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Yaesu FT-450 Tx Power when Ext Tuner Activated

Discussion in 'General Technical Questions and Answers' started by CS7BAC, Mar 25, 2021.

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  1. CS7BAC

    CS7BAC XML Subscriber QRZ Page

    Hello from Portugal!
    I have a FT-450 (initial verison, not AT or D) and i have a newbie question: as my radio doesn't have internal ATU, i got one from eBay (mAT-30) which is supposed to handle up to "120 watts SSB and CW, 30 watts max continuous duty keydown digital modes on HF".
    It was working perfectly fine for couple weeks, but yesterday when i pressed the "TUNE" button on FT-450 the magic smoke popped out of the ATU box. Checking inside it i have noticed that all the 100R and 110R resistors which handle the input RF power from radio before delivering it to the tuning circuit have been "fried".
    In contact with the supplier they stated that this is quite strange because the output power from the radio when we use the "TUNE" button is supposed to be no more than 10W, however i put the radio RF OUT to my Daiwa Wattmeter and measured nominal 100W out when i press the TUNE button.
    Supplier said this is quite strange and i may have some issue with my radio, what trully speaking i don't believe.
    As i don't have another radio to check this information, i wondr if some of you guys with experience on this subject could tell me more about it or maybe even someone with a FT-450 could confirm to me if the output power is really the nominal 100W power when pressing the TUNE button.
    For your record, i was using USB mode on 20m band.
    Thanks!
    73 de CS7BAC, Pedro Silva.
     
  2. G8FXC

    G8FXC XML Subscriber QRZ Page

    I don't have an FT-450 (do have an FT-991A) - but I would expect that the tune button would reduce the output power to something like 10W. I do have some vague memory from around the time that the 450 was released of hearing something similar to your experience, but I don't remember any details.

    For future reference - assuming that you either fix your mAT-30, or replace it - Yaesus have a very useful feature that largely removes the need to use the TUNE button. Somewhere down in the menus, you should find an entry which is referred to as something like "Auto CW". If you turn that on - and plug a morse key in - tapping the key will switch to CW briefly and send a carrier; releasing the key will put you back to the mode you were in. Add to that the fact that all reasonably modern Yaesus remember the power output setting by mode, and you have an easy way to tune up - just manually switch to CW and turn the power output down to ten or fifteen watts, then switch back to your mode of choice. From that point on, your morse key will effectively double up as a tune button.

    Martin (G8FXC)
     
  3. CS7BAC

    CS7BAC XML Subscriber QRZ Page

    Hello Martin!
    Yes, it is indeed a very good option. Thanks for sharing your experience!
    However now i got a little concerned if my radio has some defect because it is delivering its nominal set band power (which in my case is 100W for 20m USB) instead of this attenuated ~10W on TUNE event...
    Maybe someone else will see this thread and give some extra idea.
    Thanks and 73!
    CS7BAC
     
  4. G8FXC

    G8FXC XML Subscriber QRZ Page

    My recollection - which is very fuzzy - was that the issue was related to the use of the tune button. I seem to remember it being one of the reasons why I ended up adopting the Auto CW approach towards tuning - but I must stress that this was a long time ago and with an FT-2000, not an FT-450 (though they are close relatives).

    Martin (G8FXC)
     
  5. CS7BAC

    CS7BAC XML Subscriber QRZ Page

    Hey Martin, i replaced the resistors on the ATU and tried what you said but actually keying the CW in CW Auto mode with 10W set power will not activate the mAT-30, but only switch it to the memorized position of relays that was tuned before on that particular frequency. To enable the tuning process on the ATU i think it is only using the TUNE button, unless there is some other config that i am missing about the usage of external tuner. Any extra idea?
    TKS
     
  6. G8FXC

    G8FXC XML Subscriber QRZ Page

    Hmmm, I am surprised... I don't know that tuner, but I didn't think that the Yaesu tuner interface had that level of control. What do you have the tuner menu configuration item set to? I see from the manuals that the FT-450 has an unusual options as in "F TRANS"...

    Martin
     
  7. CS7BAC

    CS7BAC XML Subscriber QRZ Page

    Yeah, on TUNER setup menu we have ATAS/EXT ATU/INT ATU/INTRATU/F TRANS but as per my understanding there is no other possible option to activate a generic external ATU than EXT ATU, by a straight manual reading. Maybe for FT-450 this nice trick you told me won't work accordingly... Bad luck!
    Pedro.
     
  8. N2PQW

    N2PQW Ham Member QRZ Page

    Hello Pedro,
    When I owned an FT-450, I selected ATAS from the tuner menu. Then, when pushing the TUNE button, the radio would transmit the 10w carrier to engage the external tuner, and would continue to transmit until the SWR was adjusted to an acceptable level.
    I believe that you should try this and let us know if this meets your needs.

    Cheers,
    David / N2PQW
     
  9. CS7BAC

    CS7BAC XML Subscriber QRZ Page

    Hello David!
    No, it didnt work this way with ATAS. The radio just cannot control the ATU using this option. This seems to be specific for ATAS Yaesu antennas.
    The only option i can use that triggers the external ATU correctly is EXT ATU.
    Thanks anyway!
    73
     
  10. CS7BAC

    CS7BAC XML Subscriber QRZ Page

    Hi guys! Just to give a feedback myself on this thread and close the issue: it turned out that my FT-450 had a small problem on the control unit, which was causing the radio to Tx full power on tuning process. The problem was solved and now i get less than 10W while tuning, not reying anymore my ATU...
    Thanks!
    73
     
    N2PQW likes this.

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