thread thin RCA cables either.

[UlteriorModem]

ahh kendrick website says that rca cables are to thin for the current to be used, they need thicker gauge, i'm sure you could make some up and buy some rca ends to soldier to.

Wow really? Thing only has a Max load of 10 watts, thats less than 1 amp ??? I don't get that statement at all!


I looked at the mirror cell and the mirror fit later today. It seems like no mods will be necessary. I did not assemble it because still waiting on the silicone to cure.

[yobbo89]

proprietary