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Secondary dew heater

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#1 Brett Carlson

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Posted 15 February 2013 - 10:30 PM

I'm looking at making a homemade version of a kendrick split ring dew heater. I was going to use nichrome wire as the heating element zig zagged around some kind of flexible material.

My question is can anyone suggest a material? It obviously would need to non-conductive but also able to transmit the heat from the coil to the secondary. How about the backing? Neoprene foam?

What materials do the Kendrick heaters use?

Thanks for any help!

#2 GlennLeDrew

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Posted 16 February 2013 - 12:08 AM

You could simply epoxy a 1 Watt rated resistor of about 150 Ohms (1 Watt) to 300 Ohms (1/2 Watt.) Or 'spread the love' by using two 1/2 Watt rated resistors in series, each having one-half the resistance for a singleton.

#3 Brett Carlson

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Posted 16 February 2013 - 07:39 AM

The material I'm looking for isn't the heater element....it's the material to sandwich the nichrome wire. Something flexible....I think I'm going to pick up some sheets of duct tape and try that.

#4 Achernar

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Posted 16 February 2013 - 09:26 AM

Try heat shrink tubing, I use that aboard ship to seal connectors on boxes. It can be found with glue on the inside, or without. Either way, the right size will form a tight fitting skin of insulation around the nichrome wire. You can also find at Lowes what amounts to liquid electrical tape, but that is messy and best used with ventilation.

Taras

#5 Mirzam

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Posted 16 February 2013 - 09:58 AM

You will have better results if you can insulate the back of the secondary. Otherwise you are mainly heating air.

The ideal solution is a shroud, but if you have a secondary that is glued to a stalk I would suggest some sort of thick rubber (1/4") or foam insulation covering the heating element.

JimC

#6 Brett Carlson

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Posted 16 February 2013 - 02:54 PM

You will have better results if you can insulate the back of the secondary. Otherwise you are mainly heating air.

The ideal solution is a shroud, but if you have a secondary that is glued to a stalk I would suggest some sort of thick rubber (1/4") or foam insulation covering the heating element.

JimC


I have black foam to insulate the back of the dew heater for the secondary ready to go!

#7 John rombi

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Posted 16 February 2013 - 04:15 PM

Brett, By the time you source all the "bits n pieces" you would be better off buying the heater. I use the DG-1 with great success on my 12" Lightbridge.

#8 Brett Carlson

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Posted 16 February 2013 - 09:10 PM

The dew heater in pretty much complete. All i need to do is caulk it up a bit to seal it up. Cost about $50.00 total.

I might buy the heating elements themselves...especially the heater for the telrad as that is a very tight fit. I'm pretty sure that I can get the secondary heater and eyepiece heater working.






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