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Slow Motion Drive repair or replacement

Discussion in '"Boat Anchor" & Classic Equipment' started by ZS1J, Mar 31, 2012.

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  1. ZS1J

    ZS1J Ham Member QRZ Page

    My only transceiver (after selling up all my ham gear some years ago when I threw my toys out the cot when restricted amateurs were given full HF privilege) is an Alda 103. I use this set just on 40 metres but the main tuning dial has some horrific backlash and tuning in a station is now fairly difficult to the point where I have resorted to getting close on the vfo and then fine tuning on the dial calibration capacitor.

    The backlash is in the slow motion drive, the type that has a few ball bearings inside, but the two halves are held together with bent over aluminium tabs which I know will break if I try and bend them straight to dismantle the drive.

    Has anyone successfully managed to repair one of these, or better still, know of a place where I can order a replacement drive.

    Thanks Roger ZS1J
  2. ZS1J

    ZS1J Ham Member QRZ Page

    I should have added that this drive has a two speed ability. At either end of the coarse rotation, moving the knob in the reverse direction brings in the extra slow motion section for about 10 kHz before the coarse movement is returned. This extra slow motion is in both directions for said 10 kHz but with the excessive backlash.

    Just hoping someone can offer some help. 73
  3. KE3WD

    KE3WD Ham Member QRZ Page

    That type of drive usually fails due to hardened lubncating grease.

    I would not try to disassemble it either, and you likely do not have to do that. Instead, spray it out with a quality degreaser spray, using care not to let the spray hit any other part of the radio. Then inject a light grease into the balls, races and such.

  4. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    I remember that rig but never owned one and don't recall the drive mechanism used.

    Sounds like a "planetary drive" mechanism, and 2-speed versions as you describe were pretty common. Does the drive mechanism mount to a panel or chassis with two bolts or screws and can it be decoupled from the VFO shaft by removing a coupling?

    If so, I'd remove it entirely from the rig and then do what KE3WD suggests. I've "repaired" these several times (if that's what you actually have) by using solvent in an ultrasonic cleaner (like what jewelers use to clean jewelry, we happen to have one at home which I mostly use to de-grease electronic parts) until it's absolutely clean, then just lube the bearings with an injector that looks a lot like a hypodermic needle. Works every time.
  5. W9GB

    W9GB Ham Member QRZ Page

    Last edited: Apr 1, 2012
  6. ZS1J

    ZS1J Ham Member QRZ Page

    Thanks for the information chaps. I will do both things. Dismantle and try and clean it out whilst at the same time place an order with the company in UK that was on the link you gave me for a brand new drive.

    Boy is ham radio a great hobby or what and rules.
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