Cheap Dew Straps

[Garbz (Chris)]

Hi all. Anyone have an idea where I can get a relatively cheap dewstrap from? I have this aversion to paying $65 for a $5 piece of carbon deposit sitting between two sheets of $0.50 plastic, sewn into $1 worth of material, connected with $0.20 worth of cable, with a $0.50 connector on the end.

Oh and then paying shipping on top of that too. Are there any reasonably priced dew straps out there or do I need to continue making my own? Hopefully before astrofest.

[RickS (Rick)]

Chris,

You should be grateful that the manufacturers of dew straps haven't yet adopted Intel sized margins for making money out of sand

Peter Tan usually has some fairly sharp pricing: http://www.tan14.com/ Might still be expensive compared to roll your own.

Cheers,
Rick.

[malau (David)]

Originally Posted by RickS

Chris,

You should be grateful that the manufacturers of dew straps haven't yet adopted Intel sized margins for making money out of sand

Peter Tan usually has some fairly sharp pricing: http://www.tan14.com/ Might still be expensive compared to roll your own.

Cheers,
Rick.

If I knew it few months ago I may go to there and have a look

[Garbz (Chris)]

Thanks Rick, that's about the same price I can get Dew Straps for from ebay. It's ludicrous. At least Intel have R&D, the R&D for designing a dew strap can be completed in about 7 minutes including a toilet break.

[Allan_L (Allan)]

I thought about trying one of those heater straps they use in home brewing kits.
About $25.
But they are designed to run off 240v AC.
Not sure if they can be converted successfully for use on 12v DC?
Any ideas?

[Garbz (Chris)]

Unlikely. Most dew heaters are extremely basic devices. A little resistive device in simply burns power to heat, usually made of a carbon strip or a nichrome wire. It doesn't draw a constant current so the only way to get the rated heat out of it would be to give it the rated voltage or to modify the elements themselves, at which point you could just make your own.

[glend (Glen)]

I tried making my own dew staps (using 330 Ohm resistors in a ladder configuration), and while they worked, they were a mess in terms of the joints to manage and breaks due to flex. Trying to get them to look reasonable was a problem as well because I can't sew and heat shrink tube was just hiding potential problems when a joint broke. It comes down to what is your time worth to you and do you have the tools and skills to make them.

I decided that the Dew Not straps were a pretty reasonable investment, and I bought three from Agena Astro:

http://agenaastro.com/dew-not-dew-remover.html

No problem with these and they output enough heat for Australian conditions. I would problably go with the Kendrick Premier heaters if I lived where below freezing temps were the norm.

[OICURMT]

Originally Posted by OICURMT! (From a different astronomy forum...)

Sky & Telescope had a DIY article back in about 2004-2005 (can't remember the exact year). Simple explanation of how it works. People are moving to nichrome wire with end resistors, but a resistor only based one is still a good way to go.

Everybody's Do-It-Yourself Dew Heater - Do It Yourself - SkyandTelescope.com

FYI Can't get cheaper than this...