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Dosy TC-4002PSW Schematic/help needed

Discussion in 'General CB Services Discussion' started by dss56, Jan 11, 2019.

  1. dss56

    dss56 Active Member

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    I have a used
    Dosy TC-4002PSW
    Would anyone out there have a schematic/ info on calibrating this meter. I think the watts are off a bit and would like to get it calibrated or adjusted to what my other meters say for watts from the same radio when keyed up using a dummy load.



    thanks IMG_3168.jpg
     
    #1 dss56, Jan 11, 2019
    Last edited: Jan 11, 2019

  2. nomadradio

    nomadradio Analog Retentive

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    That meter has been made with more than one circuit board in it. The trimpots that serve to set each scale's calibration are marked clearly in some versions.

    Not so clearly in other versions.

    We use Bird meters that have had the elements checked for accuracy. The meter being calibrated goes in line with the dummy load, and the trimpots set to match the Bird's reading.

    If the trimpots are labeled "20w", "200w" etc, it's not a big deal.

    And if they're labeled "R4", "R5" and such you'll have to trace each wire from the range selector to the trimpots to identify what each one does.

    Here is the only manual I have for those. Pretty sure the circuit board in this one is bolted to two screws against the back panel, with the main wire from the "input" coax socket passing through the center of a doughnut-shaped toroid coil on that pc board.

    Don't ever remember seeing a diagram for any other version.

    We learned the hard way to make sure that the coax sockets are properly grounded to each other. Some versions simply rivet the coax sockets to the painted rear panel. Doesn't penetrate the paint to the metal back panel. I have some pics of what we do to bond the ground side of the coax sockets to each other and to the pc board. I'll upload them to post here when I get the chance.

    73
     

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    #2 nomadradio, Jan 11, 2019
    Last edited: Jan 11, 2019
  3. dss56

    dss56 Active Member

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    Thanks for the info I will open it up tomorrow and see if I can decipher the power meter section. much appreciated
     
  4. nomadradio

    nomadradio Analog Retentive

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    Oh, one more detail.

    The meter may say "4000" Watts, but the antenna switch is good for about one thousand.

    Don't push it harder than that, even if the coax-socket grounds are good.

    73
     
  5. dss56

    dss56 Active Member

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    Thanks but will never get that close to 1k watts mostly run stock and do repairs on radios mostly very little amp work so think im safe watt wise.
     
  6. SIX-SHOOTER

    SIX-SHOOTER Well-Known Member

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    I once owned one of those & had it calibrated.It was a Bad Joke & the readings always changed from day to day & usually every day.It was far from Accurate but I learned that it did not have a PEP reading circuit in it so it is impossible for it to read PEP.I replaced it with an Autek WM-1 & I could not be happier.If I get these meters in stuff that I buy I now use them for targets at the gun range since they are perfect for that & they catch those bullets just fine & don't waste my time or energy.Don't expect accuracy but they do just fine for an SWR meter but are expensive just for that purpose.

    SIX-SHOOTER
     
  7. Tallman

    Tallman W9WDX Amateur Radio Member, KW4YJ EXTRA class

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    Here.
     

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