Kenwood tl922

Discussion in 'Amateur Radio Amplifiers' started by M1CZZ, Mar 10, 2021.

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  1. M1CZZ

    M1CZZ Ham Member QRZ Page

    Hi the tl922 is the first amp I've own and it a bloody belter.
    My question is when tuning on 40 the plate is bang on the 40m
    section
    But when I'm peaking the load it stops at zero and won't let me carry on peaking the load
    Doe this sound right?
    as I say I'm new to amplifiers so still learning?
    Any advice will be welcomed
    I Just hope I've explained it right
     
  2. W1QJ

    W1QJ Ham Member QRZ Page

    The load will stay on zero on 160-40 meters until enough drive is given to lift the load off zero. Eventually it will lift off zero at around 400-500 watts output. As long as you drive it enough and the load lifts off zero you are fine. This is normal
     
    WQ4G likes this.
  3. WQ4G

    WQ4G Ham Member QRZ Page

    Same thing W1QJ said, but in a different way.... You're not driving it hard enough.

    WQ4G
     
  4. G3YRO

    G3YRO Ham Member QRZ Page

    Yes the Pi-Tank is really designed to Load the Linear Amplifier correctly at full power . . . which for the TL-922 is around 1200 watts output !

    If you are under-driving it (to get less output) the Load Control may well stay on 0 for max power output.

    The above applies into a Dummy Load, or an antenna that is a perfect 50 ohm match.

    However, in practice, the position of the Load control will also depend on the impedance of your antenna on the frequency you are using. You can sometimes get full power with the load control on zero . . . at the other end of the band it may be nearer 10 !

    (this applies to ANY Rig or Amp with a Pi-Tank)

    Roger G3YRO
     
    WQ4G and W1TRY like this.
  5. KB7VO

    KB7VO Ham Member QRZ Page

    Does under-driving result in any damage to the tubes or signal distortion, or just reduced output?
     
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    If you under-drive the amp intentionally by restricting drive power (lower-powered exciter, or one that can be "turned down" effectively and creates no "overshoot" at all), and tune the amp at that reduced power level, all should be fine and certainly won't damage the tubes or create distortion. The amp will just "LOAD" differently, with more loading capacitance required -- as discussed in the original post here.

    The issue is that with modulation (other than FM or true FSK RTTY), your "tune point" drive level might exceed the carrier level where you tuned the amp. And if so, that can create not only distortion but amplifier damage. This is why on SSB it's usually best to "tune up" using the most power your transmitter can provide and leave the amp tuning set that way even if you under-drive the amp after that. The occasional "peak" can sometimes reach the "full power" the transmitter can provide and if (and when) that occurs, the amplifier will handle it fine.
     
    AB0R likes this.

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