Odd IC-7410 antenna tuner problem

Discussion in 'General Technical Questions and Answers' started by KP4SX, Feb 13, 2020.

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  1. KP4SX

    KP4SX Premium Subscriber QRZ Page

    Something has changed with my 80m tuning. Ant is Butternut HF6V and rig is an IC-7410.

    Of course the vertical has always had a rather sharp SWR curve and ran about 2.5:1 at 3573 kHz. The internal tuner in the Icom handled it just fine. Similar story down at 3.501. Antenna SWR curve is centered around 3.530 or 3.535. All that seems typical and worked out well for me.

    But now the tuner can't seem to do anything at all with 80m, even at the sweet spot of 3.530. It just goes searching around even with a dummy load.

    Of course the first thing I checked was the antenna. All seems ok, sweet spot and hi/lo swr points are pretty much the same as they have always been. Now I'm wondering if something has gone on the fritz with the internal tuner. I can get the SWR down well with an external tuner and my outboard SWR meter agrees with the Icom's SWR meter but if the auto-tuner is engaged it just goes nuts.

    I seems to recall something about the rig holding tuner settings in a memory but I cannot find any details on this. I wonder if a Factory Reset is needed to get a blank slate again? or if there is an actual failure in the tuner circuitry? Anyone else have any similar experience?
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I don't have a 7410 but note that the rig does have a separate CPU just for the tuner and does have an alignment/test instruction for the CTRL unit, where the circuitry is located that control the ATU.
    The "short plug" is a 1/8" mono plug shorted pin to sleeve and plugged into the REMOTE jack on the rear panel.

    If a general "reset" doesn't work, you might try what's shown above.
  3. KP4SX

    KP4SX Premium Subscriber QRZ Page

    Hmmm, interesting. It seems normal on all other bands, only 80 is screwing up. Where am I supposed to see * ***OK*** * ? Will it be on the main display somewhere?
  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Beats me. I'd assume on the panel display, but I've never had a 7410.

    Did you try a master reset already?
  5. KP4SX

    KP4SX Premium Subscriber QRZ Page

    Not yet. I'm a bit skittish about it all. I downloaded that service manual and its absolutely terrifying!
  6. KP4SX

    KP4SX Premium Subscriber QRZ Page

    I did the Master Reset yesterday to no avail other than deleting my preferences and settings.
    This morning I did the tuner reset procedure like Steve shows in Post #2. I didn't open it up and do the adjustment. By golly I think I have fixed it!!! When you power up with Menu and Filter depressed the display goes to a different screen. When you push STR (F-5) it steps through each ham band and recalibrates itself and its on that screen where you see the OK indication.
    Cool! Thanks, Steve.
  7. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    These rigs are so smart.

    When it flashed OK on the screen, it should also wink and show a thumbs up.:p

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