Dew Control

[bluescope]

Ok

So now I've got a nice Apo what's the best way to deal with dew on the lens ..... Kendick Heater ? hair dryer ? other brands ? other devices ?

Suggestions please !

:thumbsup:

[rogerg]

I purchased a set of dew heaters and controller from Astro-Optical (http://www.astro-optical.com.au) to use on my Megrez & camera lenses. Works great and costs less than Kendrick. They draw max 1 amp each, but the controller has variable dial to tune their heat, I sit them about half power. Plug into cigaret lighter socket. Highly recommended.

Roger.

[bluescope]

What did the whole setup cost Roger and what did it include, if you don't mind my asking ?

:thumbsup:

[rogerg]

Had a feeling you were going to test my memory on that :)

I have 2 x dew straps to suit up to 100mm diameter tube, plus 1 x control box which has 3 ports on it and a temperature/power dial.

I have a feeling the whole setup was about AU$140, but that's just a vague memory, I really cannot be sure sorry.

Roger.

[bluescope]

That doesn't sound too bad at all compared to Kendrick and Orion.

I had a quick look at the website link and could only find the straps and no prices.

[rogerg]

Ahh.. it was some time ago (something like a year). I remember ringing them up and asking about it, I don't think they had prices on their website then, otherwise I would've probably just ordered them online. They were very helpful on the phone.

Roger.

[erick]

Steve, check the Thousand Oaks controller and DewNot heater straps from Peter Read:-

http://www.sdmtelescopes.com.au/shop/index.php?cPath=27&osCsid=400be140dd4377444f2a579bf422 3469

I'm happy with them.

[bluescope]

Thanks Eric, I'll check it out.

[gmbfilter]

I bought the orion 4 pot dew heater works as advertised but I don't like how stiff it is to push the RCA (i think that's what they are called) plugs in and out. I would liked to have try the TO controller.

Mind you they don't fall out!

[JethroB76]

Was going to suggest what Eric did, especially the dewnot gear, however the controller can be made up from a kit if you're that way inclined. I made a couple last year for about $20 each, there are examples in the IIS projects area..

[bluescope]

No worries, thanks Roger.

:thumbsup:

[bluescope]

Cheers !



Not that way inclined Jethro !

[bluescope]

I see Kendrick have a new ccompact system


http://www.kendrickastro.com/astro/dewremover.html#FireLiteController

Has anyone had any hands on experience of these ?

:thumbsup:

[montewilson]

I made mine too with Nichrome wire from Jaycar. I just leave them on all the time with a gentle heat. I haven't had dew on my coke bottle for more than ten years and it cost me less than $5.

[bluescope]

What did you use to cover the wire Monte and how do you control temp ? Any pics ?

[AlexN]

I got the Thousand Oaks controller from Peter Read with a 3" band for my 80mm, a 4" band for the 90mm, a 2" for the reticule EP.. all up it set me back $260... Bargain in my opinion.. works brilliantly.

[bluescope]

Thanks again Eric, looks like the go. I have emailed them regarding suitable size strap for FLT110.

:thumbsup:

p.s. Thanks also Alex !

:thumbsup:

[erick]

M sense is the straps are "oversize" - they overlap several cm in all my applications - which is fine. With the velcro connection on an elasticated band they are so easy to position and fasten.

[Paramount]

Hi
I use a Kendrick Digifire 7 and am very happy with it, you can adjust the output from 10 to 100% depending on aperture and ambient temperature and there are 4 variable outputs plus a dedicated 12v output. I would be very cautious about using hair driers or equivalent as the heating elements attract dust and when you switch on there is a risk that you then blow dust all over your valuable optics (not a good idea), if you are going to use a hair drier and I have in the past aim it at the side of the telescope close to where the objective lens is and at an angle pointing towards where the light comes into the telescope, that way you won't risk blowing directly at the lens
Best wishes
Gordon

[bluescope]

Cheers Eric

I noted that on the site they were out of 4 inch straps so I'll see what they say. No reply yet !

:thumbsup:



Hi Gordon

No worries ... I didn't want to use a hair dryer hence my posting of this thread but thanks for the tip if the need ever arises.

The Thousand Oaks controller also has 4 connectors and an auxiliary 12v output and is fully adjustable from 0-100% and is about AUD$70 cheaper that the DigiFire 7 so I think I will go with it and the Dew Not straps. Also Kendrick recommend using their Premium Controller and straps if temps get close to 0 degrees in your location or if you get very heavy dew ( their Premium gear is a lot more expensive ). I am moving to a 5 acre dark sky location early next year that is about 100kms inland and gets quite a bit colder in winter than Perth which is on the coast ( not sure about dew levels ) but I really don't want to be spending AUD$600-700 for dew control unless I absolutely have to.

Hope you are getting some clear skies in UK ... I'm from Rugby in Warwickshire originally 42 years ago so I know how fickle the weather can be.

Thanks again.

:thumbsup:

[Paramount]

Hi Steve
I used to use a Premier controller but had continual problems with it cutting out whenever there was a slight variation in voltage and I also found it over complicated and the menu system a nightmare to use, since changing to the digifire 7 I have not had any problems at all, I use it with an AWR 240v AC to 12v DC transformer and it works fine.
Weather wise we have had the wettest August on record and September has started with floods in many areas so I have to grab whatever imaging time when I can but at least I am getting some results as you may see from my postings.
Best wishes
Gordon
:rain:

[ausastronomer]

Come on Monte tell the truth, it's actually the exhaust heat off your generator that's keeping the dew at bay. I saw you aiming that exhaust port straight at the objective of your Tak when you set it all up. Your dew heater is just for show :D

Cheers,
John B

[ausastronomer]

Hi Gordon,

I also have a Kendrick Digifire 7 fitted to my 18" Obsession. I am sure it is an excellent controller when fed through through a mains supply transformer. Using battery power it certainly has low voltage issues. The low voltage warning light comes on every time the servocat drives are engaged with a fast goto slew and when battery power has dropped a bit, using the servocat drives causes it to cut out completely.

For this very reason Peter Read at SDM Telescopes switched from the Kendrick Digifire systems (7 and 10) to the Thousand Oaks system. The big advantage of the Thousand Oaks controller is that you can disable the low voltage warning light and cutout. The dew heater straps work perfectly when fed a voltage slightly less than 11.8V, which is where the Digifire cutout engages.

I am about to purchase a Thousand Oaks controller to avoid the low voltage issues of the Digifire 7.

Cheers,
John B

[bluescope]

Thanks guys for the input to this thread, I have now ordered the Thousand Oaks controller and DewNot straps from Peter Read and they are being put in the mail tomorrow ( Friday 12th ).

Looking forward to no more dew problems on the FLT110 and being able to image/observe all night long if and whenever I feel like it.

Cheers

:thumbsup:

[erick]

Presuming your battery doesn't run flat! :P

[RB]

I've been using a 'Dew Buster' http://www.dewbuster.com/ which I bought second hand off a member here and am very happy with it, but not sure if they're still available.
I like this unit because it has an external temp sensor that 'follows' the ambient temp and adjusts itself accordingly.

The Thousand Oaks controller sounds like a great unit and if I am to get another controller I'll be seriously looking at the Thousand Oaks.

[erick]

Andrew, my reading says the DewBuster has more desirable capability than the Thousand Oaks - namely the sensor control of three AUTO outlets. I understand that the five AUX outlets are also not so fixed, switching from medium power to full power if the scope temperature differential is high. Also the unit will reduce power consumption if it detects low battery, reducing to zero consumption when the battery hits 10.5 V (at which stage I don't think you'll start your car?)

However, I'm not sure where to plug in an intelligent heater such as the Astrosystems secondary mirror heater. Probably have to power directly from the battery.

I think you have the Rolls Royce unit already!

[RB]

Yes indeed Eric I am very happy with this unit, it has performed flawlessly for me and having 8 outputs total and the external sensor is fantastic.

I only mentioned that I'd consider the Thousand Oaks because I initially did a search the other day to find the unit on OPT Corp but they were not on there, and I heard the guy that makes them was affected by the hurricane and had stopped production.
But according to the web site it now seems he is selling them direct so they should be available again.

:)

[bluescope]

I'll be using mains power Eric so no problem in that department. I also have a 17 amp-hour jump starter ... but that's more for starting my car if my battery goes flat when I move to the bush as I will be 12kms from nearest town. When I setup my observatory there it will all run on mains supply again as it does here.

:thumbsup:

[ausastronomer]

Hi Erick,

I have the Astrosystems Secondary heater fitted to my 18" Obsession as well as the Digifire 7 Dew Heater Controller.

Irrespective of which electronic dew control system you use, it is necessary to power the Astrosystems secondary heater system with a "non controlled" 12V power supply. The Astrosystems secondary heater has automatic temperature sensing which is adjustable with a trimpot on the circuit board. You do have to totally remove and dissassemble the secondary mirror and holder to get to it. The Digifire 7 has 2 dedicated "non controlled" 12V power outlets which are suitable; and the Thousand Oaks controller has one. Dedicated 12V outlets are an optional extra on the "Dewbuster" system. I have the UCA assembly "powered" on my Obsession and just feed the Astrosystems Secondary Heater from +ve and -ve power posts on the UCA. I don't use the power outlets on the Digifire 7 at all. I get the power to the Astrosystems secondary heater by using one of the spider vanes as the -ve power feed and use a thin wire superglued to the top of another spider vane as the +ve power feed.

Cheers,
John B

[bluescope]

My Thousand Oaks controller and DewNot straps arrived today ... they look like good gear but with the weather like it is in Perth right now it's going to be a few days before I can try them out.

:thumbsup:

[AlexN]

Good going Steve! :)

I was saying the other night, even the finest apo ever built would be useless if it were not for dew heaters.

[bluescope]

Too true Alex ! I'll probably get a strap for my 180mm Pro Mak as well one day.

:thumbsup:

[AlexN]

mmmm that reminds me I must get one for the C11... Im thinking that hairdryer might be a better option for a corrector plate that big... although, provided you have the dew heater on BEFORE dew becomes starts forming, it only requires a little heat to keep the corrector warm enough... If you put the heater on after dew has formed, it requires a lot more heat to actively remove the dew.... Keep that in mind.

[bluescope]

The heater will be on as a standard part of setup in my case ! You should get one for your 11" they're not that expensive.

:thumbsup:

[qld]

hi team, have any of you tried a cheaper method?
i have an electric blanket that operates on 12volts
which i put over the scope( newt ,maks schmidts refractors).these cost $15.00 from Auto one and used sparingly your 12v battery lasts throught the night,and also doubles up as a genuine blanket when camping out or
asleep in the back seat.They are similiar in design to the normal auto rug/blanket except for the 12v cigarette plug/cord.they work well on truss dobs,particularly if you get a black one as it makes a very good shroud using a strip of velcro top and botom to hold it in place, this consultation was free, and for the affectionardos no global warming contribution ,all warming is limited and usefull.:rofl::lol::whistle:

[AlexN]

yeah that would be a fair bit of weight hanging off the mount man...

[RB]

Never on a scope since you can't regulate the heat and also it's too heavy, but I have used the 12v electric blanket, plugged into my 240V 'hotbox inverter' (http://www.iceinspace.com.au/forum/showthread.php?t=8150&highlight=hot+seat), stretched out across my accessories table to keep dew of my gear.
I leave it on all night sometimes.

[qld]

hi team the blanket is very light and does not pose a balancing problem,i only turn it on for a little while to clear away the mist.my one is made by AUNGER CARCRAFT PTY LTD of 320 Fison Av East Eagle Farm Brisbane
Qld., email www.aunger.com.au (http://www.aunger.com.au) you can also control it through a dew controller qld:)