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HP 8640b

Discussion in 'Electronic Equipment' started by eric van slee, Oct 23, 2003.

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  1. Hello,
    I have a HP 8640B RF Generator with some broken nylon gears inside. This
    appears to be a frequent problem. Does anyone know where to obtain spare

    Best Regards
  2. KLØS

    KLØS Guest

    Take a look at Jose Gavila's web page describing a problem with his HP8640's
    gears....although he doesn't offer a solution for the broken gear he does
    describe a homebrew solution to fixing some of the fingers on the wafer. He
    may have some suggestions if you contact him.

    Dino KLØS/4
  3. Dan Rae

    Dan Rae Guest

    They're Delrin ,and yes it's very common with the older serials, along
    with the little switch fingers falling off the plates, never to be seen

    Let us know if you find an answer, I never did, mine's sitting in a heap
    in the garage :^(


    They can be fixed. I had 2 cracked gears. Both are now repaired.
    I'll post pictures when I can (or when I remember).

    1. Take photographs of the gear assembly before removal so you know
    how it goes back together. The meshing of the gears must correspond
    to a starting point, so also record the position of the front panel
    dials before disassembly. Be sure to record the position of the clear
    plastic switch armatures.

    2. Tear it apart and remove the cracked gears. The gear cracks
    because the delrin gear shrinks onto the brass center piece. If you
    just glue it together, the gap between the gear teeth on either side
    of the crack will be excessive.

    3. Remove the delrin gear from the brass center piece and file the
    center hole in the delrin gear to enlarge its diameter. Leave a
    little extra space around the brass center piece for the glue. Make
    sure that the gap can be closed. Leave the filed area slightly rough
    for good adhesion. You may also need to enlarge the hole around the
    set screw for clearance with a small round file.

    4. Glue the gear to the brass center piece with 24hr epoxy (not the 5
    minute type). Clamp the gear in a vice, glue clamp, or whatever,
    being very careful not to crush the gear teeth. Be sure the crack is
    closed, properly aligned, and that no glue slops between the teeth.
    Do it right the first time. Keep warm, and wait 24 hours for the mess
    to dry before even looking at the results.
  5. Thank you,
    This seems a good advice that I will try.
    And I am interested in the pictures.

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