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Dosy TC-3001-P meter SWR will not adjust to Set Line...?

Discussion in 'Forum Help & Info' started by jimbowilly, Apr 4, 2020.

  1. jimbowilly

    jimbowilly Member

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    Hi,
    My Dosy TC-3001-P meter will not adjust to the Set Line for channel 40. Works fine for channel 1.
    Please help
    Thanks,
    jimbowilly


     

  2. jimbowilly

    jimbowilly Member

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    Ok. I tested with a 50 Ohm dummy load and dead key swr's are 1 for channels 1 and 40 on my Dosy TC3001P. I checked both ends of my 50 ft - RG8X coax with the other end attached to my 50 Ohm dummy load. The Ohms were slightly over 51 Ohms(+ a few thousandths). So I disassembled my antenna and inspected and cleaned all components. I found my ground plane radial end connectors are corroded where they attach to the radial wire ends( I have issues with metals corroding around my house due to salt spray emanating from near by state road). My antenna set up is a 102" stainless steel whip elevated to 10ft, with two 10 ga. coated copper wire radials cut to 102", each set at about 37°. This antenna set up originally tested 7 yrs ago at just over 51 Ohms. And I was able to tx and dx during skip to California, Main, Virgin Island, Puerto Rico... And normally I can clearly converse with locals up to 40 miles away. Even with using a 50 Ohm dummy load, attempting to adjust the Dosy TP3001P is like trying to catch a kids balloon on a gusty/windy day. I intend to contact Dosy for re-calibration of this meter. I will be replacing the ground plane radials and retesting tomorrow. I will post the results of the new ground plane wires/connectors once they are installed.
    Thank you,
    jimbowilly
     
  3. jimbowilly

    jimbowilly Member

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    Tough trying to figure out set up issues when no one replies while talking on my radio or posting threads. Reviewing my original set up notes and just working to restore my set up has refreshed my memory enough to get me through many of the issues I'm currently attempting to overcome.
     
  4. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

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    I think everyone is still asleep.
     
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  5. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

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    What does that meter do with a short piece of coax to the dummy load?
     
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  6. nomadradio

    nomadradio Analog Retentive

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    This section was meant to help with issues using the forum software.

    Putting it in an "antenna" section probably would have gotten you more eyeballs on the post.

    Does the meter's SWR scale calibrate normally with the dummy load in line with it?

    The radio's carrier wattage is an issue, as well. If it's turned down too low, that could create the issue you had.

    73
     
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  7. jimbowilly

    jimbowilly Member

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    The meter does work with a short coax and dummy load. But it's still really difficult to adjust the needle exactly over the Set Line.
     
  8. jimbowilly

    jimbowilly Member

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    Yeah. I couldn't sleep until I figured out this issue with my set up.
     
  9. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

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    Not to sound dumb, but you did do some work to the antenna...

    Was the coax ever replaced?

    I've seen coax shield "wickup" water and turn black from the copper corroding out - which usually equates to ruined coax that has no business to be able to pipe RF anywhere - it just won't make it across to the antenna it's so lossy...

    And since were not sure of the radio - just wondering if a tune up done to it, may have affected the 52MHz trap filter in the back by the network. Everything ok in the back of the Radio?

    Just surprised the Dosy acted up on you this way...
     
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  10. jimbowilly

    jimbowilly Member

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    This a custom cb radio from Custom CB Radios. And he did tell me he set this radio up with a low carrier.
     
  11. wavrider

    wavrider W9WDX Amateur Radio Club Member

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    try a different radio see what it does
     
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  12. jimbowilly

    jimbowilly Member

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    Yup. I tried 2 different radios same result. When using a dummy load, both radios checked out just fine.
    So. I disassembled/cleaned antenna components. Checked coax, antenna, antenna mount for continuity. Installed new antenna radials. I am able to check swr with a Astatic PDC7 swr meter but the Dosy TC3001P still will not adjust to the set line.
     
  13. wavrider

    wavrider W9WDX Amateur Radio Club Member

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    two radios, two meters,
    one meter works fine PDC7????
    Sounds like it maybe some CMC on line doubtful though at low level of wattage.
    Looks like in accurate meter on the dosy, you have basically eliminated about everything there is to check.
     
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  14. wavrider

    wavrider W9WDX Amateur Radio Club Member

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    jimbowilly likes this.

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