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Thread: Homemade coils to use a MFJ analyzer as a dip meter

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  1. #1

    Question Homemade coils to use a MFJ analyzer as a dip meter

    Is anyone has the design of homemade coils to use a MFJ analyzer as a dip meter?

    I think that in Nov 1993 there was a QST article on this...

    I thank you in advanced,

    Luis, CT2FZI

  2. #2
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    All you need for frequencies of 1.8 to about 20 MHZ is a BNC connector and some 3/8 inch plastic tubing. Wind about 8 turns of #14 spaced one wire diameter and cover it with shrink tubing.

    I have the MFJ kit and have used it but the results are marginal in most cases. I prefer to use My Millen GDO which is far far more sensitive.
    I'm sorry you don't have the experience or understanding to realize that others possess a skill set that you seem to dismiss as fantastical.

  3. #3

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    Thanks!

    That is what I was looking for

    Luis, CT2FZI

    Quote Originally Posted by KA4DPO View Post
    All you need for frequencies of 1.8 to about 20 MHZ is a BNC connector and some 3/8 inch plastic tubing. Wind about 8 turns of #14 spaced one wire diameter and cover it with shrink tubing.

    I have the MFJ kit and have used it but the results are marginal in most cases. I prefer to use My Millen GDO which is far far more sensitive.

  4. #4

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    Quote Originally Posted by CT2FZI View Post
    Is anyone has the design of homemade coils to use a MFJ analyzer as a dip meter?

    I think that in Nov 1993 there was a QST article on this...

    I thank you in advanced,

    Luis, CT2FZI
    Another answer:

    > You can try simply winding a few turns of hookup wire on a convenient
    > tubular form, hooked up to an RCA or BNC or PL-259 glued to the end of
    > the form, and see if you can get an adequate dipping for your
    > purposes.
    > The higher-frequency MFJ coil seems to be about 4 or 5 turns of wire -
    > length is about 1/2" and diameter is somewhere around 3/8". The
    > lower-frequency coil is somewhere around 12-14 turns of wire,
    > close-wound on a 1/2"-diameter plastic form.


    Source: http://newsgroups.derkeiler.com/Arch.../msg00804.html

  5. #5
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    Just remember that no matter how you fabricate it a proper Grid Dip Oscillator will work far better in every application.
    I'm sorry you don't have the experience or understanding to realize that others possess a skill set that you seem to dismiss as fantastical.

  6. #6

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    Quote Originally Posted by KA4DPO View Post
    Just remember that no matter how you fabricate it a proper Grid Dip Oscillator will work far better in every application.
    Thanks! That is very true.

    I just want to take the full advantage of my MFJ analyzer, not just reading SWR...

    I would like to know what it can or can't do, and learn from it

    Like complex calculations... It will be fun!

    Luis, CT2FZI

  7. #7

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    I just had another brainstorm idea of how to use the MFJ-259B to find the resonant frequency of a trap. Cut a 1/4WL stub to exactly the trap target frequency. The MFJ-259B manual tells how to do that.

    Connect the trap to the open end of the stub and tune the MFJ-259B for the minimum impedance. When the minimum purely resistive impedance frequency is equal to the target frequency for the trap, the trap is tuned to the target frequency.

    Of course, this requires a 1/4WL stub per trap.
    73, Cecil, www.w5dxp.com
    Can CO2 emissions save us from the coming ice age?

  8. #8

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    Quote Originally Posted by W5DXP View Post
    I just had another brainstorm idea of how to use the MFJ-259B to find the resonant frequency of a trap. Cut a 1/4WL stub to exactly the trap target frequency. The MFJ-259B manual tells how to do that.

    Connect the trap to the open end of the stub and tune the MFJ-259B for the minimum impedance. When the minimum purely resistive impedance frequency is equal to the target frequency for the trap, the trap is tuned to the target frequency.

    Of course, this requires a 1/4WL stub per trap.
    Thanks! I will see what the manual sais about it. Its a very good idea too.

    Luis, CT2FZI

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