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MEFFA Tuning Procedure ?

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N3PS
N3PS Member ✭✭

After a few weeks of running my Power Genius, I’ve just realized that some of the odd behavior on digital (occasional power level jumpy and challenging to adjust during xmit) is due to MEFFA being enabled and not being properly “tuned”.

Are you PGXL ops executing the “tune” once and done, every ops session, every band, every frequency change, every x minutes ?

I currently have MEFFA turned off. Power setting is now stable, but amp now runs much hotter and fans louder . . . Would like to go back to MEFFA.

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Answers

  • Jay
    Jay Member
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    I use MEFFA all the time on CW and FT8. However, when going from AB mode to AAB like on SSB/phone modes, this requires careful attention to the drive level on phone. It may take a few cycles for everything to catch up. Much easier going from SSB which takes less drive in the AAB mode to CW/FT8 which takes more drive in the AB mode.

    I have a full time wattmeter that I watch during TX, but rarely look at it once I know things are good to go and settled in.

    When running legal limit on CW/FT8 you really need to lower the drive on SSB just a tad. Otherwise you will be grossly overdriven on SSB. At least that is my experience.

    In summary, when in MEFFA AB modes like CW and FT8 need more drive because of higher bias. SSB in the AAB mode needs less.

    I just made a real world test on 15m. While running 30 on the RF power slider, I can make legal limit on SSB while in AAB. Going to CW while the MEFFA is in AB mode, the power drops about half. You would need to sneak up on drive power if you wanted to run legal limit on CW. I never worry about power level, 800 watts is plenty in the AB modes like CW and FT8.

    You are very correct PGXL runs cooler while using MEFFA. I love the Utility program where I can also adjust the fan speed. Even in a small rack cabinet the fans are loud, but running FT8 it never gets warm while using MEFFA. Good luck and 73 de w5jay/jay..

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