Who needs an audio interface?

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  • Who needs an audio interface?

    Posted by wa3ltj on 2024-02-05 at 00:12

    I like to operate POTA and sometimes use an FT-891 mobile rig. The FT-891 has a USB CAT control. I use a cable from the PC to the rig. However, the rig does not have a built-in audio card interface. For modes like FT8, the manual says you can connect the audio signals in the rear of the radio directly to a sound card. I use an audio USB dongle connected this way. Why bother with an audio interface? What isolation do I need if the rig runs from a battery, the laptop runs from its own battery, and the antenna is a dipole on a tall pole? Outside of isolation, an interface (e.g. Signal Link) often has gain controls. However, the FT-891 can adjust the transmit and receive audio gains on the rear connector. I think the impedances are reasonably well matched with this setup. What am I missing?

    Jim replied 3 months, 2 weeks ago 2 Members · 3 Replies
  • 3 Replies
  • Jim

    Group organizer
    2024-02-05 at 01:35
    117
    25W posting rank

    Hey Andy.

    I can only speak to the isolation issue. I would think it’s a non-issue in that you are not connected to AC so no common ground. I mean, maximum isolation is always desirable, but in this case, I think, irrelevant. you should be fine.

    Now onto the ‘what am I missing?’ question. What are you referring to exactly, the isolation or the gain?

    • wa3ltj

      Group member
      2024-02-06 at 03:25
      11
      5W posting rank

      Is there any else to consider? That’s all.

      • Jim

        Group organizer
        2024-02-06 at 10:03
        117
        25W posting rank

        Funny how a phrase can mean two things. “Am I missing something” can, indeed, make one think of revising what was proposed, or if one has actually missed something. I guess I took the wrong fork in the road… 😅

        Nope, did not miss anything, other than when I first got my 891, I bought a Tektronix with it. I used it a couple of times but then, as we know, my HF from home became an issue. I am currently building back my go-kit and I will be trying to connect the Tektronix back to the 891. When I do, I’ll revert. This said, I really like the idea of an dongle. Did not even realize one could use one. Plan on looking into it.

        • This reply was modified 3 months, 2 weeks ago by  Jim.

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