Vibroplex bob weight thread?

Discussion in 'Straight Keys - CW Enthusiasts' started by G0ILN, Jun 11, 2019.

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  1. W6MK

    W6MK Ham Member QRZ Page

    What, exactly, is the difference in terms of lateral forces at the pendulum pivot of a bug under these two cases:

    1. A weight added at the end of the unmodified pendulum which slows the dit rate a specific amount.

    2. A length extension to the pendulum which adds less weight to the pendulum but at a further point
    from the pivot than in case 1, but with the dit rate reduction the same as in case 1.

    Without doing the analysis, my guess is the smaller weight of the pendulum extension produces the same
    pivot lateral forces increase as the greater weight at the end of the unmodified pendulum. Thus wear and
    tear should be equal in both cases.
  2. WR2E

    WR2E Ham Member QRZ Page

    Could well be!

    The odd thing to me though is that even as you say, all things equal, one might expect the same 'sound' from either method.

    The two methods 'sound' different to me.

    It feels different sending also.

    Somebody good at physics might be able to explain why.

    I think there's more 'dwell time' when the change of direction occurs.
  3. W6MK

    W6MK Ham Member QRZ Page

    Bug "feel" is very sensitive to several adjustments. One would think that with a longer pendulum
    or an unmodified pendulum with more weight, the dynamics of the main lever would change.

    And thus the contact gap/lever stroke distance for each setup.

    When we change a bug's geometry and weight load, we are creating different instruments. It's the
    "apples to oranges" thing.

    The original issue was with wear at the pivots. I still don't think it will be demonstrable that a bug
    being slowed down with alternative methods will change the pivot wear in any significant way.

    A ham who made replacement parts for Vibroplex bugs for many years told me that there was no
    difference in "feel" or in wear between the standard bugs with metal pivots and the deluxe models
    with jeweled bearings. Maybe this suggests something significant.

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