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Circuit diagram required

Discussion in 'Radio Circuits, Repair & Performance' started by SP7WT, Jun 15, 2021.

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  1. SP7WT

    SP7WT Ham Member QRZ Page

    I have a Collins made vacuum capacitor assembly which I would like to use for a remotely controlled ATU.
    Is someone able to provide its circuit diagram ?
    Tom, SP7WT DSCN9580[1].JPG
  2. G4COE

    G4COE Ham Member QRZ Page

    Hi Tom, is there any model or part numbers on that lable we can see?

  3. SP7WT

    SP7WT Ham Member QRZ Page

    Hello OM Dave and thank your for your interest. I am afraid, there is no Collins part number, only a sticker stating that some updates have been made according to service bulletins. I would like to preserve the original circuit but another option is to modify it.
    It has two limit switches, so it works in a similar way to an antenna rotator. Needless to say, an impressively made component.

    73! Tom, SP7WT
  4. SM0AOM

    SM0AOM Ham Member QRZ Page

    I wonder if this may be the series capacitor part of the 1950s Collins antenna tuner 180L-3 used with the AM 618S and the first incarnation of the SSB 618T.

    A similar unit, but with a larger capacitor also was used with the 18Z.

    It looks very similar to my unit which was used with the 618S on large air transport aircraft in the mid-1950s.


    KA9JLM likes this.
  5. SP7WT

    SP7WT Ham Member QRZ Page

    Your response is spot on, OM Karl-Arne. It is a correct diagram for my assembly.

    TNX, Tom, SP7WT

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