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    Re: Instrument repair
    From: Robert Eno
    Date: 2002 Dec 19, 01:16 -0500

    Hello Ken,
    Couple of things: one comment, three questions:
    1. Regarding the fluid in the C.Plath bubble attachment, thank you for that
    information. I have been trying to find this out for years. I tried to get
    the answer from C.Plath in the early nineties, but came up with more
    questions than answers. I ended up removing all of the original fluid in
    mine and replaced it with xylene. Once I overcame the leakage problems
    inherent with xylene, I've never had a problem with the attachment. The
    bubble seems to work very well.
    2. Do you know who can fix the averager on a MK IXA?  I have one old one
    that was given to me but the averager is shot. I opened it up and quickly
    realized that the mechanism is beyond my understanding.
    3. It seems to me that you used to have the testing equipment for the MK IX
    A. Do you still have it? I may have asked you this before.
    4. Finally, on two of my MK IX-A's the fine setting knob is becoming very
    stiff; to the point where it is difficult to turn. I have some instructions
    from a fellow in Australia, but I am reluctant to tamper too much with them.
    Any thoughts?
    Robert Eno
    ----- Original Message -----
    From: Ken Gebhart 
    Sent: Wednesday, December 18, 2002 10:58 PM
    Subject: Re: Instrument repair
    This is predicated on the fluid in the chamber being
    > xylene, which it is in all aircraft sextants except the Kollsman
    > sextant which has a silicone fluid, as does the C. Plath marine bubble
    > We have not heard of a recommended size for these.
    > 7.  Mr. Eno is right again about the RAF MK IX A and B being the best
    > We have handled probably every aircraft sextant ever issued operationally,
    > they all have some inherent drawback - some design flaw (such as the
    opaque bubble
    > in the AN 5851-1), except the MK IX.  It is not very elegant looking, but
    > simplicity is very attractive.  As a result it is remarkable easy to work
    > Anyone can do it, save fixing an averager.  The B model is the same as an
    A model
    > but with an external averager conected by a shaft.  About 5 strokes with a
    > on this shaft will convert a B model into an A.  BTW, Celestaire has
    > manuals for sale for almost all aircraft sextants ever made.
    > Ken Gebhart

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