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    Re: Bubble horizon
    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 Hirose 
    Sent: Wednesday, December 18, 2002 4:20 PM
    Subject: Re: Bubble horizon
    > > The biggest drawback to the Kollsman is the reflective "pellicle" which
    > > 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
    > > 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
    > > the pellicle self-destructed. I have not made much of an effort to find
    > > 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.

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