Are all dew heater controllers equal, or are some more equal than others?

[Feral Rabbit]

I am fed up with the dew stopping my sessions and even with a dew shield (unheated) my primary optic is misting up within a couple of hours. I have decided to get a heated dew shield to begin with and see how I go.

As always with astronomy equipment it's never as straight forward as just buying one thing and always with astronomy it's never cheap but I was wondering if all dew heaters are the same (obviously they are used to control temperature in the strap/shield) in as much as drawing the same current if set at the same setting.

I am looking at

The Kendrick

The HitecAstro

The Astrozap

I will probably get a heated dew shield although there are many of these on the market too and I may as well ask the same about these whilst I'm at it and see how it goes but may end up with getting a strap for the RDF too.

The Kendrick is £40 more than the other two but is it really £40 better?

Thanks in anticipation for the advice I know you guys will steer me in the right direction

[Davey-T]

Lot's of folks make their own, have a look through the DIY forum.

Dave

[Liquid360]

Kendrick makes great stuff, but apparently the owner has recently been diagnosed with cancer and they're closing down for awhile. I'm still trying to get equipment I'd ordered.

[Tim]

Ive used astrozap heated dewshields on both of my scts and a mak newt. they make a real difference

my only very slight critiscism is that the stitching can weaken the seam and if you are a bit heavy handed when (if) you roll them up you can slightly crack them.

Its tbe kind of thing you do once I plug them in to the astrozap dual channel heater

[baggywrinkle]

I have the Hitec 4 channel and the strap for a 9.25 SCT along with the separate dew shield.

The strap works really well. I am ordering two more, one for the 2'' finder and a 5'' one for my ST120.

I have not used the others so I cannot offer an opinion.

[IanL]

I made my own straps and controller box, so I can't comment on the quality of the commercial offerings.  Would be surprised if there was much of a difference in the internals so if you aren't willing/able to go down the DIY route just get whichever looks to be best value for money.  Given the cost of the components the markup of the commercial offerings has always been a bit eye-watering, but I guess it is a small-ish market so overheads may come in to it somehwere.

I and many others use low voltage LED dimmers for the controllers, which can be had off fleaBay for £3-£5 delivered (the cheaper price if you are willing to wait a week or two for them to come from China-based sellers, otherwise a bit more for the same thing from the UK).  MIne have lasted two seasons with no problems, but they're so cheap they are effectively disposable items anyway.  The heater bands can be made from Nichrome wire which can be bought for a few quid off fleaBay, plus duct-tape for the housing.  An hour or two with the soldering iron plus a few quid of plugs/connectors from Maplin and you're done.  Have a look in the DIY forum if you'r e interested.

[Earl]

I have several Hi-Tec products and i like the fact that theirs offers 2 x 12v outputs also.

[Feral Rabbit]

Yes unfortunately my DIY skills don't go much beyond wiring a plug or changing a light bulb I'm afraid so I will have to play safe and go the shop bought route.

I was just wondering if the draw of power is the same for all these dew heater controllers or whether some are better at conserving power although as I have a Celestron the HitecAstro has piqued my interest as it comes with a through port for powering the AVX, so less wires to worry about.

Thanks for all your help and input.

[Northern Soul man]

Hi Martin, a really good question you've asked on here.  I use the HitecAstro 4 channel dew controller with the Astrozap combined dew shield and heater - a very nice piece of equipment - but as said quite expensive - but you have the added bonus of the jack that supplies power so that you can connect the scope to it (I have the CPC 1100) directly - never had a problem with it and it cuts down on the amount of cables - the controller has a variable power knob for the four outputs - so I just connect the dew shield, put on full power, connect the scope and away I go!!! I think the larger apertures need the full output of the controller (I think its around 4-5 amps) as this incorporates the whole circumference of the larger apertures and I think the max power is for around the 14" aperture - I think that the dew shield on its own will be good for most of the nights - but some really "wet" nights will need the added heat - don't get me wrong - its only just enough heat as to keep the front clear without the introduction of "too" much heat.  I have used a 17ah Maplins power tank for the last couple of years and have been pleased with the set up - your good for 2 - 3 hours and probably more - but I always charge the powertank after use and leave it connected continuously with a motorbike charger/optimiser for the best results - not a good idea to leave these lead acid batteries "uncharged" for long periods, they benefit with a charge that's "topped up" all the time.

Paul.

[Feral Rabbit]

Thanks for the help guys. I have decided to go with the HitecAstro 4 controller and the Astrozap heated dew shield.

Paul would you happen to know what the type of power lead I need to connect the Hitec to the AVX mount and where I can get one please? (I assume it's the same as those on the CPC mount)

Regards

Martin

 

[Northern Soul man]

http://www.nexstarsite.com/OddsNEnds/PowerSources.htm

Hi Martin, nice 1 - here's the link for the power lead size - I think its the same for the majority of the Celestron Mounts - but I can't find any details for the AVX, I think that it may be the same - as the majority of the mounts are covered - its a 2.1mm centre positive with - I think - an outside diameter of 5.5mm (which you need on both ends of your power lead to fit the controller end and the mount end).

I made my lead up myself, I cut up an old lead which had a cigarette lighter attachment on the one end and the adaptor (2.1mm inside diam) on the other, just checked that I soldered the wires the correct way round (centre tip positive(red), covered the joint with shrink wrap, as I mount the dew controller to the fork arm nearest the input for the power on the mount - I only needed a short lead.

I've been trying to find the info on the AVX mount, but I can't seem to find anything regarding a power lead size - the above link gives details on nearly all the other mounts - but can't be certain, so you could post a topic on the Mount section on here for details of which lead you need to fit your mount.  I've looked, but can only find the cigarette lead type on the usual sites.

Hope that helps a little.

Paul.

EDIT - http://www.maplin.co.uk/p/maplin-21-x-55-long-dc-power-plug-hh61r

Found these think they are the correct dimensions - see if anyone chips in with some more advice.

[Feral Rabbit]

 Thanks for taking the time to find and reply with the info Paul. I may take the HitecAstro and the power cord from my AVX into an electronics shop and see if I can get one made up with the right plugs. My DIY is really quite abysmal and I'd hate to damage my pride and joy.