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I wish to wire up a Silver Eagle D-104 Mic to use with my Maestro C

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KG5PTE
KG5PTE Member ✭✭
in Maestro

Hello, with the new Maestro C having a PTT 1/8 jack that requires Tip Sleeve (TS) and the HDST 1/8 jack that requires Tip Ring Ring Sleeve (TRRS) can I wire up a 1/8 jack for a old Silver Eagle D-104 mic and make it work ? This morning at our monthly radio club meeting I asked if it could be done. The question that I was told to ask the Flex experts is this. "Will the Flex 6400 and Flex Maestro C work with a high impedance mic" ?

Thank you.

Answers

  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin
    Options

    Typically, the Mic impedance is pretty low for these connections, but I am checking with our engineers. Usually under 100 ohms.

    For a high impedance Mic you'll like need to do some impedance matching which is pretty simple to do.

  • KG5PTE
    KG5PTE Member ✭✭
    Options

    Any word from the engineers about the D-104 Mic ?

  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin
    Options

    The Mic Impedance on the Maestro is about 32 ohms. This is done to limit RFI issues.

  • KD0RC
    KD0RC Member, Super Elmer Moderator
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    Hi James, I would just give it a try. The Flex has a built in 20 dB pre-amp if you need it. If that isn't enough, then I think that there are little amps available that fit in the D-104 base.

  • johnn1jm
    johnn1jm Member ✭✭✭
    Options

    In using a D-104 with a low impedance input, it is best to use something to match the impedance such as a transformer or an FET source follower circuit. You may be able to drive the radio without impedance matching ok but the frequency response will not be great.

    YMMV

  • KG5PTE
    KG5PTE Member ✭✭
    Options

    My Friend (NU5D) who is wiring up the D-104 mic for me told me this in response.

    Good
    info.  The cartridge itself is around 100 k ohm and needs maybe 1 Meg
    ohm in series to bring up the low end of voice (otherwise the D104 is
    very tinny)...   Trouble is 1 meg ohm in series will really really knock
    down the output of the cartridge (called a swamping resistor)...  That
    needs to be made up with a pre-amp stage.  The 20db in your radio might
    just be enough - easy to try.  I just need to wire the plug to the
    cable.  If there is not enough drive, then I might have to add a preamp -
    these are little ready made boards that boost the loudness.

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