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I may have messed up my tuner

Discussion in 'General Technical Questions and Answers' started by WY4K, Sep 12, 2018.

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  1. WY4K

    WY4K Ham Member QRZ Page

    I made a mistake and hooked the transmitter up to antenna port 2.

    I have a mfj 993b tuner. I ran the tuners check out and it comes back that the unit is in good working order. However, sometimes when the tuner is tuning to a different frequency, it will show a message to turn power off. After turning the power off several times the tuner will tune to the selected frequency. Sometimes after I transmit ssb for a few minutes the tuner will show the message to turn the power off. The tuner seems to continue to work fine once tuned even though it shows the message to turn the power off.

    Has anyone made this mistake or gotten this message on their tuner? If so was you able to make the repair or is this a repair that only mfj can make?
  2. K0OKS

    K0OKS Premium Subscriber QRZ Page

    Is it saying to turn the power off or decrease the power? Do you have an interface cable hooked up so it tunes with your rig, or are you just use the auto-tune? It really wants about 15-20W to tune, more is bad, less is bad. Ideally this is a pure carrier (CW tone) at 15W. Many modern rigs output this tone at this power level when you press the tune button on the rig. Some rigs do not have this.

    If you do have the interface cable then try it into a dummy load (output of the tuner to the dummy load rather than the antenna). If this works fine then I would try some mix 31 ferrite on the interface cable, which could be picking up RF from your antenna. What type of antenna, and how close is it to the tuner?
  3. WY4K

    WY4K Ham Member QRZ Page

    I am using the interface cable. I am using the tune button on the transmitter. The message is turn the power off. When this message appears there is a tone like a cw tone and this tone will not stop when tuning until the power is turned off on the tuner.

    The antenna is a dipole located about 70 feet from the tuner.

    I will try the beads on the interface cable.
  4. KA9JLM

    KA9JLM Ham Member QRZ Page

    How did you turn it off ? Did you remove power completely ?

    Good Luck.
  5. WY4K

    WY4K Ham Member QRZ Page

    I just use the power on off button on the tuner.
  6. W2WDX

    W2WDX Subscriber QRZ Page

    I don't use auto-tuners or buy MFJ. Doing both prevents that problem every time. I buy quality stuff and use my own brain; not depend on some co-processor to think for me. But hey, good luck with that TKO.
  7. WY4K

    WY4K Ham Member QRZ Page

    Now that I know how stupid that I have been, I will just slink away with my head held low.
  8. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    I have a remote MFJ tuner, it works just fine. No need to slink away!

    I think KA9JLM may have been suggesting to remove power completely for some time, not just use the power button. This will guarantee a processor reset in case the power button doesn't do it. Also, there may be a procedure in the manual for a full factory reset.
    WB7OXP likes this.
  9. KA9JLM

    KA9JLM Ham Member QRZ Page

    That was a hint worth trying after looking at the schematic.

    The power switch does not turn off everything.

  10. WY4K

    WY4K Ham Member QRZ Page

    Thanks guys for the tip to turn the power off for a long time. I have left the radio and the power to the antenna tuner off for over 2 weeks. This did not solve the problem.

    I have looked at the schematic of the tuner and I can't determine if 100 watts going into an antenna port would have damaged the components or not.

    Does mfj have a site that might be able to give me some answers or suggestions?

    I really need to do a better job or grounding my equipment. So if MFJ can't give me some tips, I will start trying to get a better ground for everything.

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