NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Bubble horizon
From: Robert Eno
Date: 2002 Dec 19, 00:45 -0500
From: Robert Eno
Date: 2002 Dec 19, 00:45 -0500
I find a microwave oven works very well for restoring desiccant crystals. ----- Original Message ----- From: Paul HiroseTo: Sent: Wednesday, December 18, 2002 4:20 PM Subject: Re: Bubble horizon > > The biggest drawback to the Kollsman is the reflective "pellicle" which is > > situated inside of the body of the unit which transmits the image of the > > celestial body to the eyepiece. Once it starts to absorb moisture it > > wrinkles and spoils the view. For this reason, the Kollsman is fitted with a > > removable cylinder which contains a desiccant to keep the pellicle dry and > > taut. Every once in a while, you must remove this cylinder, dry out the > > desiccant and replace it. Unfortunately for me, I left it for to long and > > the pellicle self-destructed. I have not made much of an effort to find a > > replacement so if you ever come across a supply of them, let me know. > > > > Thanks for the warning regarding the dessicant. My Kollsman arrived > this morning. Looks like it's in excellent condition. Paint is near > mint, image is sharp, bubble size adjustable over a wide range, > mechanical averager checks out fine. There are two dessicators. One is > a tiny capsule visible through the window at the top of the optical > tube. The other is in the sextant body. They're both turning pink, so > I guess they ought to be filled with fresh crystals. The quantity is > so small, it hardly seems worthwhile to bake the old dessicant in an > oven. I need to research where to buy the stuff, though. > > When I was in the service we ordered dessicant by the gallon can. It > was used to keep radar waveguides dry. New parts often arrived packed > with little pillow bags of dessicant as well. They were usually > discarded, but my boss saved them to keep humidity down in his gun > cabinet. >