Homemade dew preventer for telrad and eyepieces

[Mr Flibble]

I've had one too many nights spoiled by dew clogging up my eyepieces and telrad. First I tried a dew preventer like this for my telrad but I found it not very successful, and nothing I tried worked when it came to the eyepieces. Dew has annoyingly cut short my last few sessions so out of desperation I've resorted to building a little heat supply for my telrad based on this thread provided by M110 (thanks :-)); and the info for the eyepiece heater I got from Sky and Telescope - they recommended a heat output of 1.5 watts for finder and eyepiece but I went for 2 watts to be on the safe side.

I use a rechargable 6 volt power supply which plugs into a dc socket on the telrad with velcro at various locations to keep the cable tidy (the reason the socket is positioned at the front of the telrad is because its the least obtrusive place, even if it does look a bit unsightly). A rocker switch is used to power on and off (next to the pulser control). Its wired to a resistor next to the glass of the telrad to provide heat and prevent dew. The cable then runs out of the telrad to my eyepiece heater which consists of a series of resistors which wrap the eyepiece and is held tight with a velcro strap. It easily adjust for various size eyepieces and the cable has plenty of length for ease of movement and velcro, again, keeps things tidy. When the eyepiece heater is not being used it just attaches to the side of the telrad with velcro and is unobtrusive.

Now I'm just hoping that next time I'm out on a session it works and that I'll be spending my time observing and not wiping and swearing :-)