Thursday, 27 October 2016 | David
I bought three of these strips about a year and a half ago: An 8, 4 and 2".
The 2" failed after 1 year of use looks like one of wires has disconnected because it's not properly seated inside the material so it was bound to fail through use bending occasionally.
The 4" has now failed and just heats up the wire instead of the dew strip so I assume it's shorting.
So with real use I can't recommend these they don't appear to be sturdy enough especially for such an expensive product. While they work hey work well but failing after such a short period of time is not really acceptable.
Sunday, 12 April 2015 | Phillip
Dew formation was the one thing guaranteed to spoil an otherwise good observing session, with frequent uses of a hair drier to get rid of it. Iím pleased to say that using Astrozap this winter means that Iíve not had any problems with dew formation at all.
The principle of this dew prevention method is very simple. A heating strap is wrapped around the tube at the point where the lens or corrector plate is held in place. The controller then heats the strap, and the conductive heat stops the glass from cooling down below the dew point. This prevents dew forming on the glass surface. The controller device regulates the amount of heat used to do this without warming the optics too much, which can cause its own problems. However, there is no immediate way of knowing what setting to use, or for how long, in order to get this balance. Having used this for a few months, it seems the unit needs to be turned full on for a short while to begin with, and then turned to a lower setting for the rest of the session. Colder and/or higher humidity requiring higher settings and duration. Itís a matter of trial and error, and gaining experience with it.
The heating strap is fastened tightly to the tube by a velcro pad, and the controller can be attached to the pier, tripod or mounting with another velcro pad. Care has to be taken to avoid the strap lead from wrapping around the mounting. I use my controller with an 8" strap which requires around 1.2A. The controller can handle up to 5A over 2 controllable channels with 2 sockets each, so other straps can be used at the same time.
My only gripe is the bright, wide angled, green power LED which, when the eyes have become dark adapted, is very irritating. A piece of red cellophane stuck over it has solved that problem. The two yellow LEDs which indicate the power going to the 2 channels are much dimmer and no problem at all.
Obviously it is yet another piece of kit to take outside when observing, but it is well worth it. In an observatory it is an essential item which can be permanently installed.